Tachometer Needle Jumping

NH 750 TACHOMETER CIRCUITRY. in my case my engine is running fine. I have replaced my tach filter before on my 86GT from Rodney when my tach died. What could cause the speedometer & Rpm needles to vibrate then drop to zero and the emergency brake light to come on then go back to normal? While driving the car the speedometer and RPM's will fluctuate rapidly then drop to zero, the emergency brake light comes on then goes off and both needles return to normal. I installed a 10K 1/2 Watt resistor in the wire leading to the tach. Needle keeps bouncing around and not registering correctly. its the bouncing you get when an engine sputters if you know what I mean. I haven't taken it apart because I would like to send it to a forum member here who can fix it & possibly service the inside mech. Cleaning the tach wiring connections (all of them) is the real fix unless there's a problem with your tach or with the wiring running to the tach. We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon. 9L V6 Ford Ranger (Mazda engine). The needle does a lot of jumping around. Tach needle does not move: The problem can be that the 12Volt or ground connections are missing to the tach. Here is the trick to avoid binding the gears too tight: You will notice that you can take the end of the tach gear drive pin and push it in and out. it jump ALL the time, even if the car is not running what can cause this??? o. The speedometer has similar symptoms: The needle fluctuates, sticks in one position, will not return to zero, will not register past a certain speed, reads slow or fast, the odometer does not register or it also just does not work. The symptoms of tachometer problems are: a sticking needle, the tach will not register above a certain rpm, sometimes the tach works correctly and sometimes it doesn't, the needle does not return to zero when the ignition is turned on, the needle jumps radically or fluctuates, or the tach just does not work at all. Wired the adapter to the 2 neg post of coils ran hot to positive of 1 coil. The gentlemen I spoke to offered this as a slim chance to correct your issue. New spark plugs. Does the tachometer needle on your 1968-’74 bounce and not give a steady reading? Does your tachometer just not function? The tachometers on these Corvettes are cable driven from the distributor. Cut Your Own Hair; Buzzcut styles; Best Hair Clippers; Dyeing hair; Hair care. any ideas/suggestions?. Here's what I got: Flamethrower coil Pertronix ignitor Otherwise, stock Idle is a bit rough as wellwas that way with the Stromberg, and is still that way with the single Weber 40DCOE. When I decelerate, the tachometer needle goes crazy, jumping all over the place. Instrument Panel problems of the 2005 Chevrolet Silverado 21 problems related to instrument panel have been reported for the 2005 Chevrolet Silverado. Eckler's has tachometer cables whether you need and upper, lower, with or without automatic if you have cruise control or want to replace a full set. After 900 miles the fix is still good, no jumpy tach needle. When the tachometer is not working, while the hour meter shows hours the hours do not increase. No problems. it happened while I was coming to a stop but still at 5000 rpm. This Chevrolet reproduction tachometer kit has been manufactured to original factory specifications using today's modern manufacturing techniques. i hope you dont get the same problems i have had where on my 97 my speedo would jump from whatever my speed to was 99mph then drop to 0 then after awhile it would go back to normal i replaced my VSS and no go i couldnt even get the new sensor in!! i had to force the thing in and still didnt work and yes i went to other parts stores and bought about 4 different VSS sensors and notta thing they. When the SofC reached 80% I noticed the voltmeter needle pulsing and the i number was jumping from 30 to 40 but the tach was steady. Anyone performing their own automobile tune-ups knows how important it is to know your engines speed. Ecklers Corvette parts carries replacement and reproduction speedos, tachs, odometers, pointers, needles, lenses and bezels to make replacement in your Corvette much easier. Its infrared optics are fairly tolerant of dirt, but if it gets very dirty it loses sensitivity and high response speed. it has the words "A. The cable can spin but still be causing the problem. We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon. The motor was used throughout General Motor’s entire production line from 2003 to 2007. Had troubles locating the end of the cable opposite the tach, but with help from this board was able to find it. Sometimes if it jumps and changes engine sound,the throttle position sensor needs changing. Thanks for any insight. This repeats regularly. It also appears the tach is not accurate over 3000 rpm's. One member has posted a graph recording the startup of the Traverse. Vacuum would have no theoretical effect on Tachometer operation since the tach is electronic and simply reads the rhythm of the coil signals. I’m joining in the swap (details over at Amy Made That but hurry – it closes shortly). However, there is an issue with the tachometer and speedometer. Even when I turn the ignition off and on the tach needle stubbornly stays put at 400 rpm, doesn't even quiver. NOTE: Be sure the 0-ring is in place. As far as electronics go, what would make the tach needle jump so much? It's just so weird. The engine RPM is running fine, however i notice that the tach is inacurte, the needle kind of floats up higher than the motor RPM is acturally running. Such a device incorporating an odometer. It is electric start. NH 750 TACHOMETER CIRCUITRY. I have noticed a strange problem in my car – Swift Zxi 2006 model. I assumed that a wire got loose as I was driving the rig down our somewhat rough roads on the way to the ramp. I have a 86 R80 with 86K on it; the tach was service last year and is in good working order. The tachometer sensor may fail; if the tachometer needle jumps around and the transmission has harsh shifts or does not upshift, this sensor should be checked. - Interestingly, the tach actually works on 6V internally. To use the Tach, turn it on and let it sit for one minute to allow for temperature stabilization. It seemed to be running ok, but I did notice a little puffing, no black smoke, out the tail pipe and the odor of not completely burned fuel. At first, the needle on the speedometer would jump up and drop back down around 2 to 5 mph - but the vehicle was not surging like the speedometer said it was. Re: Tachometer Needle Jumps Super simple change, two yellow wires on top(stator leads) a gray wire (tachometer lead) and a red wire (charging lead) Two mounting screws attach it to the mounting plate on the side of the outboard. this problem is not very important because my engine is running fine but its really annoying. its the bouncing you get when an engine sputters if you know what I mean. When under way the needle will stabilize at a normal reading of 3,000 to 3,500 then spike repeatedly to around 5,000. Repair and Diagnosis of Problems with Your Imperial's Gauges if a car has even been jump started with a 12 volt battery (I know, it really makes the starter spin. probably somewhere near the tranny. My other cars dont do this. it never did this before, it is a 1996 Monte Carlo. is to tap on the dash while underway and the needle(s) jump into place. With the tachometer wiring diagram in front of you, check the underlying connections. The tiny tach is also sensitive to the distance from the plug and the type of plug so you can get a lower reading if you are too far away. My boat tachometer seems to be bouncing and not showing accurate RMP. make sure the dizzy and all its workings are tight. I tried it with the tach adapter and that didnt work. For those with a technical bent, this includes the GMT800, K20, GM360, and GMX380. Re: bouncing tach needle Check the ground at the Tachometer/Gauge cluster, or (better yet) run a temporary gnd wire from Tach to Battery Negative. Other than the needle sitting at 1000-RPM when the motor is OFF, it has worked fairly well. I managed to get the speedometer needle to stop jumping around, but now the needle does not register any speed at all. If the tach reads Zero, the problem is in the distributor or the wire coming from the distributor. This transmits a series of on/off pulses to the meter that are counted and displayed as speed on the tachometer. The jumping is a rapid movement of the tach accompanied by loss of power. Tuft & Needle was founded in 2012 by two software engineers from Silicon Valley who were fed up with the lack of transparency and fairness in the mattress in. Is this a bad Tach or is there a ground wire that could be causing this. Sections of this page. tachometer jumps almost to red zone, please help E46 (1999 - 2006). You may have a worn cable or worn Tach socket. Patented Raised AXYS® RMK® Chassis. If the needle does not move, remove the same dark green wire from back of the gauge and connect a jumper from the terminal on the back of the gauge to a good ground. anyway i had to jump it off. Until it tach needle starts to bounce and the idle goes below 1 rpm and the needle just goes lower like to 500 and when it does that the car shakes like it wants to die, then i can see the needle going up a little bit then back down just 1/2 a inch maybe. Jumpy speedo and tach. It hovers around slightly above 1k. That (bad) tach needle behavior could be caused by either a mechanical or electrical fault inside the tachometer. I connected the tachs using all new wire, didn't solve the problem. Any suggestions would be appreciated. Now it seems to be doing it as I shift gears. I am still having issues with my tach needle jumping uncontrollably. This Chevrolet reproduction tachometer kit has been manufactured to original factory specifications using today's modern manufacturing techniques. The latest Tweets from tachometer (@tachometers): "Discount Auto Meter Pro-Comp Analog Gauges Gauge, Pro-Comp, Brake Pressure, 0-2,000 psi, 2 5/ 8 in. The last time I drove my 85 GT I started getting a jumpy tach needle so I probably need another tach filter I believe. I have an 04 rev. Hi all, I couldn't find documentation on this, and before tearing my instrument cluster out, I was wondering if anyone's dealt with this already. After about 20 minute drive and pushy the tach to 5,500 rpm, the tach needle started its dance againjumping up to 6,000 RPM and then going deadthen to an accurate reading. If the "RPM gauge"-actually the tachometer-is jumping all over the place, that could indicate a problem with the engine or with the transmission. I am still having issues with my tach needle jumping uncontrollably. I finely got around to installing a tach and chose one that displays 2000 rpm at center. The problem is the needle jitters. With the tachometer wiring diagram in front of you, check the underlying connections. Which wire for Tach????? Civic/Del Sol. Any suggestions would be appreciated. When I tried to start it all it did was make a noise like when the battery does not quite have enough volts to turn the starter. probably somewhere near the tranny. It was burnt in half right behind the boot that pops on the distributor. The tach I took apart (from an 85GT BTW) used a proprietary GM part (Part #2505 4339) to drive the air core meter from the ignition pulses. 1955-72 SPEEDOMETER REPAIR Parts Needed: 37-32 Odometer Decals 1955 37-33 Odometer Decals 1956-72 06-74 Instrument Cluster Decal Set 1957 06-77 1957 Speedometer Needle To order parts call 1-800-456-1957 or visit ClassicChevy. Tach needle bounces around a lot in certain gears, like in the lower gears especially. My port tach has been fluctuating al over the place especially while at idle speed. '80-91 speedos are held in by 2 screws; '92-97 PSOMs are held captive by the surrounding gauge faces. You engine might have a vacuum leak , a misfire , injector somewhat out of tunecan be many things. The cable, like a speedometer cable, will wear and cause the needle to not hold steady because the cable ends are worn. International Tractor Parts 806 - Gauges. com FREE DELIVERY possible on eligible purchases. At idle, in gear, I do not see any movement regardless. Also, the gauge may need to be replaced. Connect the remaining wire (usually green) from the tach to the wiring for the engine per your boat's wiring scheme. Example: When I punch it and it shifts. Summit 800. Remove the tach from the dash and apply 12 volts and ground, tach needle should go to zero if working. I haven't taken it apart because I would like to send it to a forum member here who can fix it & possibly service the inside mech. make sure the dizzy and all its workings are tight. Thank you, Zach. It is like it lost it's starting point. The AFC wasn't registering RPM's becuase of a loose/bad connection at the ECU. I mean its bouncing a couple thousand rpm up and down. The tachometer, lites, hand warmers, all seem to be working. Are you an expert in this area? Share your knowledge and earn expert points by giving answers or rating people's questions and answers! This section of FAQS. What is the solution?Do I have to - Ford 1992 Explorer question. Asked the service dealer, they say it normal, anyone experience this. Now the needle jumps around most of the time, at idle or while riding. If the "RPM gauge"-actually the tachometer-is jumping all over the place, that could indicate a problem with the engine or with the transmission. Originally developed for steam locomotives, they are now used in the aircraft and automotive industry. The input shaft is polished steel running in pot metal with very. Quick question, sometimes my tachometer needle goes crazy. A - tach needle jumps the same with the engine running or not running. So I decided to get a 2 5/8" Auto Meter tach from their Pro Cycle series (model 19324). 2017 RTS 2WD. This is first a lubrication issue. I have a rotor RPM gauge that shows max rpm on start up, flicks all over the place erratically, jumps when I use the trim button, and sometimes settles in flight (just to give me some hope). It's OEM but was installed by the bike's prior owner. Here is the trick to avoid binding the gears too tight: You will notice that you can take the end of the tach gear drive pin and push it in and out. I installed the tach and fired up the bike. Tach started to jump with no sign of misfire then the mis started to show itself. well being as it was beautiful outside and i just finished my exams today i took the bike out for a ride. When new and clean the speedometer (and tachometer) likely had no lubricant applied anywhere. Not sure if this is any help, but I've got the same issue. You can even have them set it to your current time for a fee. Shop online for original OEM & replacement parts. I had a bad rectifier on my old 1976 Merc 50-HP, but it had failed in such a way that the tachometer kept working just fine. Sure enough the momment I hit 4000rpm in 3rd gear and on, the tach needle starts jumping up 500-800rpm and then comming back down to actual RPM. I have noticed a strange problem in my car – Swift Zxi 2006 model. While idling the tach shows 2-300RPM some times. Maybe it's the connection from the spinning tach cable to the sensor. I have a 92 Mustang GT 5. I will try to see if it is the cluster problem, thanks for that suggestion. The tachometer part number is stamped on the housing. Tranny was rebuilt and everything was fine for about 2,000 miles. The speedo cable for those old cars is like a spring. Since you have posted about the tach needle, I have paid attention to mine. I doubt it's the coil, either. So it is a Baron 3" bullet tach mounted on the bars. I am driveing normal down the road and the tach needle will suddenly spike or bounce around for a second then seddle back down where it belongs. 2005 F-Series Speedometer Needle Bounce, Cruise Control Drop Out, DTC P0500, and/or Uncommanded Wiper Activation: If any of the above conditions are present, inspect the wiring harness running behind the coolant bottle to the wiper motor for chafing on a brake line clip and shorting to ground. Becuase it just couldnt follow the AC from Zero to 110 and back at the speed the AC was cycling. Now I've acquired and installed a nifty little 2" VDO tach since I have an extra hole for one under the dash. The tachometer is a. O it is really annoying. 5k) the needle sometimes jumps so I added a small 1000uF cap between the 12v line and ground supplying power to the Tachometer and that cleanup the noise on the 12v line. since h&h auto is authorized ford/mustang service, we can repair these tach's quickly and at an affordable price. so it'll be "good to go" for a few years. 1955-72 SPEEDOMETER REPAIR Parts Needed: 37-32 Odometer Decals 1955 37-33 Odometer Decals 1956-72 06-74 Instrument Cluster Decal Set 1957 06-77 1957 Speedometer Needle To order parts call 1-800-456-1957 or visit ClassicChevy. The AFC wasn't registering RPM's becuase of a loose/bad connection at the ECU. After 900 miles the fix is still good, no jumpy tach needle. is that what you are seeing. The reason I think this is the case, is because my '65 has the 7,000 rpm tach, but there's no entry on the [original] window sticker charging for a tach. It should be just over the graduation mark below the "1". This was more sporadic, but now it's doing at almost every time. Tachometer bouncing - Pelican Parts Forums. Sometimes it reads normal but mostly wants to peg the needle. Just to make sure everyone does understand because sometimes I dont explain things well enough, Before any wiring is connected and tach was in box, needle was at 2k. The fluctuating tach on warm up is normal. so after the S-chassis car show and meet in anaheim couple days ago, while I was driving home I notice that my rpm needle is jumping up and down. Is this a bad gauge?. WD40 or a anon residue solvent, wash down the inside, make sure no muck, no other greases, no nothing. when i turn on either turn signal, my tach jumps and all the lights blink a little even with higher rpms. They tend to calibrate well at low and high RPMs, but they tend to read a couple of hundred RPM high when the needle is nearer to vertical. The more frequent the pulses, the higher the duty cycle of the one-shot output, the higher the reading on the ammeter. The car runs good,idles good but the tachometer is very jumpy. RESTORATION. My tach still jumps a lot though and the steady speedo makes it appear even more erratic in comparison. Which wire for Tach????? Civic/Del Sol. It dosent matter the weather conditions or anything. It doesn't have a light, but I may come up with a micro-glo coil that can be rigged. Frequency based The tachometer calculates speed by measuring the frequency of pulses More accurate for high speed measurement Time to take a reading is independent of speed of rotation. I have a Volvo Penta branded Tachometer, made by VDO Technik AG Switzerland. This is a clear dip in RPM about 15 seconds or so into the warm up. I also noticed that when I power up the sled the needle is real jerky compared to my other sled, which is very smooth. Recently, I encountered problems with the speedometer in my 1976 911. The circuit that resulted was not doing any battery charging, but it made nice tach pulses. I explained that on Winnipesaukee. It's running beautiful. I need help, I installed a new CW tach. Since needlefish swim near the surface, they often leap over the decks of shallow boats rather than going around. I have had this issue for a few seasons that it jumps. You can even have them set it to your current time for a fee. I first noticed it immediately after launching the Mac last year for the summer. Very simply put: The more pulses they see, the more charge they dump in a capacitor, the higher the output voltage, the more the needle goes up. When I give it gas it goes back to normal but when I let off it bounces all over. This can happen on acceleration or deceleration. 1955-72 SPEEDOMETER REPAIR Parts Needed: 37-32 Odometer Decals 1955 37-33 Odometer Decals 1956-72 06-74 Instrument Cluster Decal Set 1957 06-77 1957 Speedometer Needle To order parts call 1-800-456-1957 or visit ClassicChevy. The motor was used throughout General Motor's entire production line from 2003 to 2007. I have the same problem after I get a new fuse box in. com and affiliated sites. Assuming it's electronically driven, doing a datalog will let you know if the issue is before or after the ECU. Sections of this page. Why tachometer needle jumps up and down? A cars tach jumps and runs with engine rpm. yea everything works my speedo,gauge lights, clock, clock light, etc. if you need to send your tach to us for repair, you can remove the male and female banana plugs from your tach leads and jumper them together. My Tachometer is all of a sudden not accurate. Tacking is used in a variety of ways: To easily hold a seam or trim in place until it can be permanently sewn, usually with a long running stitch made by hand or machine called a tacking stitch or basting stitch. The tachometer is still jumping around like crazy. Also, I have compared ECUExplorer's 'rpm' value versus the tach, and the tach is almost always 200rpm too high at anything above idle. Speedometer, tachometer, gauge, cable & sender repair, restoration and re-manufacture from the early 1900's through to current models are the cornerstone of our business. I have gotten stuck twice on the road since MS-II. make sure the wire is well-insulated and doesnt pass to close to anything that could pass interference. Anyone know where you can buy just a needle? The tach works just fine. probably somewhere near the tranny. The 60 cycle AC out of the wall would make the tach show 600 Rpm or if I put the other resistor on it would show 6000 Rpm. Also not likely to be a cable problem if the needle is always turning. Selecting M5 manual mode will make AFM inactive and the engine will stay in V8 mode. The hour meter is part of the tachometer. The tach does not work with the engine running: Turn the ignition on. We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon. Just wondering what kind of failure would make it do this. I read online it can be sticky cable, or sticky gears. The tach still bounces. At idle, in gear, I do not see any movement regardless. My boat is supposed to be 5000 RPM at 50 MPH. The engine RPM is running fine, however i notice that the tach is inacurte, the needle kind of floats up higher than the motor RPM is acturally running. An easy way to check for this problem is your needle doesn't always rest at 0 mph. The tachometer needle does not require a stop pin at zero. In addition, using a reproduction tachometer kit from Eckler's will add authenticity and value to your Chevy. I have an 04 rev. Your tach seems to be nearly following the cycles. Instrument Panel problems of the 2005 Chevrolet Silverado 21 problems related to instrument panel have been reported for the 2005 Chevrolet Silverado. one of my club's C172s got a new engine (Current Tach:60ish?). This year, the needle wont move at all - sits on about 800rpm all the time. Tach started to jump with no sign of misfire then the mis started to show itself. Ecklers Corvette parts carries replacement and reproduction speedos, tachs, odometers, pointers, needles, lenses and bezels to make replacement in your Corvette much easier. The old tachs have. We make replacing your Harley-Davidson gauge easy. I noticed that my tachometer needle is jumping around frantically. These tachs work as charge pump based pulse counters. It is electric start. The speedometer has similar symptoms: The needle fluctuates, sticks in one position, will not return to zero, will not register past a certain speed, reads slow or fast, the odometer does not register or it also just does not work. I notice all the gauges going nuts. I get power to the tach in that it jumps to a false reading of about 2500 rpm, but is unresponsive to any throttle inputs. With the tachometer wiring diagram in front of you, check the underlying connections. '80-86 use the same case for tach & non-tach, with a blank face for non-tach. I cracked the cosmetic housing also, any bright ideas on where to get one of those too? I found a site to buy it new for $70, obviously prefer to get it cheeper. I need help, I installed a new CW tach. If you are running a Magneto, you MUST make sure that you are using suppression core spark plug wires. Bike Fitment: Harley Davidson Dyna. The tach normally should read between 2-3k RPM. i have an old tachometer from a gmc vehicle, it goes to 5000 rpm, 10 20 30 etc. This doesn't happen all the time, but only every so often. They do not go up or down together but instead at random. Looking through the paperwork he gave me, he had been reading about Zero. Everything was cleaned, everything is very solid feeling, cable is new and oiled, fittings are tight. it never did this before, it is a 1996 Monte Carlo. Reads about 350 at idle (low) and about 2400 when I shift (which is normally about 2100). It is often described as "bouncing" tach. If your tachometer needle is jumping erratically or not working at all, its most likely your tachometer cable. Running down the road at 55mph and the tach will jump from 2200 rpm to 4K rpm then fall to 1k rpm or zero. I checked both tachs on another car and both worked fine. I was told by zip corvette center that this is due to the disconnection of the filter , but there is no replacemnet filter available. com is a web based support system which provides a common access point for locating key Information - Education - Support for their Rotax Aircraft Engines such as the Rotax 912, Rotax 914, Rotax 912 iS, Rotax 915 iS, Rotax 503 and Rotax 582. I just learned to live with it since I knew the engine was running steady. If this happens, remove the timing belt cover and clean the face of the optical sensor. I cannot seem to figure out why my tach needle jumps all around. If the gauge does not respond, there is likely a break in the wiring between the fuel gauge and the sending unit. My tach needle starts jumping around when I am under hard accelration. Hi, I'm a new member that has spent the last 6 months restoring a 1958 Wurlitzer 2200, Mechanically all is running well and I am presently re-buying all those old 7" records that I used to own. Search Fixya. A Here is a write-up on the initial steps in tracking down a speedometer and/or tachometer problem. As far as electronics go, what would make the tach needle jump so much? It's just so weird. inside the tach, 4 wires ran from the circuit board to the tach needle motor assembly, and I just tried all different combinations of wires until it ran right. Only been out once so far this year due to bad weather, other commitments etc. When it is idling, the speedo needle jumps from from 0 to 120. This "zeros" the tach and then I just carefully stick it back on. Basically when I am at 2500 and gas it the needle just bounces around and cannot tell what rpm I am at. I've got mu Autometer guage all mounted into my car and all and I have everything operational but my hook up to the coil to actual get my read out. 1999 monster 750. The part number is N 02 070 109. Re: speedo/tach needle shaking or bouncing Solution (ozglxvr6) 12-22-2003 04:21 PM #6 Have no idea, I know one thing though, to adjust the needles i spinned them till they indicated "0" - maybe this cause the problem. I solved it by jumping a small dash light bulb around the voltage regulator. This can happen on acceleration or deceleration. Turn the tachometer over gently so that the backside is exposed. The tach is a very simple worm gear mechanism. I've figured out that if i stop (in a safe place, of course) and cut the. Hope yours turns out to just be a lubrication. When I give it gas it goes back to normal but when I let off it bounces all over. My Pathfinder ST (Australia version), since new the needle of the tachometer always fluctuate up and down small amount. When some resistance is indicated (see specifications), that will be the approximate location of the break in the carbon-core. These tachs work as charge pump based pulse counters. Cleaning the tach wiring connections (all of them) is the real fix unless there's a problem with your tach or with the wiring running to the tach. I popped a couple in my transmitter just to see what would happen. if you need to send your tach to us for repair, you can remove the male and female banana plugs from your tach leads and jumper them together. STUCK OR JUMPING / BOUNCING / ERRATIC TSB 07-11-2 SPEEDOMETER AND/OR TACHOMETER FORD: 2005-2007 F-Super Duty This article supersedes TSB 06-7-4 to update the Cluster Concern vehicle model years. It did it for a few hours until the tach frooze and broke the cable. The only danger here is that you might bend the needle pointer/tail, so it is best not to touch that part of the needle. it doesn't do it all the time and when slowing down the needle on. The truck dies at a stand still when engaged in Drive or Reverse. Your OM schematic shows that the tach signal is generated inside the Dinoplex ECU so it is possible that only that section is bad, and the section running the coil is still OK (since you report that the engine seems to rev properly and smoothly), but I'd give that a lower. It uses computer pin # 4, a Dark green/Yellow wire: the wire has a 22K Ohm resistor inside the wiring harness between the TFI module and the computer. Not sure what its all about, but its not something I noticed till I read this and it made me look at it. Last season near the end my tach would start bouncing after awhile. If your tachometer has no signal or an erratic signal (pointer jumping all over) you first need to verify that you have correct power, ground and signal connections. Re: Tachometer Needle Jumps Super simple change, two yellow wires on top(stator leads) a gray wire (tachometer lead) and a red wire (charging lead) Two mounting screws attach it to the mounting plate on the side of the outboard. I have a 5 Inch autometer Tach and when I cruise down the freeway at steady speeds 60, 65 mph the Tach needle starts jumping from 2500 to 3300 back and forth. also the tach needle bounces now too. Unscrew it from the Tach and look at the end of the cable, it should be square and not rounded off. The engine appears to run fine, although there is some popping (I think it's because of the straight-through exhaust). The tach does have a maximum RPM mode and it knows the time and can thereby keep track of run hours. Very simply put: The more pulses they see, the more charge they dump in a capacitor, the higher the output voltage, the more the needle goes up. The higher the duty cycle of the pulses, the more the needle moves. I took a slide on my gen 1 SV650 naked this weekend, somehow breaking the tachometer needle. If im shifting hard and really getting the most out of my engine only taking it to like 3 rpm it will go all over the place then stop working and the needle stays at 0 mph. Have the torque converter and tranny flushed. This started after putting in a new battery and trickle charging it. I checked both tachs on another car and both worked fine. Hi, the other night I had my car out and it started revving high. 5mm above and 1-1. There seems to be lots of stuff in the archives about this but does anyone have a quick solution. The tachometer needle spinns around or show wrong.