Mine jumps occasionally as well
Jumpy tachometer, any fixes
- Thread starter Nickslexi
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My tach started to misbehave just after I swapped in a Tercel "high output" alternator. However the needle only drops when I have my headlights on, and then only when I use my turn signals or step on the brake.
I am thinking it must be a short in the wiring off the alternator (this is where the tach receives its RPM info, yes?), after I moved around the 20 year old (read: brittle)?) wiring.
I am thinking it must be a short in the wiring off the alternator (this is where the tach receives its RPM info, yes?), after I moved around the 20 year old (read: brittle)?) wiring.
Have you figured out what was causing your tachometer issue?
I have the exact same problem on my '96 HDJ80. The tach needle drops as soon as there is load on the electrical system - turning on headlights, high beams, airconditioning, turn signal, rolling down windows, stepping on brakes.
When I'm driving at night with just the low beam headlights and airconditioning off, the tach needle is okay and reads the correct rpm. As soon as I switch on the airconditioning, the needle drops at idle but will start working once the vehicle is up to speed. With the headlights, aircon and fog lights or high beams on, the needle will drop to zero rpm even while driving at speed.
I fixed the issue on mine thanks to this post: http://www.offroad80s.com/1hd-t-tacho-t913.html
The connection to the body ground/earth of the thin cable running from the negative battery terminal was loose as stated in the link above. Tightened it up and all is fine now. Tachometer does not drop anymore even with the headlights, fog lights, front and rear air conditioning, turn signals and brake lights are on. Very happy now
Now that I think about it, mine has not acted up since I replaced my battery and upgraded all my cables, including that ground wire...weird
Ooh good point, I forgot that my battery lugs were cracked right in half so I bought some new ones.
I'll check that side of my electrical!
In the end it was a ground wire. What I thought was the last vestige of non-functioning aux driving lights that were on the damage multiplier that came with the cruiser. I left it disconnected when I changed the battery lugs. As soon as I connected it back to the battery, the tach stopped jumping.
Old thread, but I have this too. Almost always right around 2100 RPM. It doesn't do it all the time. Here's a video I managed to get:
http://youtu.be/Iiy9M1SlsaQ
Kind of wondering if this has something to do with it:
http://www.clublexus.com/forums/ls4...lved-ecu-leaking-capacitor.html#ixzz3Ta141rDC
Thanks Bugsnbikes for bringing this to my attention.
http://youtu.be/Iiy9M1SlsaQ
Kind of wondering if this has something to do with it:
http://www.clublexus.com/forums/ls4...lved-ecu-leaking-capacitor.html#ixzz3Ta141rDC
Thanks Bugsnbikes for bringing this to my attention.
Mine just stopped working all together...
Thanks. Sounds like the consensus is that the tach is the problem, though I'm still skeptical of many of the "fixes" posted. At least in my case it will go months without doing it, so something that initially may appear to fix the problem may actually just be a coincidence.
My tach was lurching, also around 2000rpms, one cold damp morning a few years ago for 20-30 minutes IIRC, then nothing until last week when it appeared to do a micro-drop/lurch maybe twice. I've picked up a spare instrument cluster for the day the tach dies but in the meantime plan to recheck as many grounds I can get to.
Almost a decade after this thread was started I can add my 2c and say that I am having the tacho issue. However mine seems a little more serious, when my tacho dives for the bottom (never up, always down) I get a corresponding loss in power. Complete loss in power, feels very different to a single cylinder misfire.
I think this points to the fact that my tacho is probably fine and is taking its readings correctly from the igniter which is the issue. Can anybody please confirm for me if the 1FZ does indeed take it's RPM reading from the igniter?
I think this points to the fact that my tacho is probably fine and is taking its readings correctly from the igniter which is the issue. Can anybody please confirm for me if the 1FZ does indeed take it's RPM reading from the igniter?
Sounds like a faulty ground.
Thanks for the reply.
The igniter is earthed straight through its mounting bracket and I have never removed it so there shouldn't be any issues there. Also I believe the issue is too intermittent to be a faulty earth, only occuring when the car is almost at full temp (as judged by water temp gauge in top radiator hose not factory gauge). I also know that the igniter has two different resistance settings based on temperature. I am guessing it is having trouble switching between those two settings and thats when I get this loss of power.
In any case, I have already purchased a new igniter and will be fitting it tomorrow.
The igniter is earthed straight through its mounting bracket and I have never removed it so there shouldn't be any issues there. Also I believe the issue is too intermittent to be a faulty earth, only occuring when the car is almost at full temp (as judged by water temp gauge in top radiator hose not factory gauge). I also know that the igniter has two different resistance settings based on temperature. I am guessing it is having trouble switching between those two settings and thats when I get this loss of power.
In any case, I have already purchased a new igniter and will be fitting it tomorrow.
Check your battery terminals, remove the cables clean them then reinstall. I've seen some cases where the terminals didn't look bad but once you popped the cables off it was evident that there was massive corrosion between them.
I'd start with the simple things before you start throwing parts at it. I have been in the same position as you before and thought that it had to be x part, only to replace it and have it make no change on the issue. That method of troubleshooting can quickly become very costly.
I'd start with the simple things before you start throwing parts at it. I have been in the same position as you before and thought that it had to be x part, only to replace it and have it make no change on the issue. That method of troubleshooting can quickly become very costly.
Hey Friend, Question for you. Is there a connection where I can plug my dwell into to test my tachometer(tach not working at all) on my 91 fj80? I tried to at the igniter but the engine wouldnt start since that plug is versatile. Appreciate the input.
The very first thing I do when I buy a car is clean or replace the battery terminals. Same thing for any troubleshooting I need to do.
Start with the battery and move down-stream.
I just noticed this on my '96 3 weeks ago. Only happens when stopped and tach will jump down to 200 RPM then back to normal. Engine isn't changing it's idle.
No big deal, just more character.
No big deal, just more character.