Tachometer RPM's Reading Low

elemgee · #1 01-11-2018, 02:47 PM

My 94's tachometer recently started reading low RPM's. At idle, for instance, it reads around 300 rpms. When accelerating, the highest it will read is around 1,400 rpms. The engine runs and sounds fine.

Thought it might be due to the very cold weather we're having here in the northeast but its around 60 degrees today and the problem persists,

Any ideas?

Thanks.

Larry

oab_au · #2 01-11-2018, 03:45 PM

Quote:

Originally Posted by elemgee

My 94's tachometer recently started reading low RPM's. At idle, for instance, it reads around 300 rpms. When accelerating, the highest it will read is around 1,400 rpms. The engine runs and sounds fine.

Thought it might be due to the very cold weather we're having here in the northeast but its around 60 degrees today and the problem persists,

Any ideas?

Thanks.

Larry

Hi Larry, the taco gets it's signal off the ECU, so does all the other units, engine, gearbox, etc, so that should be OK.
It does have a separate ground up behind the dash, or it is seizing up.

gwynethh · #3 01-12-2018, 07:44 AM

Mine is doing the same a bit intermittently. I have a replacement unit ready for install during car work season (July1 to Aug 30 here in New England). Here is a proof of issue video. https://www.youtube.com/watch?v=JMQ1apL_uC4. Keep us informed of your solution.

Levoi · #4 02-01-2018, 08:10 AM

Yes I have the same issue, and also the speedometer is off (to low). 1 speeding ticket as a result so far..
Idle is a very convenient 0 RPM according to the tachometer...I have the idea that this does become somewhat better when driving for a long distance, so bad voltage / ground may be to blame? I don't see how the engine could run fine with a bad ECU, but honestly i'm don't really have a lot of knowledge in that department.
Please keep us posted!

Mike621 · #5 12-23-2021, 01:18 AM

Anyone resolve this issue? I'm having the same symptoms and thinking its something in the cluster.

calisvx · #6 03-03-2024, 05:10 AM

*bump* anyone ever resolve issue Sam having the exact same thing and I have no idea as its intermittent =(

Noriyasu · #7 03-03-2024, 08:47 AM

This is probably a capacitor issue. The life of the electrolytic capacitor on the printed circuit board of the tachometer is about 4000-8000 hours.

I saw a similar topic on this forum recently.

Mike621 · #8 03-03-2024, 04:08 PM

Mine turned out to be a capacitor issue. I swapped the tach out for another unit that works.

I ran into a similar behavior with my speedometer, and it was capacitors leaking, too. A friend soldered in new ones for me and my speedometer is working well again. I will probably have them repair my original tach eventually.

calisvx · #9 03-04-2024, 04:53 PM

Thanks everyone for the info! I will source the parts and solder new ones =) i was going crazy check all the electrical and not finding any problems =( i will update once complete in a few weeks.

Stevebsy · #10 03-04-2024, 07:06 PM

https://youtu.be/ujYNeFCSng4?si=frFoXyTospCMeR_2
I followed this one and fixed my tach.

Here's a couple more with the speedo too. Mine needs the speedo done.

https://youtu.be/nycVuO1O5KY?si=-Nd39EBSR7-SvGSd

https://youtu.be/lpz2lJUfCek?si=1LMCRe3hngjnvIWG

Mike621 · #11 03-04-2024, 08:07 PM

It may be worth mentioning, though unrelated to the OP: I forgot to mention that I ran into bad capacitors in my climate control unit, too. Also had a friend help me repair that.

Noriyasu · #12 03-04-2024, 08:50 PM

Quote:

Originally Posted by Mike621

It may be worth mentioning, though unrelated to the OP: I forgot to mention that I ran into bad capacitors in my climate control unit, too. Also had a friend help me repair that.

I had same experience in climate control unit.

It is well known that the 4WS controller has the most capacitor problems. I think it's because it's located in the trunk and gets hot.

Mike621 · #13 03-05-2024, 01:51 PM

Quote:

Originally Posted by Noriyasu

I had same experience in climate control unit.

It is well known that the 4WS controller has the most capacitor problems. I think it's because it's located in the trunk and gets hot.

Oof. I am not looking forward to that one. I was promised a spare when I bought this car, but that never happened. I have been keeping an eye on yahoo auctions.

Were you able to repair your 4ws computer?

Noriyasu · #14 03-05-2024, 09:56 PM

Quote:

Originally Posted by Mike621

Oof. I am not looking forward to that one. I was promised a spare when I bought this car, but that never happened. I have been keeping an eye on yahoo auctions.

Were you able to repair your 4ws computer?

I have no experience in 4WS because my Car has no 4WS. But, following website will be useful for you.

https://minkara.carview.co.jp/userid...8228/note.aspx

I'm an electrical engineer, so replacing these parts is easy, but if you're not confident, ask someone who is good at soldering to do it for you. It's basically the same job as replacing a meter's capacitor. However, the PCB pattern may be corroded due to capacitor leakage, in which case repair may be necessary.

Tapani · #15 07-14-2024, 12:23 PM

I have the same issue with the speedo... does anyone know the values for the elcos? Also for the tacho... I will replace them too while in there.

Are they all 10uF?

Thanks and greetings from Finland,

Tapani