2nd Gen Non-Engine/Transmission Guage, Tach, Erratic

[Jerky]

My brother has a 97 diesel with about 140k on it. Yesterday the Guages,tach,chk eng light started getting very erratic. He says just flashing pegging and all that stuff. I was wondering if anyone else has had that happen to them. He lives in Indiana and I am in Idaho so I can't help him much. Thanks - Dean M

I just goofed and put this post in the 12 valve area as well.

 

[CBeeman]

mine did that once. the plug for the speed senser was loose

 

[Threlkeld]

I've seen it happen with a bad battery connection as well.

 

[Dave M]

mine did that once. the plug for the speed senser was loose

I agree with a bad speed sensor (sometimes called a crank position sensor). I just had the sensor go bad on my 97. I had no generator charging, no tac, no check engine light etc. I thought it was the PCM so I replaced it and it was the sensor. All those functions you are missing come thru the PCM but without the crank (speed) sensor the PCM won't work. It could be a bad/loose ground to the PCM, or loose connections at the PCM. It has 3 connectors on it and the PCM is on passenger side of engine compartment on firewall. You could try disconnecting the plugs and reconnect them but I would disconnect the battery first.



The PCM cost me $550 + 100 core from dealer. The sensor cost me $75 from NAPA. If you need a PCM I still have the one I bought from dealer and will consider selling it to you.



Try checking the crank sensor. It mounted above the engine dampner and has a pigtail connector on top on engine near the center. Could be a bad connection/dirty. Pull the sensor and clean it and reinstall.



Here is a link to my thread:



https://www.turbodieselregister.com...ons/184945-electrical-woes-maybe-bad-pcm.html



Good Luck,

Dave