dielectric grease will be good.. apply liberally to the contacts maybe twice...did it fix your issue?

I haven't tested again yet. I gotta run for a bit so I'll finish it later tonight....

Sorry to not contribute to this thread, been at the Daytona show and have not looked at a computer for a week............

When the car was swapped to a V-8, the tach was most likely modified for accuracy. The stock tach will work perfectly with the 3800 as they are both sixes. If the tach you have was modified, you either need to have it modified again, or just find a six cylinder tach.

Forum member JGunsett is a great source for tach work.

When you check CONTINUITY (not RESISTANCE) between the tach and the ICM plug, put one probe on the metal tab on the flexible circuit on the instrument cluster, not at the instrument cluster plug, I have seen the tabs not make contact with the flexible circuit traces.

The tach signal from the ICM goes directly to the tach and is not shared, the ICM also feeds info to the PCM and the PCM derives its own tach reading based on other info. The reason the engine harness had no tach wire is because the donor car had no tach, therefore GM did not include a tach wire from the engine/ICM connector.

Removal of the screen below the engine grill would not affect how dirty the black paste has gotten, that paste is over 20 years old and probably has nothing to do with your issues.

PM me if you need more help, should be a pretty easy fix.

Joe

Ok. I bought another Tach off ebay to rule that out. Before I install it I'll check continuity again like you said. Thanks.

Just put new tach in and still nothing... Uhhhggg!! Now what should I do? Maybe the coil isn't putting out juice for the tach?

Something heated that up and caused the open.........

You can probably tin both sides of the break and solder a small jumper over the gap.

quote Originally posted by olejoedad: Something heated that up and caused the open......... You can probably tin both sides of the break and solder a small jumper over the gap.

I've never used tin/tinned anything is that used for copper piping?

Do you think that break is causing the tach issue?

it looks like it feeds that light bulb

Found a short. Maybe this caused the problem...

[This message has been edited by BAD88GT (edited 04-06-2012).]

Glad you got it fixed.

"Tinning" refers to applying solder to both surfaces that are to be soldered together, prior to making the actual connection. After each part is "tinned", it takes very little heat to perform the actual connection.

quote Originally posted by BAD88GT: Fixed the break and short. Tach works now. Thanks everyone.

This is probably what's wrong w/ my tach or might be what you initially thought it was @ tach setup for 4cyl. Will take it out and check. Thanks for posting your symptoms, diagnosis, and resolution and thanks everybody for the input. Sheesh, I love this forum.

quote Originally posted by olejoedad: Glad you got it fixed. "Tinning" refers to applying solder to both surfaces that are to be soldered together, prior to making the actual connection. After each part is "tinned", it takes very little heat to perform the actual connection.

Good to know. I was never shown the " proper " way to solder. Maybe that's why I sucked at it...HEHE. Thanks.!!!

just saw you got her fixed... awesome to hear