Electrical gremlins with gauges on 98 12 valve

[NathanJones]

Hello folks. New guy on here but longtime TDR member. I had a complete body restoration on my truck finishing with a
new paint job. All factory gauges were dead when I got it back as was the battery charging. Redid all the grounds as paint was all new inside the hood. Chased through the harness visually several times. Decided it had to be the PCM as I was out of anything else to check. Just put a new computer in it and gauges came back to life except oil pressure and tach. Any
thoughts on what could be happening here?

 

[HHhuntitall]

Ohm out the sending unit on the crank. If it's not getting signal, it's probably not telling ECM to give a signal to the gauges... I'll wager your alternator isn't charging, either.....

 

[NathanJones]

You are correct that it was not charging either. I replaced the PCM with a salvage unit and got a partial solution. It is now charging, speedometer, odometer, voltmeter, temp gauges are now functioning but no tach, no oil pressure gauge function. Additionally, high beam indicator, parking brake, ABS, and check engine lights are all lit full time. Crazy stuff, but it makes me think there was more than one PCM available for this model. Although the numbers are the same it does not seem totally compatible with my truck.
I have my old PCM in hand and am wondering if I should have it rebuilt but my fear is it becomes just a core and I receive another one that presents the same or similar issues that I have now.
Any help from those who have gone before is appreciated. This is a glitch on the tail end of a fairly major rebuild on the truck which has served me well for 400,000 miles now.

 

[HHhuntitall]

Hmm, that's odd that the indicator lights are on. That makes me think you have a chaffed wire rubbing somewhere into another one. If your PCM numbers matched, that should be the right PCM. There was only one PCM, IF I recall correctly, for the 12v, but the wireloom was vastly different for the auto transmission, obviously. As for having it rebuilt, I've use AG express in Kansas to rebuild one for a '99 24v, but I don't know if they can do those, I'd ASSume so....

The Headlight highbeam indicator circuit is pretty isolated from most other circuits mechanically, so that's what makes me think you have a chaffed wire somewhere.... Hmmm