Just curious is anyone knows what the signs or symptoms would/could be for a bad PCM?
First of, it's not my Dakota, it's my fiance's truck, 96 S10 Blazer, 4.3L V6. I also wasn't with her when it happened, but I've done a small amount of diagnosing and I think it might be a PCM problem.

Here's the situation:

She was driving everything was normal, then her CD player started skipping like it was cutting in and out, then all her Cluster idiot lights came on, but the Engine was still running (It didn't cut out), then CD Player turned back on, and all the cluster lights shut off and went back to normal.
When she got her she told me what happened, and I went out to truck, opened the door and turned the key, and got nothing. No power anywhere at all. Nothing, no lights, no buzzer, nothing.
I checked battery voltage and got 13.4V-ish (A little on the high side).
I disconnected the battery and took it out. While it was out, I checked the PCM fuses, and all were good.
I reconnected the battery, about 5 minutes later, and immediately had power again. Checked battery voltage again, and it was down to 12.8V. I started the engine, no lights (Obviously - I reset the PCM), full power, everything was normal. Checked Charging voltage and got 14.23V. Normal.
So this is where I get stumped.
I ran down to Advance and had them check the battery, Alternator and Starter. Alternator and starter checked fine, but the battery came up as bad. However, the battery looks new. I'm pretty sure the battery was replaced when we bought the truck, about 3 months ago.
Here's the kicker. When he was trying to connect to the battery, it kept telling him to check for something that's on, like Key on engine off, radio on, etc. But nothing was on, and the key was in my hand. The only thing that was on was the under hood light.
So I'm thinking there is a parasitic draw on the battery, probably from the PCM.
Does this sound correct?

Also, I can't remember how to check for a parasitic draw. Can anyone explain it to me? I haven't done it in so long, I just can't remember.

 

hold a volt meter between the positive post and positive battery cable, so anything drawn goes through volt meter. start yanking fuses from there till you have 0 draw.

FYI, radio and computers are the only things with a direct B+ lead i think...

 

^^ Thats how I thought it was done. I'll give that a shot see what happens.

 

FYI, according to the 2001 Dakota service manual (I know your working on a '96 Chevy), the typical ignition-off draw (parasitic draw) is between 5 to 35 milliamperes. (.005 to .035 amperes)
For the '96 Dakota, the service manual lists .005-.020 amperes.

In the 2001 Dakota service manual, it has a table of typical parasitic draw (page 8F-16). The '01 Dakota PCM is listed as 0.95 milliampere. (.00095 ampere).

Oh, and you need to make sure you are using a multimeter than can measure load. Not on the voltmeter function.

 

^^ it can. It's a Fluke 78. I've done this kind of stuff in the past, but it's been awhile. I hate working on Electronics. I'm more of a engine kind of guy.

Will look into the amp draw, but it'll probably be later.

 

Yea, chasing wires sucks.
It's worse where I work, because it seems that, wires always break in the worst spots. Tens of man hours spent removing stuff for one wire. Gotta love aircraft!

 

^^ Yes it does indeed. I would hate to work on aircraft, Cars are enough of a pain. Planes have what 3 or 4 times the amount of wiring and electrical stuff in them? God damn, thats a nightmare just thinking about it.

 

I think i read an F-16 has like 5 miles of wiring? and a 747...i dont want to think about?

 

Yeah, that right there is Hell of earth for me. F that. I'm too much of a mechanical person to deal with that ****.

 

Problem solved. Bad positive battery cable.

It actually did it to me this time when I went to put gas in it. Went to turn the key and got nothing. It went click, and then nothing. I knew what that was immediately. Narrowed it down to bad positive cable. All is well now.

Thanks guys.