Read this to see if it applies to you...

https://www.gmforum.com/electrical-1...1999-a-303224/

dont have anything good diagram wise, just the pcm to relay wire color is dk green/white. i would check that for a ground when the key is turned to run for a few seconds. wont stay on with the engine off though. i would swap the relays if there is one similar

Thanks, guys. Mike1995 - yeah, I keep seeing references to that ground buss. I do see that somebody ran a separate ground right there from the fuel pump connector to the frame, but I will take a look at the ground buss and clean it up anyway. That'* good info. Odd that Mother GM did that.

jwfirebird - ok; I see that on a '97 book I have but it'* not for H platform. Yeah, I will go get the right diagram. I will try the local library again. Their system was down before. It should at least show the relays and I will start there. It would be ironic if it was just a bad relay...

Engine runs great until it warms, then stumbles noticeably and almost dies. Ran electrical tests on things like TPS, MAF, and a basic look at the electronic EGR, but now I realize I should be looking at the coolant temp sensor that feeds info to the PCM. Just did that repair on an Aerostar over the summer so it should be fresh in my mind,

Mealsoon

runs good until warm sounds like icm, or cranksensor, most likely is vacuum leak. very unlikely is temp sensor. they are a problem on other cars but not hardly at all on a 3800

for the wires, unfortunately the vast majority of people just want to bypass what they dont understand and pcm grounding a relay seems mystifying to some. seems like one of simplest things to me but you would be surprised what people do instead of fixing things, usually involves more work than fixing it too

jwfirebird; yes, I will go thru and replace any suspect vacuum lines. Doubt it'* the ICM; did basic tests on that to rule it out for the no-start issue. If it is causing the hot stumble, is that a fault that could be detected with a voltmeter? Just did the crank sensor to get it running, although I went with a used one.

Is it just me, or did they engineer the belt so that it is barely serviceable? I see what you mean now by removing the spacer, but I had to remove two nuts and then the studs that they bolt to...luckily they do have small hex heads on them, although they were TWO DIFFERENT SIZES...thanks a lot GM. Electronic Chilton wiring diagrams won't open at the library; of course they are clueless as to why. If I have to, I will completely trace the wires up to the relay center on a junk car to figure out what is going on there,

Mealtime

testing the icm almost never works, because it doesnt have the heat of the engine in it. as far as the belt if you buy a good one it will last 80-100k no problem and thats a lot for most people

thanks again jwfirebird. With the belt on, I drove it for the first time, runs great, and the warm stumble seems to have disappeared. CEL still on...even if the code set due to the crank sensor failure, now repaired, am I understanding that a scanner is needed to reset and turn of the light? Next up is smog, so no way can I have that light on for that. Can Autozone do that?

Mealme

Because your car is 95, its got the OBD 1.5 system in. Some national chain mechanic shops might be able to read it, but more than likely, your going to the dealer. BUT, if your looking to just clear the light. Disconnect your battery for a minute and reconnect. Voila.

Oh wow...thanks Mike1995. Time for a meaningful discussion with my buddy of 27 years who does smogs....best I've ever seen at diagnosis, good friend to have. I'm sure he'll have some thoughts. Will advise,

Mealmonger

So the detonation sensor at the front of the engine wasn't hooked up and the connector was messed up. I disconnected the battery, spliced a good connector on the wire and plugged it into the sensor, then reconnected the battery and fired it up. The CEL wasn't on initially...but then it came on in like 15 or 20 seconds...so clearly it isn't on because of something stored in memory like the bad crank sensor. Some of the stumble seems to be back. Hey, should the EVAP canister make noise? Sounds like air, I guess. Vacuum leak there?

Mealnot