PCM Issue solved!
12-28-2005, 01:50 AM
#1
PCM Issue solved! Well as I had mentioned before there was an issue with the PCM not getting 12V for main power. It worked fine when I tore it apart but nothing when I put it all back together.
So tonite I sat down with my favorite greek novel...95 F-Body manual 2. After about an hour and a half I had found alot of good info and maybe just some that would help.
The wire that feed's the PCM main power is controled off the PCM fuse under the hood. All checks of this fuse showed power to be getting and passing 12V just fine. There is only one stop shown along the way to the PCM. Some more digging showed me that C100 was a ten pin connector sitting next to the PCM on the passenger side strut tower.
NOW about 5-6 years ago I installed a SLP fan switch. It never worked the way SLP said it would but worked when the key was on just the same. Now here I am at connector C100 AND the SLP fan switch! My first thought is the inside switch portion is not hooked up. I dig around and find the switch and hook it up. no dice. Next I un-plug the SLP fan switch completely and plug C100 the way it came from the factory. Turn on the key and the fuel pump turns on and the PCM has 12V! Plug the SLP Fan switch back in and nothing. Next I pull the fan switch connectors out to inspect them. Sure enough circuit 340 Orange is pushed out and to the side on the Female portion of the connector!
WTF! The car ran like this for years. Evidently some where along the line it was getting cross feed a power source. Now that I have corrected alot of wiring the cross feed is no longer there. I pull the pin all the way into the connector and straighten it like alll the others and plug it in. I reach inside the car and turn the key on. the Ractronix furl pump screams alive and when I twist the key she jumps to life!
I guess if I had sent the Switch back years ago I would have never had this problem. TO be honest I just did not want to pull the whole damn thing back out! NOW I have to ask myself how many other issues did this cause. I have had Starting problems for just about as long
We will see! 
So tonite I sat down with my favorite greek novel...95 F-Body manual 2. After about an hour and a half I had found alot of good info and maybe just some that would help.
The wire that feed's the PCM main power is controled off the PCM fuse under the hood. All checks of this fuse showed power to be getting and passing 12V just fine. There is only one stop shown along the way to the PCM. Some more digging showed me that C100 was a ten pin connector sitting next to the PCM on the passenger side strut tower.
NOW about 5-6 years ago I installed a SLP fan switch. It never worked the way SLP said it would but worked when the key was on just the same. Now here I am at connector C100 AND the SLP fan switch! My first thought is the inside switch portion is not hooked up. I dig around and find the switch and hook it up. no dice. Next I un-plug the SLP fan switch completely and plug C100 the way it came from the factory. Turn on the key and the fuel pump turns on and the PCM has 12V! Plug the SLP Fan switch back in and nothing. Next I pull the fan switch connectors out to inspect them. Sure enough circuit 340 Orange is pushed out and to the side on the Female portion of the connector!
WTF! The car ran like this for years. Evidently some where along the line it was getting cross feed a power source. Now that I have corrected alot of wiring the cross feed is no longer there. I pull the pin all the way into the connector and straighten it like alll the others and plug it in. I reach inside the car and turn the key on. the Ractronix furl pump screams alive and when I twist the key she jumps to life!
I guess if I had sent the Switch back years ago I would have never had this problem. TO be honest I just did not want to pull the whole damn thing back out! NOW I have to ask myself how many other issues did this cause. I have had Starting problems for just about as long
We will see! 
12-28-2005, 02:10 AM
#4
hmmmmm....now you have me thinking bout the 93' - ever since the new harness went on and we TESTED it the same issue might be happening even with it all stock. I'll check and see if I can, beats the hell out of putting in a new fuel pump.
So? When do we all get to see it run?
So? When do we all get to see it run?
12-28-2005, 10:15 AM
#5
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That's cool Ellis. I'm hoping to stop by today or tomorrow to hear this beast roar. But I'll tell you one thing, looking at the elec schematics for Mikes issue opened my eyes. I never thought all this **** was tied together the way it is. The shop manual I got from Todd rocks! It shows everything (IF you can trace the signal thru the 47 different pages).
PS I dyno tomorrow morning @ 9
PS I dyno tomorrow morning @ 9
12-28-2005, 12:21 PM
#6
Originally Posted by WAHUSKER
That's cool Ellis. I'm hoping to stop by today or tomorrow to hear this beast roar. But I'll tell you one thing, looking at the elec schematics for Mikes issue opened my eyes. I never thought all this **** was tied together the way it is. The shop manual I got from Todd rocks! It shows everything (IF you can trace the signal thru the 47 different pages).
PS I dyno tomorrow morning @ 9
PS I dyno tomorrow morning @ 9
I still need a different pigtail for the tranny - the one I got has a limiter on it - stock I didn't and it sucks.
12-28-2005, 02:45 PM
#7
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When I was hooking up the wiring for my pickup (L98) I had a heck of a time.
I got it all hooked up (or so I thought) and cranked, and cranked. It would stumble to life a few times, but most of the time no dice. I hunted and hunted (and tested and tested) for a problem. Well it ended up being that the computer wasn't getting 12v while it was cranking. The circuit that I had the computer plugged into while cranking went to zero, and when I let off the key (back to the run position) the computer would then get 12v and the engine had just enough momentum to fire up. It was a pain to diagnose, since it did start a few times. Yeah, that was a fun week or so of trying things.
I got it all hooked up (or so I thought) and cranked, and cranked. It would stumble to life a few times, but most of the time no dice. I hunted and hunted (and tested and tested) for a problem. Well it ended up being that the computer wasn't getting 12v while it was cranking. The circuit that I had the computer plugged into while cranking went to zero, and when I let off the key (back to the run position) the computer would then get 12v and the engine had just enough momentum to fire up. It was a pain to diagnose, since it did start a few times. Yeah, that was a fun week or so of trying things.
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12-28-2005, 03:07 PM
#8
Originally Posted by Ackattack1
When I was hooking up the wiring for my pickup (L98) I had a heck of a time.
I got it all hooked up (or so I thought) and cranked, and cranked. It would stumble to life a few times, but most of the time no dice. I hunted and hunted (and tested and tested) for a problem. Well it ended up being that the computer wasn't getting 12v while it was cranking. The circuit that I had the computer plugged into while cranking went to zero, and when I let off the key (back to the run position) the computer would then get 12v and the engine had just enough momentum to fire up. It was a pain to diagnose, since it did start a few times. Yeah, that was a fun week or so of trying things.
I got it all hooked up (or so I thought) and cranked, and cranked. It would stumble to life a few times, but most of the time no dice. I hunted and hunted (and tested and tested) for a problem. Well it ended up being that the computer wasn't getting 12v while it was cranking. The circuit that I had the computer plugged into while cranking went to zero, and when I let off the key (back to the run position) the computer would then get 12v and the engine had just enough momentum to fire up. It was a pain to diagnose, since it did start a few times. Yeah, that was a fun week or so of trying things.
Do not feel bad. that is a very common problem when doing that conversion
TODAY I have been fitting a BeCool radiator
Expect to see changes and updates with future models 
12-29-2005, 12:36 PM
#10
Originally Posted by howierd42
I have Thursday off with nothing to do. Maybe I'll zip out to see it and give you a hand (like I really know my way around one of these things).
Trust me, you don't want to know unless its broke. Its like showing a card trick to a dog the first time you find how its wired up.