A wiring conundrum

CopperNick

G-Body Guru
Feb 20, 2018
646
93
Canada
Think you've got problems, gimme a minute.

Okay, that solitary green wire that is hanging in the wind all by its lonesome may prove to be the harness wire for the temperature sending unit, The default location depends on a few things but typically the sender was screwed into the driver's side cylinder head between 1 and 3. Alternatively there could have been a boss for it on the original intake on the original motor. Third choice could have been one of the bosses that were part of the water neck.

The computer being connected to the 3/8ths stud on the starter solenoid is both normal and typical. Being connected there gives it direct access to power from the battery + terminal; no power drop due to distance.

One of other greens in that multiple harness may have ended up at the oil pressure switch-idiot light version. The default convention for ground is usually the black wire. DO NOT quote me on that as you might easily find that all the wires in your headlight harness at the rad cradle look to be black. They aren't but can appear that way.

Now, since all this is about wiring, that is exactly what I have been buried in for the last week!! You think classic car harnesses are bad, try a vintage one where all the wires were covered in cotton wrap and some kind of waterproofing goop. As installed they were all kinds of pretty colors;' after ?? decades, pretty much all black and burnt and stench and cracked and broken and field fixed and left. This project was one that I originally started over Five years ago. And back then it was a rehash of a wiring project that had been done in the late 70's early 80's?? None of the diagrams match what is currently present in the subsystems. Physically I can only work on it for about 2-3 hours before my back goes into spasm mode and I have to quit. Where a wiring diagram can appear as a single page, I now have 4 pages of notes detailing what goes where and the colors of the wires involved. And i am not done yet. Why bother with the updates? As cars have evolved, their various subsystems have become more complicated and the wiring harnesses have grown more spaghettied to match. As has been pointed out by several respondees to this thread, a good manual is almost an absolute necessity when it comes time to deal with old.

Given what you appear to be dealing with and the damage that seems to be apparent, it is possible that the simplest fix might be to locate a same year/same model car in a dead yard some place and see if the engine bay/rad cradle wiring harness is intact from the firewall bulkhead connection forward. You may hear this being called C100. It is located on the driver's side behind the inner wheel well and below where the wiper motor is supposed to be. To remove it there is a big centre bolt through the middle of the plug that you unscrew and then GENTLY prise the plug asssembly off its base. This is a definite patience moment because that plug will almost be glued in place with sealer so be gentle. After. or before that, you need to trace the wires that come off that plug and detach them carefully from their locations. Masking tape and a pen or pencil will be your friend as each wire needs to be tagged as to what it was attached to. Cell phone to take pictures also helps. Take the whole thing all the way to the headlights and horn. You can't easily piecemeal a newer one to gether with your current lump so a complete swap out and replacement may deliver the least amount of stress.



Nick
 
  • Like
Reactions: Cal902

Cal902

Not-quite-so-new-guy
Thread starter
Jan 15, 2021
34
8
You fvckin' done yet?! Quit typing and do something!
I was questioning the woulda, coulda, shoulda!! Didn't realize I sent that twice!
With nothing left for the computer to control, you can disconnect the computer wiring if the PO hasn't run anything through it. Shame they hacked it up like that. Through to run CCC on a SBC would have required swapping out the Cutlass computer harness and ECM for a Monte Carlo SS harness and ECM.

The trans still needs a method for controlling lockup so better check that out. Also better check the fuel pressure as all new replacement fuel pumps output too much pressure and force the needle valve open. Nobody makes correct spec 3 port fuel pumps anymore.
What fuel pressure do you think it should be putting out for this configuration?
 

Cal902

Not-quite-so-new-guy
Thread starter
Jan 15, 2021
34
8
Think you've got problems, gimme a minute.

Okay, that solitary green wire that is hanging in the wind all by its lonesome may prove to be the harness wire for the temperature sending unit, The default location depends on a few things but typically the sender was screwed into the driver's side cylinder head between 1 and 3. Alternatively there could have been a boss for it on the original intake on the original motor. Third choice could have been one of the bosses that were part of the water neck.

The computer being connected to the 3/8ths stud on the starter solenoid is both normal and typical. Being connected there gives it direct access to power from the battery + terminal; no power drop due to distance.

One of other greens in that multiple harness may have ended up at the oil pressure switch-idiot light version. The default convention for ground is usually the black wire. DO NOT quote me on that as you might easily find that all the wires in your headlight harness at the rad cradle look to be black. They aren't but can appear that way.

Now, since all this is about wiring, that is exactly what I have been buried in for the last week!! You think classic car harnesses are bad, try a vintage one where all the wires were covered in cotton wrap and some kind of waterproofing goop. As installed they were all kinds of pretty colors;' after ?? decades, pretty much all black and burnt and stench and cracked and broken and field fixed and left. This project was one that I originally started over Five years ago. And back then it was a rehash of a wiring project that had been done in the late 70's early 80's?? None of the diagrams match what is currently present in the subsystems. Physically I can only work on it for about 2-3 hours before my back goes into spasm mode and I have to quit. Where a wiring diagram can appear as a single page, I now have 4 pages of notes detailing what goes where and the colors of the wires involved. And i am not done yet. Why bother with the updates? As cars have evolved, their various subsystems have become more complicated and the wiring harnesses have grown more spaghettied to match. As has been pointed out by several respondees to this thread, a good manual is almost an absolute necessity when it comes time to deal with old.

Given what you appear to be dealing with and the damage that seems to be apparent, it is possible that the simplest fix might be to locate a same year/same model car in a dead yard some place and see if the engine bay/rad cradle wiring harness is intact from the firewall bulkhead connection forward. You may hear this being called C100. It is located on the driver's side behind the inner wheel well and below where the wiper motor is supposed to be. To remove it there is a big centre bolt through the middle of the plug that you unscrew and then GENTLY prise the plug asssembly off its base. This is a definite patience moment because that plug will almost be glued in place with sealer so be gentle. After. or before that, you need to trace the wires that come off that plug and detach them carefully from their locations. Masking tape and a pen or pencil will be your friend as each wire needs to be tagged as to what it was attached to. Cell phone to take pictures also helps. Take the whole thing all the way to the headlights and horn. You can't easily piecemeal a newer one to gether with your current lump so a complete swap out and replacement may deliver the least amount of stress.



Nick
Trying to find another one of these up here will be a real chore because the scrap yards don't keep anything back this old anymore! With covid going on we aren't allowed to go out of our own province and come back without self isolating for 14 days so, I can't even get to the nearest U-pull to look around! And yes the police do check up on us!
 

UC645

G-Body Guru
Apr 20, 2020
692
93
Kittanning, Pa
Trying to find another one of these up here will be a real chore because the scrap yards don't keep anything back this old anymore! With covid going on we aren't allowed to go out of our own province and come back without self isolating for 14 days so, I can't even get to the nearest U-pull to look around! And yes the police do check up on us!
Are you able to receive packages from the states? There’s a Cutlass in a yard fairly local to me, I could pull the harness in a couple of weeks if you end up needing or wanting it. Hell, I might have a spare or two lying around that aren’t hacked up, but those won’t be from a Cutlass
 

Cal902

Not-quite-so-new-guy
Thread starter
Jan 15, 2021
34
8
Are you able to receive packages from the states? There’s a Cutlass in a yard fairly local to me, I could pull the harness in a couple of weeks if you end up needing or wanting it. Hell, I might have a spare or two lying around that aren’t hacked up, but those won’t be from a Cutlass
Trying to get anything shipped up from the states takes a minimum of 1 to 2 months right now!
 

UC645

G-Body Guru
Apr 20, 2020
692
93
Kittanning, Pa
Trying to get anything shipped up from the states takes a minimum of 1 to 2 months right now!
18BA402F-69C8-4AA1-B712-F25197469420.gif

Well, the least I can do is get you pictures of what you’re missing. You might be able to buy the connectors still. I’ll go through my parts bin this weekend
 

Cal902

Not-quite-so-new-guy
Thread starter
Jan 15, 2021
34
8
View attachment 167003
Well, the least I can do is get you pictures of what you’re missing. You might be able to buy the connectors still. I’ll go through my parts bin this weekend
I was questioning the woulda, coulda, shoulda!! Didn't realize I sent that twice!

What fuel pressure do you think it should be putting out for this configuration?
Just checked the VIN on the car and it came from the factory with a 305 Chevy engine, eighth digit is an H! Like someone mentioned earlier up here they did that quite often!
 

CopperNick

G-Body Guru
Feb 20, 2018
646
93
Canada
RE Shipping, Strongly suggest use of USPS Priority Post with tracking. They are set up to connect with the Canadian equivalent at the border so the box has a tracking number all the way from start to finish.. Have used this method on several occasions in the recent past and it has worked well. The time frame usually works out to about a week, even allowing for the paperwork drill. If the value on the package is under a C-note, customs typically doesn't bother with it because the bite on the box isn't worth the time needed to do the processing.
 

Similar threads

G-Body Performance Upgrades

GBodyForum is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to amazon.com. Amazon, the Amazon logo, AmazonSupply, and the AmazonSupply logo are trademarks of Amazon.com, Inc. or its affiliates.

Please support GBodyForum Sponsors

Classic Truck ConsolesDixie Restoration DepotMike's MontesP-S-TSouthside Machine PerformanceUMI Performance

contactAdmin@GBodyForum.comfor info on becoming a sponsor