Wire Harness Differences - SS/SC vs. SS/TC?

Desert Sasqwatch

Well-Known Member
I have been trolling thru the threads in the electrical section and I have not found anything definitive to answer the question of differences between the wire harnesses. SS/TC cars are harder to find - and more expensive - than SS/SC cars. Attempting to use a SS/SC donor for a SS/TC build may become the only alternative for some of us. Short of pulling the electrical manuals for the SC and TC wire harnesses, has anyone had experience with this? Can the SC (or even NA) harness be used for a TC build with some modifications?
 

BaltimoreHokie

Well-Known Member
I cannot comment on the differences but I believe they are some. I think one Brian (LINK) was taking his SS/SC harness and re pinning it to be used for an crate motor LDK. He has some write ups on his build thread.
 

Brian74

Well-Known Member
You literally need to print out all of the ECM and BCM pinouts and wiring diagrams for each vehicle and match them up. Some wires will be added, some removed, and some repinned. I highlighted the ones I found that needed to be changed and added notes. It wasn’t terribly difficult. The hardest part was completely repinning the new ECM connector and figuring out what additional connectors and pins to order (ie: body harness to engine connector).

There is no definitive or precise way of doing it because some of the added circuits can be utilized or wired up in more than one way.

If you check your messages, I sent you a link to the AZ public library a couple weeks ago, where you will have access as an Arizona resident. The Chilton manual has all of the wiring diagrams you’ll need and includes most of the part numbers for the connectors.
 
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Desert Sasqwatch

Well-Known Member
Brian, thank you. I was afraid someone was going to say that. Will need to put my EE hat on and roll up my sleeves to figure this one out if I don't end up with a TC donor. Did see the link, have not tried it yet, it should come in very handy once I am into the harness modifications. I'm sure I may be asking some additional questions as I progress. Regards, Tim
 

Brian74

Well-Known Member
No problem, will be glad to help however I can. Soon enough I will need to get my harness laid back out again and finish some minor details. That would be the best time to ask questions, lol.

I know you can use the E69 ECM, but the E39 ECM can be used as a stand-alone but tuning knowledge may be limited. Not sure what other ECMs are compatible or what tuning capabilities there are for them. With the E69, you cannot disable VATS with HP Tuners so you will need to utilize the BCM and theft deterrent module, preferably from the same vehicle.

As I think I mentioned before, you can buy an ECM, BCM and theft module out of the same vehicle from LKQ and have it shipped to your house for somewhere around $300. I never thought about asking them to ship an entire TC wiring harness because the labor is pretty intensive to remove it. I do know they had several Cobalt TC’s in their inventory the last time I looked. Hell, you may also be able to get an SS subframe and control arms, steering column, fuse box and rest of the donor parts from them out of the same TC car too but the shipping could get costly. On the same token it would negate your need to even find a donor altogether.

A stock body wiring harness from an LS could probably just as easily be modified for a TC. The pull your own yards in Phoenix have several LS models.

There is only ONE company I know of who sells the E69 ECM to body harness connector, and they are EFI Connection. It retails for about $70. The rest of the connectors and pins I needed I bought through Mouser electronics. Most of the part numbers for the connectors can be found in the Chilton manual using the connector diagrams.
 

Brian74

Well-Known Member
Several of the donor parts you can use from an LS; dirt cheap at a pull your own yard. I used an alternator and clutch/brake pedal assembly from an LS. The engine harness for the LDK/LNF can be bought brand new for $280 through GM. I can confirm its a perfect fit and match, but you’ll need the crank sensor ext. harness off of an LS and you’ll need to modify the alternator connector if using the 115 amp alternator.
 

deuc224

Member
Several of the donor parts you can use from an LS; dirt cheap at a pull your own yard. I used an alternator and clutch/brake pedal assembly from an LS. The engine harness for the LDK/LNF can be bought brand new for $280 through GM. I can confirm its a perfect fit and match, but you’ll need the crank sensor ext. harness off of an LS and you’ll need to modify the alternator connector if using the 115 amp alternator.
You have a part number or link for the LNF engine harness? Ill grab that just to have it in case i mess up the one on the car when i start to thin it out. Gonna go pick up my donor tomorrow, super excited.
 

Brian74

Well-Known Member
You have a part number or link for the LNF engine harness? Ill grab that just to have it in case i mess up the one on the car when i start to thin it out. Gonna go pick up my donor tomorrow, super excited.
From my notes I have part# 20782130 but I would check GM parts online to be sure.
 

JERMzSS

Well-Known Member
I know this isn't on topic but the fuse boxes for the ss/sc cars and the ls cars are the exact same as well. I pulled them apart and throughly check and sure enough they are. Saved me a lot of money replacing my fuse box.
 
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