1996 C100 wiring harness connector not matching 1997 C100 firewall

[seedcleaner]

I am working on a 1997 k3500 auto 4x4. It had a bad 5.7, so I installed a 7.4l. I used the wiring harness from a 1996 k3500 7.4l 4x4 auto.

The engine and tranny work well, but a few things aren't working, and it seems the c100 firewall connector are not the same from this 1996 wiring donor truck to the 1997 that I am working on.

Tachometer not working
Alternator not working
4x4 not working (haven't verified that the c100 connection is to blame)
I can and have found several c100 diagrams but none specifically for a 1996. I have only once heard that they too have seen different pins on a 1996. Most others say they are all the same for all years, but that doesn't seem to be the case.

Before I re-pin my connector to match it to the 1997 truck, I would love to have a 1996 C100 schematic. Any help appreciated.

 

[Schurkey]

88-98 Service Manuals

Bought a 96 service manual on a cd, and uploaded it to my computer there are 2 books with a combined storage of 750MB. I took a quick gander through the pages on the forum, and haven't seen a service manual for the 96. how and where do I upload the book 1 and 2 pdf files to help out for 96'ers...

www.gmt400.com

I haven't checked to see if the download in that link actually works.

 

[seedcleaner]

Thank you very much. I never made it to page 9 in that thread. Yes, I found the c100 schematic on Book 2, 8A-202-0. And, on paper, it does appear to be different than the later years c100 schematic. Now, I have on paper some info to look at, while re-pinning the harness.

THANK YOU!

 

[seedcleaner]

The tachometer pins don't match from the 96 to 97 truck. I relocated it to the e8 position on the engine harness side and now it works. The alternator wasn't working because its exciter pin actually got bent over from the last time the c100 connector was attached. There are a few other pins that may not match but they don't seem critical, like the VSS power steering part, and maybe a couple others.

 

[RubenGlez]

Does anyone have a bulkhead wiring diagram for 1995 or 1996 7.4 4x4? It does not match to my 1997 K1500 connector.

 

[Schurkey]

Does anyone have a bulkhead wiring diagram for 1995 or 1996 7.4 4x4? It does not match to my 1997 K1500 connector.

Download the '95 and '96 service manual sets.

 

[someotherguy]

Does anyone have a bulkhead wiring diagram for 1995 or 1996 7.4 4x4? It does not match to my 1997 K1500 connector.

If you know for a fact your harness came from a 1996 truck, look only at the 1996 manual for that info. 1995 is extremely different so don't waste your time there.

Richard