# 89 Chevy c3500 engine and wiring harness changeout



## thehvacguy (Oct 30, 2009)

Hi. My dually had the motor seize up this past winter. I bought an 89 gmc Cheyenne longbed dually. They both have 350 tbi in them. The wiring harness on my Chevy is all cut and spliced from the last guy who changed the engine. So instead of cutting the wires off the gmc engine I was planning on changing the wiring harness while changing the engine. I have a few questions though...

My Chevy has cruise control and air conditioning. The gmc doesn't. Is that gonna be a problem when changing the wiring harness? Am I gonna have to add a few wires to the gmc harness to get my cruise control and a/c to work or should the wires be there already? 

The gmc is 30 miles away in the next town and I will be taking my Chevy down there this weekend so they aren't side by side for me to compare the harness...

Also, am I gonna have to change the wiring harness under the dashboard as well to make everything work? The wiring under the dash of my Chevy looks like spaghetti so I plan on changing it at some point... But I don't know if I NEED to change the dash wiring to get my Chevy on the road to work Monday morn. If I can change it on a later Saturday while I got the bbq going that would be awesome but ill do what I gotta do. Let me know. THANKS! I appreciate any advise drone someone who knows what they are doing. I'm just an hvac guy... I wish I could afford a real mechanic but I can't.... I'm struggling like everyone else...


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## Windows on Wash (Aug 30, 2011)

How did it go?

The cruise thing shouldn't be an issue but I am not sure about the other compatibility issues.


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## thehvacguy (Oct 30, 2009)

Windows on Wash said:


> How did it go?
> 
> The cruise thing shouldn't be an issue but I am not sure about the other compatibility issues.


Right now the engine is still on the cherry picker. I haven't had much time to work on it this week. I still need to change the gearbox before dropping it back in...


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