4L80e behind LY6?
Thread Starter
Teching In
Joined: Aug 2013
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4L80e behind LY6? I have a 07 LY6 6.0 I'm swapping into a 89 s15. I have the entire engine harness and e38 computer. I never seen the vehicle it came out of but I was told it was a truck. From what I can find every nnbs HD truck came with the 6L80e and vans could have came with the 4L80e or 6L80e. How do I find out for certain which trans was behind this motor? From some searching I've done they're not easily interchanged so the harness should be different. If it turns out the harness is set up for the 6-speed what's the cleanest most cost effective way to use the 4L80e? What years 4L80e's do I need to look for? Some of the threads I'm finding through Google are pretty old they talk about having to use an older computer and parts of the harness as a stand alone to only control the trans and a separate one for the engine. I would think it would be easier to convert the entire motor over to use an older harness, dbc throttle body, and eliminate the vvt than to have two computers and harnesses.
I think in 07 the trucks came with 4L80's but I'm not 100% sure on that. The post above is correct. The 4L80 will have the circular plug and a TCM. No plug/TCM means 6L80 since the TCM is inside the 6L80.
Your best bet is to buy a new harness setup for the 4L80e and the TCM.
Your best bet is to buy a new harness setup for the 4L80e and the TCM.
Thread Starter
Teching In
Joined: Aug 2013
Posts: 13
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Ok. Finally got a chance to look at my harness again. No tcm attached to the ecm like I've been reading it should be and no connector close to it that would be for one. And here's the plugs I'm working group with. PSI sells the harnesses for 58x truck motors with a 4L80e for 750. Then it's 140 if I recall for the tcm. Will any t42 tcm out of a junkyard work after being programmed? Then I still need to get a pedal, maf, o2's and extensions, and the transmission itself. Thought I was done with all the big spending....
TECH Fanatic
Joined: Jan 2015
Posts: 1,114
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From: Fort Worth, Texas
Your harness is set-up for a 6 speed auto, Buying a harness is your best bet, Not a fan of PSI, I can build a better harness, And I don't build harnesses....Give Bill @ BP Automotive a call, His S-10 harnesses are VERY NICE & Plug & Play!
