I am doing my tranny swap on Wednesday this week. I have already done the pedal swap and have it hooked up so that I have to press in the clutch to get the car to start. I have a T5 harness but wondering if I have to use it. I understand that I can take the connector from the T5 harness and connect it to the auto harness for the reverse lights and NSS bypass.

My question is what is the connector in front of the T5 with a wire/connector. I see the connect on the harness but is it necessary? I guess what I am asking is do I have to swap the harness or can I get away with hooking the reverse lights and bypass the NSS?

I've read that people have done both it seems, changing the entire harness or just wiring in the part that is needed.

Which is best?

 

Ok, I am dying to ask questions about all of this to double check what yoru talking about , but I will keep it simple and just answer what it does , and you can decide.

That plug tells the computer what gear the trans is in. Much discussion out there about the importance of it. Everything from load based calculation to only being for running codes. On first year WC cars it was only for the upshift light LOL.

Just as an FYI, if you planned on swapping to an A9L, dont. Again, not going to get into a way, but there are wiring differences with pin #30 that will fry an A9L if swapped onto an auto harness. Look into it if you have not heard this before.

 

That is the neutral safety switch on the front top of the t5. If it is unhooked or malfunctioning it can/will throw a code 67. This code causes an irratic/rolling idle and can cause the car to stall. It also allows the car to run the KOER test. If it is malfunctioning it will not run the test because it can not tell that the transmission is in N....


As for frying the computer...it can happen but doesn't always. OP, do your research if you really want to run a A9L BUT the A9P will work just fine

 

I dont think we disagreed on any of that, just different perspective. Technically though, its called a neutral input. Auto's have the "safty switch" located in the trans, manuals at the pedal. Remember , not all t5's even got this. New Tremec T5's and TKO's dont even have it, and how many of those are out there. I just hate saying something for certain, when I have seen so many not have an issue.

 

Thanks for the help. I am going to go ahead and run the T5 harness and hope for the best. I am installing the T5 tomorrow. Wish me Luck!

 

FWIW....

I have done about 30-40 of these swaps, and am the local guru on wiring. I have always used the T5 harness. Just not worth the bother , especially when you have it sitting there.