wiring harness info needed

I pulled a complete wiring harnes out of my 88 xj and pulled the complete harnes out of a 89 xj for my swap. Here is my problem the 89 harness was from an auto and my 88 is a standard. i found a grey box i believe to be a Transmission control unit on the inside of the cab under the dash on the passenger side. can i still use this harnes and just leave this box unpluged ? Or am i entiring a whole new wrold of problems by doing so ? Is there any wires that must be conected in a bypass ? thanks again

:scottm:

could i just leave it pluged in ?

Not going to work need manual harness, tryed it and doesn't work.

That grey box (pax side, behind the lower panel, under the glove box?) is the TCU. I believe that the auto harnesses were largely similar to the manual harnesses - note that you also will have two connectors for the TPS (the auto used a "two-in-one" sensor, with half for the transmission) and the second connector - the four-pole one - will go unused.

You may or may not have trouble otherwise - I think the "C101" connector was deleted sometime in 1988 or 1989 (the bulkhead connector,) and you may have to work around that.

I wouldn't bother to leave the TCU plugged in - there seems to have been some difference between the auto and manual ECU, and if that is true, the ECU may look for inputs from the TCU that it won't get (if it's not there, it will probably think you have a manual - which is true. I can't verify this at the moment, however - I'm workin' on it!)

If you can post a pic of that connector you're asking about, that would help. The only ring lug that should be on the back of the RENIX alternator from the factory should be the 6m/m ring for the battery output post - the regulator connector is a non-standard Delphi Weatherpack. The other end will seem strange (at the starter motor relay) due to the segment of 10AWG fusible link wire - the rest of the lead is a 6AWG wire.

MiNi Beast said:

Not going to work need manual harness, tryed it and doesn't work.

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Ah. Any idea why it didn't work, or did you check it out?

I have a stupid question as to why it would not work. I had a manual harness in my XJ then converted to an auto. I simply added a couple of wires. Even the manual computer will work with an auto. The biggest difference is in the ability to step up the idle when in gear. I have the schematic and they look pretty much the same. Many manual tranny models even came with the plugs for the auto.

old_man said:

I have a stupid question as to why it would not work. I had a manual harness in my XJ then converted to an auto. I simply added a couple of wires. Even the manual computer will work with an auto. The biggest difference is in the ability to step up the idle when in gear. I have the schematic and they look pretty much the same. Many manual tranny models even came with the plugs for the auto.

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Tom - can you email me those schematics? I think I have them somewhere, but too much has been going on for me of late, and my Archives are in disarray...

My addy will be fine, if you don't have my other one.

i would love a copy of those aswell. thanks for all the input. i'll get pics asap

5-90 said:

Ah. Any idea why it didn't work, or did you check it out?

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Well I had auto harness to swap in place of my junk manual harness from a flood, so I buttoned it all up got the the plugs where they were to go, and just left the tranny plugs unhooked thinking that there would be no difference, but it did'nt work. So went to check it out at alocal shop, they build racing cars and do all their own wiring and was told they was the place to go, I was considering having them make me a new harness. So I told them I had an auto harness and instantly he told me it would not work. I told him I got all the connecters in place and left out the tranny ecu but he said know, youe need a manual harness. Then he printed off the sacmantics for for harnesses and showed me the differences, but I was like ok, not much of understanding when looking at some I don't understand. But later figured it out and checked all the wiring and found something in the trottle control and the CPS wasn't connecting like it was suppose to and what not. So I got a manual harness and swaped it in and started right up no problem. And I lost the papers of the wiring too which sucks because it was a great reference, but if you got access to all data then you should be able to get it.

i have found that i may have to cut a hole into my fire wall where the wires from the inside of the engine compartment to the location inside the cab where that TCU is supposed to be located. I will install the TCU but not hook it up as one day you never know i may want to install an auto..lol.

The reason i am switching harness is the last owner or one before that did a ton of crappy wiring and there is sooooo many splices and duct taped bare wires i am suprised the thing ever ran. I even found a set of 4 wires that look super glued together, they have some sort of glue rez on them. I should put pics up of what not to do when wiring...lol. i also need to eliminate the harness as a pos problem with a no spark issue. And yes i have replaced the CPS as per 5-90's instructions.

I still say get a manual harness if you can or swap a auto in now. But thats just my 2 cents, I had several hedaches dealing with my wiring, but it's your call and your rig. Good luck with it.

i will be doing a direct cps connection between the cps and the ecu aswell

conversion just about complete did find out that it will work just have to jump or mod the NSS and it should start.