89 4.0 Wiring harness question
 

I am putting back together my dash after replacing heater core and stumbling on one connector. The wire loom comes through the firewall behind the hvac box. Multiple wire connector with a 10amp fuse inline a yellow wire. Not 100% sure if it’s used. It’s been a while since I pulled the dash apart. Any guidance would be much appreciated


https://cimg2.ibsrv.net/gimg/www.che...5bae5db2e.jpeg

Connector and fuse for the transmission Control Unit for vehicles equipped with auto trans.

thank you. Going back I can’t seem the find the TCU box anywhere under the dash. Jeep was bought last year with a transmission issue. Been doing a lot of other odds and ends on it over the last year so haven’t been driven more then a couple times down the road and back. so haven’t gotten to looking into the transmission issue. Seemed to be in the wrong gear when put into drive and had to shift manually to get going. Now thinking the TCU missing all together could be the culprit? Any suggestion?

It is on passenger side up under the dash under the glove box . did you look there?

Here is a photo of the location on this other post, scroll down to see it....

https://www.cherokeeforum.com/f2/198...ifting-213823/

It is on passenger side up under the dash. did you look there? Image from other users post, not mine ( Credit to user ... 67 GMC)

That lower panel on the dash was missing when i bought the jeep. but yes i looked in that area and under the drivers side incase it was moved. Im going to guess someone got their hands on it before i bought it

You need one.

Several on ebay right now, range from about $120 to 190 in price. check ebay warranty, it should protect your purchase. I bought a jeep engine computer off ebay, one was no good, got my money back, second one was perfect. Also consider pick and pull wreckers near you. Good source for TCU and dash board lower panel. Use Row 52 website to search Pick and Pull inventory....

https://row52.com/Search/?YMMorVin=Y...se&Distance=50


It appears 1986 thru 1990 will be the models you need for the correct tcu.

You should be able to shift manually with the shifter in the meantime, just won't have 2nd or t/c lockup. While looking for a computer, 1987-1990.5 (ie Renix years with the AW4) will have a grey connector and be plug-n-play. Green or red connectors or the mounting tabs look like bat wings are for different years or models. If you have local pull-n-save type salvage yards that still have Jeeps that old, they are usually pretty cheap.

I'd have to double check if the NSS changed, but you should be able to use a 1992-1996 computer with a few minor mods. Trim the "key" on the connector so it plugs in, and change the TPS wires so the trans computer gets the same 0-5 volt signal sent to the engine computer (the older trans computers wanted 5->0 volts).

I might have a TCU.

appreciate all the feed back. I ordered one off ebay. Hopefully its good.