I was tearing apart my dash , and on the passenger side under the dash, there is a box with a wiring harness, which I had to disconnect for a bit. When I drove the vehicle, it seemed like the power was lacking, and it took more RPMS to start moving. As soon as I reconnected the device, it drove normal. Is this a part of the transmission, or something to do with the engine. It is a gray box, about as big as a CB radio. I have a 1988 Wagoneer. Any ideas, folks?
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- Thread starter keith
- Start date
Bounty__Hunter
Super Moderator
Is it the XJ Wagoneer similar to a downsized Cherokee? Then it could be the TCU (transmission control unit). If you have the SJ Wagoneer (full-size Jeep) I'm not sure what it is.
yes, its the regular wagoneer, not the grand. Thanks. I was just wondering. Hell these jeeps got a lot of crazy stuff.
Bounty__Hunter
Super Moderator
The Cherokee and Comanche area about the only ones that use that TCU to control the transmission. Isn't Wagoneer your trim level and the model is actually a Cherokee?
FloridaCherokee1988
New member
Not sure about under the dash but I know on an 88 XJ on the passenger side under the dash behind the plastic kick panel is the ECM, bout as big as a CB radio with a wiring harness running into it. However, I wouldn't expect the engine to start at all if you disconnected it.
Well, it has the double headlights. Just a plain old wagoneer, which I love dearly. lol. It only has around 170K on it. Just getting broken in, lol.
FloridaCherokee1988
New member
Hell ya man 170k aint nothin on a 4 liter if its been taken decent care of.
MoparMatt77
New member
Bounty hunter is correct. Passenger side shiny box size of small CB attached to lower dash cover... That is a TCM (Transmission control module).
Unplug and drive in reg "D" it will be hella slugish cause Jeep is only driving in 3-4th gear. Unplugged you'll still be able to drive it like a manual automatic; from 1-2-3-4/D.
The PCM/ECM on 87-90XJ is located under driver side dash next to lower AC vent / HVAC.
1987-1993 XJ/MJ was Cherokee, Wagoneer - downsized, Comanche. FSJ - SJ used chrysler 727 auto trans.
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