crashzx6r

Got a 87 xj comand trac its an auto...has no mechanical problems but one comes and goes. it wont shift out of low gear from time to time you can drive it 1000 miles or 1 mile its not picky. it wont shift out of first no matter how high rpms go...has new fluid (old fluid was clean) new filter and cooler...if you park and let it sit a while it works fine.. its completly random thats why i think its electrical problem...it does have the comfort and power switch anyone have suggestions to fix?

finneys98xj

sounds like a sensor

crashzx6r

yea a trans guy at work said he thinks it might be some control sensor under dash or something....i was hoping someone might know what sensors and where they are i could change.....maybe replace all of emif they aint 300 a piece

finneys98xj

some one will chime in and say which one.

JeepCoMJ

it's the TCU (transmission control unit) if it's an intermittant problem.

it could also be a loose connection on a solenoid in the transmission.

-Pat

crashzx6r

do you know what tht looks like and where it is i was told my trans wasnt eletronic because there was no box on the firewall above motor for trans...i dont know that for sure...i would think it is because of power /comfort switch...im curious where that unit is

crashzx6r

can someone help me with identifying what the tcu looks like and where it is....

BlackXJ

my old aw4 did that, transmission was spent completely..hopefully, that is not your case. Good Luck.

caged

tcu is attached to the lower dash trim piece on the passenger side.

i think the 87's were yellow.


there is also a fuse inline on the harness that plugs into it.

JeepCoMJ

caged, the yellow one is the cruise control computer.


the transmission IS electronically controlled. idk who told you it's not, but I suggest you NEVER ask their opinion again, because they obiously don't know what they're talking about.

the trans control unit is on the passenger side just behind the kneeboard. if you reach up inside you'll feel it. it's about 4"x6" and is grey metal with probably a white connector, and held on by two 5/16" nuts.

BuckB91XJ

Yep, Caged hit it. (TCU) Transmission Control Unit is behind the lower dash trim over on passenger side. It is a flat square thing about the size of a CD case. it has a long thin connector on it with 2 rows of wires. This thing is the brains of your AW4. Without it, the tranny will do nothing.

caged

not exactly sure if the tcu on the amc jeeps are yellow, i know the engine computer is on an 87.
i know most tcu's are grey. i have about 8 spares from 89-90 kicking around the shop. i've changed a few.
and i now the trans is electronically controlled. hence the tcu.
hope you find it.

okcjeeper

Yep a faulty TCU can cause shift issues. Although if you replace it and it still does it then it may be time for a new trany. Now it might be that it could be adjusted as well but that is something a transmission shop would be better off doing or talking to about.

crashzx6r

guess ill change it and wait a while and see if it acts up again....thanks for all the help... I hope that a faulty tcu can make it act up from time to time because i really dont wanna park it till i get 1700 bucks for trans...lol

BlueXJ

Check the local PnP to see their tranny prices. I have had three spares and never paid over $200 for any of them. All have now been sold or used by friends so I have no spare at the moment. Only ever had one spare TCU and gave $25 for it from a 89 that had cancer to bad to save. So my point is that either way you go the outlay of your funds does not need to be large to find what you want or need. Just look around when you see or hear of one being parted out.