88xj tranny problem

Yea IIRC there is a fuse for the computer. Check that like said. If all fuses and TPS check ok then I'd look at the computer.
 
I replaced the heater core and after I put it back together it stopped shifting. It wants to start in overdrive but works fine when I manually shift it. I checked fuses and made sure tranny computer is plugged in. It has a comfort/power switch and the light is not on. Is there any other wires for the tranny under the dash? What am I missing?
 
Please help! I tested tps, nss, solenoids and I have no clue where to go from here. I am beating my brains out trying to figure out what it could be. Does anybody have wiring schematics for tcu?
 
I know you said you checked the fuses...was that just the standard fuses or underhood fuses? There is a TCU fuse under the passenger side dash somewhere between the TCU and shifter. It really sounds like the TCU isn't coming into play here. Does it behave the same with the computer unplugged?
 
RenegadeT said:
I know you said you checked the fuses...was that just the standard fuses or underhood fuses? There is a TCU fuse under the passenger side dash somewhere between the TCU and shifter. It really sounds like the TCU isn't coming into play here. Does it behave the same with the computer unplugged?
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Agreed! Especially if it acts the same unplugged.
 
Time to break out a meter or test light and make sure there's actually power there. If not, trace it backwards until you find the problem.
 
RenegadeT said:
I know you said you checked the fuses...was that just the standard fuses or underhood fuses? There is a TCU fuse under the passenger side dash somewhere between the TCU and shifter. It really sounds like the TCU isn't coming into play here. Does it behave the same with the computer unplugged?
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not exactly sure what you mean by not coming into play. I have read a little bit about the wiring, there is two verified 12v power sources at the tcu. Where can I get the schematics for the tranny? TPS is set properly, IM READY TO BURN IT! Thank you guys for the help.
 
eXJunkie said:
not exactly sure what you mean by not coming into play. I have read a little bit about the wiring, there is two verified 12v power sources at the tcu. Where can I get the schematics for the tranny? TPS is set properly, IM READY TO BURN IT! Thank you guys for the help.
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it just sounds to me like the TCU isn't doing its job somehow, could be wiring issue, internal TCU, dunno. If disconnecting the TCU doesn't change anything, there's something wrong.
 
eXJunkie said:
not exactly sure what you mean by not coming into play. I have read a little bit about the wiring, there is two verified 12v power sources at the tcu. Where can I get the schematics for the tranny? TPS is set properly, IM READY TO BURN IT! Thank you guys for the help.
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The best XJ minds are on NAXJA. If its happened to an xj they have it in their forums. I have the info on 94's and 97 ups. Not sure if it applies though. I have a paper FSM at my shop/office that problaby has what you want but with the weather here idk when I can get to it.
 
eXJunkie said:
How do I test the speed sensor and the selinoids?
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I think if you can shift if manually the selinoids are working. I'm not sure if yours is the same but my 94 takes it speed sensing data from a separate speed sensor on rear of the tranny not the one on the trasfercase.
 
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eXJunkie said:
Thanks for your help. Still plugging away at the problem.
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Sure. I've not had issues like this before so my experience is limited. Anyone I have heard of having shifting issues were related to the computer.
 
I had a similar problem with my 88xj that frustrated me so bad I took all the aw4 stuff out and put a ax15 in it. Only thing holding me up on it is the double elbow rod that goes from pivot assy to transfer case... had no idea the two were different lengths. Like yours mine would start in od. Shifting manually from 1st- drive it would skip 2nd. From drive to overdrive was as if the torque converter just locked up w/o actually shifting into o/d
 
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