When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Stock XJ Cherokee Tech. All XJ Non-modified/stock questions go hereXJ (84-01)
All OEM related XJ specific tech. Examples, no start, general maintenance or anything that's stock.
Trans will not down shift, start engine put in gear an it's in 3OD not 1st, shift to 1st an it's in 1st. Will shift all gears manually. Checked TPS, Changed trans controller. Reset kick down cable, still has problem.
Likely the fuse to the Trans Control Unit is blown. You should go ahead and do the Tip below before anything else. How did you check the TPS? CRUISER'S MOSTLY RENIX TIPS
Over near the transmission dipstick tube are 2 rather large connectors. One is black and goes to the NSS and the gray connector goes to the transmission itself
. These 2 connectors carry all the info between TPS, TCU, NSS, speed sensor, and transmission solenoids.
Unplug each one, visually inspect for corrosion or bent pins, spray them out with electrical contact cleaner and plug them back in.
Additionally, if your Jeep is an ’87 to ’90 Renix, it’s always a good idea to reach up under the glovebox area and unplug the connector to the TCU and spray it out along with the receptacle of the TCU. While you’re there, find the fuse right in that area for the TCU. Remove it and spray out it’s receptacle and clean any corrosion from the fuse.
Changed TCU, fuse is 25 amp not sure if it's right size. Trans will shift 1st, 2nd, an 3rd automatically, run up to 70 mph no shift to OD. 2800 rpm at 65 mph. Idles at 800 rpm. What is the yellow box on driver side under dash?
The stock fuse in the harness by the TCU is a 10-amp (red). Being an 89, if it's not locking up the torque converter (which some refer to as OD), check the trans/cruise switch at the brake pedal. It's not the switch for the brake lights. The switch you're looking for is white and higher up. It will also have a vacuum line to it it you have cruise control. This is the switch that tells the trans computer to unlock the t/c when you hit the brakes. If it's out of alignment or got knocked loose, the trans computer won't engage the torque converter lockup, thinking you have your foot on the brake. You may also have problems getting the cruise control to engage.
If you think it's shifting at inappropriate speeds (ie acting like you've got it floored), I would test the TPS sensor. It never hurts to adjust the throttlebody to trans cable too. BleepinJeep has a great youtube video on it. If you're still having issues, I would measure the resistance of the solenoids with a meter at the TCU connector. Neither shift solenoid is engaged for 4th, but if you're still not getting lockup then the t/c lockup solenoid could be bad.
I think the yellow box on the drivers side is the cruise control module. Don't mess with the settings on it.
That's black. Yellow would be the cruise module. Sometimes people get tempted to muck with the adjustment screw when cruise isn't working. That just makes it worse because the problem is almost always a vacuum problem or that switch I just mentioned.
Just spent a ton of time testing everything your testing, yup TPS spec'd out fine too. Gave up and fired the parts cannon at new oem mopar TPS. Done, shifting fine again. Past bad TPS's have had different shift problem, super late up shifts. This time no downshift felt, no kickdown at any speed, fast upshift like 4th gear by 15mph. Manual shifting was fine with tcm unplugged but no downshift. They say an old analog meter can see bad TPS but it seemed to be steady swing when I tested, and the red brick wont tell you anything but the value percentage its set at, handy for setting it though.
NOS OEM TPS can be had on Ebay for $30. I picked up 2 at that price.
AUGUST 6, 2016CRUISER5442 COMMENTSEDITEven though the indicator lights up in your Power/Comfort switch, that does not mean the switch is working and putting the Transmission Control Unit into Power mode.
The switches had a high failure rate.
Remove and unplug the switch. In the harness are 3 wires. One has a stripe, one is tan, and the other wire is black.
Make a 4″ jumper wire with a male spade at each end.
Plug one end of the jumper wire in the cavity for the tan wire and the other in the cavity for the striped wire of the harness and you’ll be in permanent Power mode.
Stuff the harness back in and reinstall the switch for looks if you want.
Make sure the 7.5 amp “Trans” fuse in the fusebox is good.
If you happen to have a 91 or 92 XJ/MJ and it has the Power/Comfort switch, just jumper the Tan and Blue wires in the harness plug.
That's black. Yellow would be the cruise module. Sometimes people get tempted to muck with the adjustment screw when cruise isn't working. That just makes it worse because the problem is almost always a vacuum problem or that switch I just mentioned.
Finally stuck my head under the dash. Yep, Yellow = CC Module. Thanks!!
08-03-2021, 06:55 PM
1989 Jeep Wagoneer
