Transmission Not Shifting Past First Gear

[CBJeeper]

Well, it seems I got ahead of myself on the transmission issue. Again , 1990 Wagoneer Limited 4.0 auto. Yesterday, after initially driving this new XJ, the transmission would not shift past first gear. I cleaned the TCU connectors at the firewall, cleaned up the engine ground near the dipstick, cleaned the TCU fuse in the cabin, and cleaned the TCU connector in the cabin. Test drove and shifting fine.

Today I pulled out of the drive to go get a smog check and again, will not shift past first gear. I am going to go test my TPS now. If it tests correctly, where do I turn next?

 

[lawsoncl]

Measuring the solenoids resistance would be my next step, suspecting a bad #2 solenoid. I would also inspect the wiring down to the transmission for damage, including the wire that runs to the rear for the output speed sensor. Crank the shifter back and forth a few times as it could be a dirty NSS. It's starting in park and reverse lights working?

On the 1990, the speed sensor is a magnetic relay switch that closes once per revolution (98+ is a different sensor that generates 4 a/c spikes per revolution). With the output shaft turning, you should see it changing. Either the resistance flipping between zero and infinite like a switch if measuring unplugged. Or if measuring plugged-in with power on, flipping between 0 and battery voltage. You can stick the xfer case in neutral and the trans in gear and backprobe the sensor wire right at the TCU. You'll get some rotation of the output even in neutral like this. It'll look like a/c voltage on the meter with the shaft spinning that fast. (Turn the engine off before shifting things back or it'll grind going into park)

 

[CBJeeper]

Well, after additional diagnostics, I realized that the negative battery cable termination at the battery post was needing a good cleaning/copper brightening. I did this and everything has been working properly. Passed smog for my vehicle transfer and now on to my rehab. Seat repair, headliner replacement, lift and front end rebuild, and new tires.

 

[Bent]

For posterity, the TPS will also cause the issues you are having. Been there done that. I had now have spare TCUs.

 

[cruiser54]

Well, after additional diagnostics, I realized that the negative battery cable termination at the battery post was needing a good cleaning/copper brightening. I did this and everything has been working properly. Passed smog for my vehicle transfer and now on to my rehab. Seat repair, headliner replacement, lift and front end rebuild, and new tires.

Good reason to ADD grounds per Tip 1 at www.cruiser54.com