AW4 will not shift

I have a 1992 XJ w/ 4.0 and AW4 I bought for $400 when I bought it the tranny shifted fine it has set for a couple months now and when I got in it today to pull it in the sharp to start working on it I drove it down the street just to let it get up to temp for a while and the tranny will not shift out of first. I don't know jack about auto's and am not real sure as to where to start checking any help would be greatly appreciated.

how high are you letting it rev?

If the TPS is bad it will shift, but only at almost redline rpms.

I might of got it up to 3000 rpm. What does the TPS affect that causes it to not shift out. Also if the TPS was bad wouldn't there be some other symptoms.

idle can be a bit weird/high. But the TPS tells the computer that you are inputting throttle, how much throttle determines shift points of the electroncially controlled AW4. i.e. you stomp the gas and it downshifts and holds gear till almost redline before shifting, or you gently accelerate and it shifts smoothly around 2200 rpm.

The TPS (Throttle Position Sensor) is actually two sensors in one, there are two connectors on it, one goes the the engine brain, the other to the tranny brain.

The tranny brain side of the TPS has probably failed....

The solution is to replace it.....

If the Engine brain side fails, you will have sputtering, stalling, piss poor fuel mileage, just to name a few...

Do a search for TPS and see what comes up....

Will it hurt anything if I don't replaced it for a while? This is a trail only rig so I don't really care if it shifts out of first most of the time.

poorboy_616 said:

The TPS (Throttle Position Sensor) is actually two sensors in one, there are two connectors on it, one goes the the engine brain, the other to the tranny brain.

Click to expand...

This is only true for the for the Renix jeeps. The 91+ HO engines have a single output TPS sensor, and the TCU gets a copy of the signal from the ECM.

Incidentally, on the dual output TPS sensor, the outputs ran opposite of each other. The ECM output ran 0->5 volts, and the TCU output ran 5->0 volts. With the switch to the single output, the TCU changed to expect the 0->5 volt signal.