AW4 won't upshift

I picked up a 88 XJ from a guy and he said he was having a few problems with it but the big one was tranny was not upshifting. So after a little research I stumbled upon the "AW4 Jeep Diagnosis" trouble shooting. Here are the measurements I came up with:

C3 - 5.78v
C8 - 11.17v
C9 - .79v
C10 - Off - .00v On - fluctuates between .00v -.79v
C11 - Power - 10.82v Comfort - .00v
C14 - 16.2
C15 - 16.2
C16 - 17.3
D2 - Closed - 4.53v Open(using pedal) - 1.01
D3 - .81v
D14 - 11.38v
D16 - 10.21v

all of the above measurements were taken in order down the chart, vehicle had a trickle charger on it and trans fluid level is good. The 7.5a fuse on the fuse block tested good via test light and the fuse on the yellow wire is good also. The previous owner claimed to have changed the trans filter and fluid looks to be new. The only other thing that I have noticed is that the Volt gauge on the dash reads in the low red when idling.

Two other questions that I have is what is the connector near the TCU connector? It has two wires one is yellow, the other is blue and yellow and looks to have a grey plastic piece in it instead of connecting to the other part of the connector. The second question is where is the resistor pack that is supposed to be inline with the fues on the yellow wire?

Thanks in advance for any help and hopefully I can get this figured out and get her back on the road.

Have you confirmed that the problem is not hydraulic/mechanical?

Pull the fuse on the yellow line, or unplug the TCU. Drive it shifting manually and see how it goes.

Also, have you adjusted the throttle body pressure cable?

Did you check/adjust the TPS?

I did check the kickdown/TV cable, I'm confused on the TPS part. My TPS has 2 plugs, I check the one with 4 pins but only 3 wires correct? Or the one with 3 pins and 3 wires? What are the proper voltages to get?

I've read a little on the driving while shifting manually but was unsure about something. Do I shift it from 1-2 to 3 or wait for it to be forced to make the 1-2 shift?

Double post.

First gear only in "1-2"; third gear only in "3"; overdrive only in "D"; lock in Park; not move in Neutral, and reverse in Reverse.

Disconnect the square 4-terminal connector. Key ON, check between D (ground) and A (positive) for approx. 5 volts. If you have 5 volts, reconnect the connector to the TPS. With key ON and throttle fully closed, back probe the weatherguard connector at B (positive) and D (ground), should be 4.15 volts. If it is 4.15 volts, the TPS and its adjustment are Ok. If not 4.15 volts, adjust the TPS so that it is. If you can't adjust the TPS to 4.15 volts, replace it and test/adjust again.

For back probing the weaterguard connector a couple of small paper clips with straightened legs will work nicely.

I'll check that stuff tommorow and post up the results.

boostless said:

I'll check that stuff tommorow and post up the results.

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A little cold outside tonight? Or are the bears wandering around?

Strangest thing--attended Mountain Warfare School in Ft. Greely, AK, and Arctic Survival Training in Bridgeport, CA. Go figure!

lol, it is a little cold out but that's not why I was waiting for today. It was too late last night and I needed to get up for work this morning.

Any idea where that resistor pack is at?

This just hit me, whats the voltage at the TPS for WOT?

boostless said:

Two other questions that I have is what is the connector near the TCU connector? It has two wires one is yellow, the other is blue and yellow and looks to have a grey plastic piece in it instead of connecting to the other part of the connector. The second question is where is the resistor pack that is supposed to be inline with the fues on the yellow wire?

Click to expand...

That might be the resistor. If the resistor is bad, you won't get the power/comfort setting to work. It won't prevent upshifting. Upshifting issues are usually a bad TPS or a solenoid. Much less likely is a bad TCU or perhaps a bad speed sensor in the tranny itself (never seen one of those go bad).

ok, I checked the TPS and I didn't get anything at the connector. I put ground on D and got power from battery didn't get anything, power on A and ground to batter and nothing. I double checked my fuses and didn't get anything out of a 20a fuse labeled INSTLPS I believe. I didn't change it because I didn't get anything on either side of it with my test light. I checked my volt meter by hooking it up to the battery and got 11.7v so that's working. Any ideas?

boostless said:

ok, I checked the TPS and I didn't get anything at the connector. I put ground on D and got power from battery didn't get anything, power on A and ground to batter and nothing. I double checked my fuses and didn't get anything out of a 20a fuse labeled INSTLPS I believe. I didn't change it because I didn't get anything on either side of it with my test light. I checked my volt meter by hooking it up to the battery and got 11.7v so that's working. Any ideas?

Click to expand...

No power to A you need to check for continuity between pin D1 of the ECU and A. If it is an open circuit repair the harness. If there is continuity, then check for continuity between pin D3 of the TCU and D of the TPS.

I test drove it a little bit ago with the TCU unplugged and it shifted from 1-2 to 3 and I noticed but I didn't notice anything from 3-D but that's a given as i was only going 25. It's a little bit cold to be shooting electrical problems for an extended period at -20, i might try to go to the auto skills center tommorow and see what I can diagnose.

boostless said:

I test drove it a little bit ago with the TCU unplugged and it shifted from 1-2 to 3 and I noticed but I didn't notice anything from 3-D but that's a given as i was only going 25. It's a little bit cold to be shooting electrical problems for an extended period at -20, i might try to go to the auto skills center tommorow and see what I can diagnose.

Click to expand...

Ok, keep us updated.

joe_peters said:

No power to A you need to check for continuity between pin D1 of the ECU and A. If it is an open circuit repair the harness. If there is continuity, then check for continuity between pin D3 of the TCU and D of the TPS.

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Looking at the wiring diagrams D1 is the ground to the speed sensor, is this what you meant? D3 looks like the one I need to be checking as it is the ground for the TPS, as well as others.

boostless said:

Looking at the wiring diagrams D1 is the ground to the speed sensor, is this what you meant? D3 looks like the one I need to be checking as it is the ground for the TPS, as well as others.

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Screwed the pooch. Check continuity between D1 of the TCU and A of the TPS.

this is still on the 4 pin 3 wire plug correct? if so what is the other 3 pin 3 wire plug for? The ECU?

boostless said:

this is still on the 4 pin 3 wire plug correct? if so what is the other 3 pin 3 wire plug for? The ECU?

Click to expand...

Yes. The flat connector is for the engine computer.

joe_peters said:

No power to A you need to check for continuity between pin D1 of the TCU and A. If it is an open circuit repair the harness. If there is continuity, then check for continuity between pin D3 of the TCU and D of the TPS.

Click to expand...

Both checked out good, what's next? give it to me a few steps ahead so that I can check a few things while I'm out in the cold and used to it if you could please

PM me your email address.