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Aw-4 trans question

Newtome-craptoyou

NAXJA Forum User
Location
Portland, Or
So Saturday I picked up a 98 xj and knowing it had trans issues, the price was good enough for me to pull the trigger.

The issue is with the auto trans, it’s an aw-4, and when it is put in drive, it starts out in what feels like 3rd. And won’t go into 1st unless you physically put it in 1st on the gear selector, and then manually go through the gears as you get going.

My questions, is this a solenoid issue or a TCM issue?
How can I troubleshoot the issue to tell?

I do have a line on a rebuilt aw-4 from a friend (same year trans, made sure of that) as this one has (presuming) 270k miles on it. I just don’t want to do A tranny swap if I don’t have to.

Thanks guys.
 
If you disconnect the TCM and shift the trans 1-2-3-OD with the floor shifter, and the results seem normal, it is very likely the trans and solenoids are fine, and the TCM or some kind of wiring harness issues is the cause of the symptoms. A search on Google will find an AW-4 Service Manual.
 
Have you pulled codes yet? Any P7xx codes?


If it's starting in 4th gear with the shifter in (D) and shifts with the shifter then the likely issues are 1) the trans computer has no power (check fuses), 2) damaged wiring (check the wiring at the trans computer and where it runs down the firewall to the trans), 3) or a bad shift solenoid (measure the resistance on the wires at the trans computer).

A bad trans computer is possible, but the least likely and I've only heard of a few confirmed cases where replacing the trans computer solved the problem.
 
Have you pulled codes yet? Any P7xx codes?


If it's starting in 4th gear with the shifter in (D) and shifts with the shifter then the likely issues are 1) the trans computer has no power (check fuses), 2) damaged wiring (check the wiring at the trans computer and where it runs down the firewall to the trans), 3) or a bad shift solenoid (measure the resistance on the wires at the trans computer).

A bad trans computer is possible, but the least likely and I've only heard of a few confirmed cases where replacing the trans computer solved the problem.

Also, when my XJ did that i.e. started out in 3rd gear the shift solenoids were the culprit. You could take an ohm reading by probing the wires in the connector close to the firewall on the passenger side. In my case, the solenoid for 1 was dead and for 2 was intermittent.
 
So the XJ isn’t growing any codes at all so I don’t know about the codes at all.
Thanks for the insight as to where to look for troubleshooting. I’ll get on those as soon as I can get time off work to crawl under there.
 
This might help explain why a bad #1 solenoid causes you to start in 4th.



1st gear - Solenoid 1 is engaged
2nd gear - Both 1 and 2 solenoids are engaged
3rd gear - Solenoid 2 is engaged
4th gear - Neither solenoid is engaged
 
The same thing happened to me last week. Drove 500 miles and lost 1st, 4th, and OD on the way home.
Replaced the solenoids (global transmission kit had all 3), new fluid, filter, and gasket and full function restored. Not difficult at all.
Hope you figure it out.
 
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