• Welcome to the new NAXJA Forum! If your password does not work, please use "Forgot your password?" link on the log-in page. Please feel free to reach out to [email protected] if we can provide any assistance.

Bad Torque Converter?

techno1154

techno1154

NAXJA Member
NAXJA Member
Location
In the islands
I think mine is bad. It no loner go into lockup. A few times this week it seem to stay locked until the XJ came almost to a complete stop. Today, it do not lock at all instead remaining 300 to 400 RPM above what is/was normal for a given MP on the highway. All fuses seem to be good. I does shift thru the gears as speed increases.

Is there a way to isolate the problem without removing the transmission?
 
I would verify that the solenoid is getting a signal before going any further.
 
RCP Phx said:
I would verify that the solenoid is getting a signal before going any further.
Click to expand...

Yes, I need to do extensive tests before start pulling everything apart. Unfortunately, I am 400 miles away from home, sitting in a hotel with limited access to test equipment. I do have a Fluke VOA meter as part of my tool kit but working in a hotel parkin lot,.....

I would like to remove it at some point though. It have over 365,000 miles on the clock. I view the torque converter and pump as a semi-consumable items, but not at this time. Some time in 2003 or about 200,000 miles ago, I replaced all the sift solenoids because the first gear solenoid was bad. I have worked flawless since then.
 
If you should find out that you need a TC, I have been more than happy with my OPT one.
 
RCP Phx said:
whoops..... https://www.oregonperformancetransmission.com/product/ORE-97-3.html
Click to expand...

Thanks. I appreciate the tip. I will certainly follow up on it.

I just took the XJ out so I could get dinner. It ran well, torque converter locked up the way it should and it is back to not unlocking when it should. I will have some time this weekend to look at it a little closer.

For unknown reasons, I doubt it is an electrical issue. Why? I cannot say. Maybe it is because my XJ have a lot of miles on it. However, I will look at the PCM, TCM, TPS and speed sensor including the break light switch which also doubles as the torque converter unlock switch.
 
techno1154 said:
I think mine is bad. It no loner go into lockup. A few times this week it seem to stay locked until the XJ came almost to a complete stop. Today, it do not lock at all instead remaining 300 to 400 RPM above what is/was normal for a given MP on the highway. All fuses seem to be good. I does shift thru the gears as speed increases.

Is there a way to isolate the problem without removing the transmission?
Click to expand...

Check that the brake light switch is working, as the trans computer uses that as a signal to unlock the t/c. This is a more common problem on the older Renix Jeeps as they used a separate switch at the brake pedal that was less obvious when it was the problem. I would also measure the resistance of the t/c solenoid to see if it measures bad. Also, you can connect a meter or test lite to the wire going to the solenoid to verify whether the trans computer is trying to power it. The solenoids can be replaced by dropping the pan and filter.
 
I completed the 350 miles back home with no unusual hiccups other than the converter lockups which appears randomly but more noticeably when I try to come to a complete stop. Then it sound and feel like trying to stop a manual sift vehicle without depressing the clutch pedal. If I move the shift lever to the 1/2 position it immediately unlock and all is good.
I did also notice that when I start moving from a complete stop it will sometimes go into lockup as soon as it shift to 2nd when the lever in 3 or D. Other times it seem to remain 4OD at speed as low as 30 MP. When this happens, manual shifting or a generous application of the gas pedal will cause it to quickly select the correct gear.
 
cruiser54 said:
Have you looked at the brake pedal switch? Have you completed Tip 10?
Are your brake lights working properly?
Click to expand...

Yes, I checked the brake light switch. The lights work properly. They light every time the pedal is pressed. Sometimes the converter unlocks, other times it do not even though the lights come on.

I replaced the TPS and unplug then re-plug the TCM a few days ago. The idle is smoother, upshifts are better but it still do not unlock sometimes. This is especially noticeable when slowing down, the AW4 appear to remain in high gear. Manually down shifting it always help. Otherwise, everything else are just fine. I recorded 20 MPG goin down I-10 from Jacksonville, FL to Alabama yesterday with cruise set at 70 MP.
 
What about Tip 10?

I don't have a wiring diagram for your year at my finger tips.

But, I THINK the brake light switch may be dual function.

When it closes to operate the brake lights, it breaks the ground to the torque converter solenoid.
 
cruiser54 said:
What about Tip 10?

I don't have a wiring diagram for your year at my finger tips.

But, I THINK the brake light switch may be dual function.

When it closes to operate the brake lights, it breaks the ground to the torque converter solenoid.
Click to expand...

T/C solenoid is grounded through the trans, and gets powered directly from the TCM

I don't have a 1996 FSM, but 1995 and 1996 have the same part number for the switch so I'm going by the 1995 FSM. The stop lamp switch has separate contacts for the brake light and a contact for signalling the tcm/cruise control. So it is possible that the switch could still work the brake light but not trigger the tcm to unlock the t/c and the cruise control to release. So the next question would be, does the cruise control disengage when you tap the brakes?

Thar switch is a common culprit for no locking, but not failing to unlock while stopping. The tcm should unlock the t/c just based on speed and what gear its in, regardless of whether it thinks the brake pedal is pressed. Could be a bad solenoid that's sticking engaged?
 
Try pouring a bottle of LubeGard Red into the
transmission to test the sticking solenoid theory.

The LubeGard will add lubrication and help to unstick
things, and causes no damage. I run it in everything to
extend trans life.
 
lawsoncl said:
T/C solenoid is grounded through the trans, and gets powered directly from the TCM

I don't have a 1996 FSM, but 1995 and 1996 have the same part number for the switch so I'm going by the 1995 FSM. The stop lamp switch has separate contacts for the brake light and a contact for signalling the tcm/cruise control. So it is possible that the switch could still work the brake light but not trigger the tcm to unlock the t/c and the cruise control to release. So the next question would be, does the cruise control disengage when you tap the brakes?

Thar switch is a common culprit for no locking, but not failing to unlock while stopping. The tcm should unlock the t/c just based on speed and what gear its in, regardless of whether it thinks the brake pedal is pressed. Could be a bad solenoid that's sticking engaged?
Click to expand...

Thanks for your reply.
I do have a complete manual for the 1996 XJ. Yes, the stop lamp have two separate circuits. I could wire in a momentary switch to use when the TC do not unlock. In that way, I will know if the switch is bad.
The other thing that baffles me is the fact it sometimes do not down shift when the XJ slows to less than 20 MPH from say 65 MPH although a generous application of the gas pedal get it to down shift to the correct gear. Manually shifting it always does the trick regardless of speed. There is no telling when this will happen. It work well 70% of the time.

I cannot do anything now because I am 8 hours away from home in mid MS and will be here for a couple of weeks, with the XJ of course.
 
The assumed torque converter issue is resolved,...it appears. I pumped about 32 ounces of ATF out and added 2 ounces of MMO after which mile by mile showed less tendency to remain in lockup. Now, it is as good as it ever was. In short, the AW4 had way too much oil in it.

And now, back to an old (years ago) problem. There is a noise at the back of the engine that seem to coming from the torque converter. It is always there at idle. The speed increases with engine speed. At about 40 MPG it goes away all the way up to 80+ MPH only to return when speed drops to about 35 MPH +/- .

I do not know much about the converter in our AW4 but I suspect some of the stators or something similar is/are loose. There are no negatives in the way it performs from a standing start, shifting up and down properly yielding 18 to 20 MPG on Florida's highways. At 380,000+ miles, it may be time to replace it.
 
They are good, at least those in the torque converter. The crank shaft end will require removing the transmission.
 
You must log in or register to reply here.

Similar threads

S
Torque converter causing low rpm engine lope
Replies
2
Views
2K
lawsoncl
L
A
High pitch whine coming to a stop
Replies
5
Views
3K
chris420
chris420
S
AW4 TC Not Locking Up
Replies
6
Views
2K
sandfreestyle
S
A
Renix TPS nightmare
Replies
19
Views
3K
Saudade
Saudade
Xtreme XJ
Crank, no start even with new CPS...
Replies
13
Views
2K
Xtreme XJ
Xtreme XJ
Back
Top