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Torque Converter lockup problem

Ed Kummel

NAXJA Forum User
Location
Northern VA
OK...I have a problem with my '89 Wagoneer LTD (basically an XJ).
The TQ lockup basically, well...doesn't!
I count the shifts and they stop at 4. RPMs at 55mph are almost 2.5k when it normally is under 2k.
So, my question is, where do I look for the solution? TPS? That transmission selector switch that sits on the tranny?
Any other sensors that I should be looking at?
Thanks
Ed
 
try changing the fluid, and probably the filter too. install a tranny cooler while you're at it.
 
if it were an xj, i would suggest the tps or tv cable adjustment. I'm not real familiar with the 89 pioneer, i'm working from the 96' xj view.
 
Excellent suggestions...TCC solonoid...I think there is a relay for that, right? I checked the TCM fuse and that is fine.
TV cable...hmmm, I did just replace the throttle cable, perhaps there is excessive play in the TV cable now that the throttle cable is tighter than it was.
TPS...I've always suspected the TPS but everything I've read on testing that thing was in conflict with every other thing written. I wish there was a definitive writeup on how to test this thing once and for all!
I'm a little averse to changing the fluid...the tranny is old and never serviced...this would be a last resort kind of thing..
Thanks for the info, Please...keep them coming...my weekend isnt' filled up yet!
Ed
 
My 1990 xj did this to me at one point. The next morning it wouldn't shift out of first. I ran it down to the tps. The unit was definatley junk, but different tests that I found on the sight seemed to conflict. So I went to napa and bought the damned thing. My plan was to return it if it didn't fix it. I adjusted it and the problem was solved!!!!
 
theboilermaker said:
My 1990 xj did this to me at one point. The next morning it wouldn't shift out of first. I ran it down to the tps. The unit was definatley junk, but different tests that I found on the sight seemed to conflict. So I went to napa and bought the damned thing. My plan was to return it if it didn't fix it. I adjusted it and the problem was solved!!!!

OK, my next question may be obvious...but what exactly did you do to "adjust it" properly?
Ed
 
After installing it you check the voltage with a voltmeter. depending on if you spin it clockwise or sounter clockise change the resistance and thus the voltage. I cannot remember where I found the prosedure. I will try to look it up for you tommorow, try searching for tps or tps adjustment in the mean time
 
hook up a switch from 12v power to the C14 wire on the TCU plug. when you're in 4th gear flip it and see if your convertor locks. if it does, the problem is electrical. if it doesn't, the problem is the solenoid or the convertor itself.
 
I still recommend changing the fluid. The "not changing old tranny fluid" thing is an old wives tale. Even if ther were any truth to it, it only applies to manual trannies, not automatics. You definitely should change old burnt tranny fluid.
 
I still recommend changing the fluid. The "not changing old tranny fluid" thing is an old wives tale. Even if there were any truth to it, it only applies to manual trannies, not automatics. You definitely should change old burnt tranny fluid.
The rule applies to automatics. Not manuals. I took an SAE class at ford just on this subject. Now maybe the rule only applies to Ford Transmissions? But the new fluid builds more pressure than the old stuff causing more stress. And the detergents in it can corrode seals and other items in it. Ill see if I cant find the video online somewhere and post it.
 
BrettM said:
hook up a switch from 12v power to the C14 wire on the TCU plug. when you're in 4th gear flip it and see if your convertor locks. if it does, the problem is electrical. if it doesn't, the problem is the solenoid or the convertor itself.



If the problem is indeed electrical, what suggestions might you have to start diagnosing?
 
BrettM said:
hook up a switch from 12v power to the C14 wire on the TCU plug. when you're in 4th gear flip it and see if your convertor locks. if it does, the problem is electrical. if it doesn't, the problem is the solenoid or the convertor itself.

Not to diminish the other suggestions on this thread (That tranny fluid replacement seems like it can be a whole thread in and of its self!)
but this is the kind of definite troubleshooting I'm looking for!
Thanks
I wish it were the weekend now so I can go ahead and try this!

Thanks
Ed
 
I would first check that the brake peddle switch is fully pressed in when the brakes are not applied. It also controls the torque converter, and it was moved back on my brothers comanche when the TC would'nt lock
 
I tried adjusting the brake light switch and installed a new TPS when I thought mine was acting up (TC acting funny).

Turned out I needed a tune up (plugs/wires.cap/rotor). When was the last time you did all that?
 
If you tow heavy or off hard changing you trany fluids benefits fare out way it disadvantage.
But first don't take a 10+ year old trany. Beat on it. THEN when it start slipping change the fluids/filters maybe add a cooler. Beat on the old weaken trany until it falls out on the trail. Then say "See what happen when you change you fluid"
I use to see that all the time.
If the trany was burnt bad it needs more then just a fluid change. You just wasted time and money.
If fresh trany fluid pops a seal it was well on it's way out anyway. The hard offing or heavy towing had more to do with popping an old seal then a little presser fresh fluids makes.
OK if you got a 10+ year old trany with 180k on it. DON'T change the fluid but don't beat on it alot unless you carry a bucket to put the parts in.
Just use your heads.
 
Last edited:
IH392 said:
I would first check that the brake peddle switch is fully pressed in when the brakes are not applied. It also controls the torque converter, and it was moved back on my brothers comanche when the TC would'nt lock

The NSS switch is not likely to be the problem. TPS might be bad, but I suspect you'd see other shifting issues as well.

I think the first place to start is the brake pedal sensor for the trans computer. On an 89, the torque converter switch at the brake pedal is not part of the brake light switch. Look higher up near the top of the pedal arm and you will see a white switch. It may have a vacumn line attached to it for the cruise control system as well. That is the switch that tells the trans computer when the brake pedal is depressed. I've seen more than a few of these gummed up and not working. As I recall the switch closes and grounds the sensor line when the breaks are applied, so look for 12 volts on one side to disappear when the brake is pressed.

The switch is easy to remove and clean, but may involve some contortions to get to. There is a screw behind the right side of the gold-plated bracket that you remove and slide the bracket to the right to remove. Once the bracket is out, you'll see how the switch can be popped apart. Just clean out the dried grease, clean up the contacts with some light sandpaper and reassemble with a little dielectric grease.

As a test of t/c lockup and this switch, you can get up to speed and drive normally. Then tap the brake pedal with your left foot and you should see the rpm jump up when the tc unlocks.
 
lawsoncl said:
<snip>
I think the first place to start is the brake pedal sensor for the trans computer. On an 89, the torque converter switch at the brake pedal is not part of the brake light switch. Look higher up near the top of the pedal arm and you will see a white switch. It may have a vacumn line attached to it for the cruise control system as well. That is the switch that tells the trans computer when the brake pedal is depressed. I've seen more than a few of these gummed up and not working. As I recall the switch closes and grounds the sensor line when the breaks are applied, so look for 12 volts on one side to disappear when the brake is pressed.

The switch is easy to remove and clean, but may involve some contortions to get to. There is a screw behind the right side of the gold-plated bracket that you remove and slide the bracket to the right to remove. Once the bracket is out, you'll see how the switch can be popped apart. Just clean out the dried grease, clean up the contacts with some light sandpaper and reassemble with a little dielectric grease.

As a test of t/c lockup and this switch, you can get up to speed and drive normally. Then tap the brake pedal with your left foot and you should see the rpm jump up when the tc unlocks.

OK...This is now fixed...and the above is the winning answer.
Looking under the dash, there are several switches interacting with the brake pedal. One is a multi-connection black box and then further up on the pedal, attached to a metal bar is a white box with a long plunger on it and a vacuum line. This is the switch in question.
Since screwing it in wasn't an option, I pushed the switch through it's pressure fitted spring-nuts forward to contact the brake pedal bar. Unfortunatly, this wasn't good enough. The switch plunger needs to be completly depressed to work, so I showed it my check-book balance and now it's really depressed! ;-)

So, anyway...it will only work when the plunger is completly pushed into the switch housing....
Thanks for every one's help in this!
Ed
web/gadget guru
 
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