I have a 1990 Cherokee with a 4.0 and auto trans . The lock up torque converter is not locking up . We have 2 1990 XJs both are the same one runs about 1800 rpm at 65 mph when torque converter is locked and you can feel it lock up . The other runs about 21-2200 rpm at 65 mph same tires and gears . Tried swaping tps no luck . Thanks for any help.
Kenny

I've got 30's and at 65mph my tach is at 21-2200rpm's.is the mileage the same on both?couls be engine wear, maybe on's tach is off. Ihave to bump mine down 300 or so rpms by smackin' the top panel till it reads right. maybe there's a way to fix

I searched around here on this forum and didn't come up with much. So, the below quote is from naxja.org at this address:
http://www.naxja.org/forum/showthread.php?t=103675&highlight=torque+converter
The quote's on the 2nd page...



Re: Torque Converter lockup problem
Quote:
Originally Posted by lawsoncl

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
http://www.naxja.org/forum/images/buttons/quote.gif (http://www.naxja.org/forum/newreply.php?do=newreply&p=243316350)

:grinyes: :grinyes: :grinyes: Thank you :grinyes: You are the Man . That was it it was not even touching . Thank you