88jx

I put in a new brake booster and master cylinder the other day and ever since then it seems like my torque converter is always on because it has more power down low and when i apply the brakes the rpms stay exactly the same. Anybody know what to do i know i blew the fuse on the brake lights when hooking up the brake pedal does the torque converter have a fuse i could have blown? it still drives fine and everything else works on it

Outlaw Star

Uh, TCs don't have a fuse but the TCU (trans computer) does. There's one in the fuse panel @7.5A and a 10A one under the passenger side dash. The TCU controls the shift solenoids. And yes, the brake light switch also controls lock up of the converter so might want to test that too. Good luck.

caged

it could be your tcc solenoid

Outlaw Star

^one of the afore mentioned solenoids. The TCC (Torque Converter Clutch) solenoid locks the TC to the flexplate. If not disengaging, its like you're stuck in direct drive.

rrich

If the lock-up converter stayed locked, it woul be like never pushing the clutch down. It wouldn't start, if it did it would stall instead of idle.

Radi

You mean at idle- you apply the brakes and the RPM's don't change? That's normal...did your old brake booster have a vacuum leak?

rrich

It seems like he got used to the way it worked with the defective booster. Now that it does like it should he misses it.

Maybe put the old defective booster back in?

88jx

so ive tried a few things and it still seems as if the torque converter is always on. the old booster didnt have a vacuum leak that i knew of, i just did the wj swap. I searched around and on another forum it said to check if your traveling at a steady speed and then apply the brakes the rpms should go up(when the torque converter comes on). Ever since the new booster swap the rpms have always been higher and it doesnt coast as well.

88jx

where is the 10A fuse under the passenger side dash? i looked and didnt see it, mine is a renix if that makes a different

Outlaw Star

How is the check valve on the booster?

5-90

The torque converter is a hydraulic coupling between the engine and transmission, it doesn't have an "on" or an "off."

The torque converter clutch (to lock up the TC and prevent slip during steady-state cruise, reducing transmission heat generation) is electronically-actuated by a solenoid in the valve body, but if it were constantly locked you wouldn't be able to stop without stalling the engine.

(@Outlaw - the TCC doesn't necessarily lock the TC to the flexplate - it's already fixed to it with four good-sized screws. However, the TCC locks up the internals of the TC, which is what turns it from a fluid coupling to a mechanical coupling.)

Chew on your symptoms and see if you can't get a better description, because I'm not sure what the problem is. Yes, there is a small torque multiplication going on in an unlocked TC - but changing your brakes should not have had any noticeable effect on that (it's an unrelated system.)

Outlaw Star

Thanks, you explained it better than I could. (Not to mention I was in a rush. Lol)
As for the booster effecting RPMs, the only thing I can think of without a better description is a defective booster or check valve.

rrich

He's in a tither about it acting NORMAL!

duh!

5-90

Looked like you were in a hurry. Besides, "A Ranger is a teacher first" (hammered into me at Ft. Benning...) and I figured someone around here could use a lesson/better explanation. Just tryin' to help!

Outlaw Star

No worries.