I've had a sudden surging in my truck from time to time, as long as I can remember. I always thought it to be fuel related, but recently noticed the only time it does it is...if I'm cruising at a constant speed, let off of the accelarator pedal, and press the brake. It won't do it until I press the brake pedal...so I'm kind-of inclined to believe it's got something to do with the TC unlocking when I tap the brakes...anyone have a clue??

nobody??? anybody??? SOMEBODY???

sounds like the tcc solinoid acting up. will it stall on you if you get down to near stopping speeds?

I'm :confused: . Are you only asking if the TC unlocks when you let off the throttle and hit the brake? If so, the answer is yes.

No, the truck has never stalled at low speeds...wait...it has stalled on the wifey a time or two at a stoplight...she complains about something every time she drives it, though...

I know that the TC unlocks when you touch the brakes...the question, I guess, is what would cause it to unlock, lock, and unlock again sometimes while pressing the brakes...it causes a definate feeling of surging, but ONLY when pressing the brakes (only sometimes....3-4 times a day)

After reading the threads on the manual TC Lockup mod that Heath did, I'm going to check the wiring...maybe there's a short to ground?? The complete engine wiring harness had nothing but bare wires inside a piece of wire loom when I had engine problems a while back...guess it's time to check the Tranny wiring too??

Alright...I've checked the wiring the best I can without pulling the tranny out of the truck, and can't find anything. Anyone know how hard it is to change the TCC Solinoid? Or any of the solinoids, for that matter? Are they internal, or do they bolt in from the outside??

All of the solinoids require rremoval of the trans pan for access to the valve body. It should be the smaller solinoid towards the front of the transmission on the passenger side.
While you have the pan down might as well service the trans (fluid/filter) and check the pan for wear material (take a picture and post if your not sure)

went through the threads and didn't see if you posted if there were any codes. code 83,39,68,69 all deal with the TCC in one way or another.

Due to the main engine wiring harness being bad (I've since stripped and re insulated all of the wires), I have a shopping list of codes that I can't clear. I've tried to clear them with the brake pedal...both holding it, and pumping it, to no avail...so I can't really say what codes are there that are valid. I'll do a search to find out how to clear the codes, and try again...I'll post my results...

Alright. I've got the codes cleared...From memory, I had thought you pump the brake pedal while the ECM is in diagnostic mode...After checking it out online, I found that you need to hold down both the Brake pedal and ACC Pedal during the diagnostic mode.

I went for a short ride around the block, and when I got back, checked the codes. The only code I got was a code 33 (EGR Related) which didn't surprise me any...there's no vacuum pump. During this ride, however, I didn't feel the sudden surging that I'm trying to get rid of. I'll run the codes once the truck does this, and post my results afterwords.

In the mean time...Thanks

ok...codes after driving, and the sudden "surging" I feel when applying the brake are 32, 33, and 72. The first 2 are EGR related, so I'm not concerned with them...but the 72, the output speed sensor, I believe...that shouldn't cause the problem, should it??

sure it would, The PCM/TCM uses speed information from these sensors to determine the following: engine is running,vehicle speed,calculate gear ratio,CALCULATE TCC SLIP,calculate turbine speed.
Check for a dirty connection, clean with electrical parts cleaner and re-grease with di-electric grease. See if this takes care of the problem before replacement.

I've already had to take apart and clean the connector with parts cleaner twice, I believe. Something about salt water!! I just don't get it...LOL. I have yet to use any di-electric grease, though...maybe this time I'll get a tube and do it right.

Anyways, I'll try this, and let you guys know how it turns out. THANKS