• The site migration is complete! Hopefully everything transferred properly from the multiple decades old software we were using before. If you notice any issues please let me know, thanks! Also, I'm still working on things like chatbox, etc so hopefully those will be working in the next week or two.

P0742 after fluid and filter change.

A

aeidian

New member
99 Pontiac grand prix gtp 3800 supercharged 160k miles.

Transmission fluid was dark reddish brown, so I did a filter and fluid change. Took about 2 gallons. It shifts rough and fluxes, and when pressing the brake when moving and then releasing, the transmission clunks. Is this thing toast?

Edit: code scan shows P0742
 
Last edited:


Re: Transmission clunk when releasing brake

burnt fluid is never good. prob time for rebuild or replace.
 
Re: Transmission clunk when releasing brake

check your fluid level first. if problem is still there take to a trans shop and get it check out.
 
Re: Transmission clunk when releasing brake

shawngtp said:
check your fluid level first. if problem is still there take to a trans shop and get it check out.
Click to expand...

The fluid was over filled and looked old, that's why I changed it out. I've filled it now since the filter change, to right at the fill mark. I'm debating on whether or not to add another quart to put it back to where it was, or maybe a transmission additive. If I'm putting the rpms to it when it shifts, its fine. If I slightly accelerate, just enough to rev up enough to get through the gears it fluxes, and jerks. If I hit the brake while driving, about 1 sec after I release, it clunks again, everytime. Could this be a torque convertor thing? Is it possible that the fluid drained out of it? I was told that a drain and filter replace wouldn't get the torque convertor fluid out, a flush would be required for that.
 
Re: Transmission clunk when releasing brake

anytime fluid is burnt... 99.9999% chance it has done damage to the internals.
 
Re: Transmission clunk when releasing brake

Other than the occasional slip under load, and a hard shift into 4th, it seemed fine. Just thought that since it was over filled and wasn't red anymore but brown, I should do a filter and fluid. Concerned I ****ed it up by doing that ><
 


Re: Transmission clunk when releasing brake

when i first got my gtp i took it to a tranny shop and had them flush and fill it. twas there when i knew i was doing a rebuild it came out almost black and when it goes from red to brown to black that means somethings cooking in the transmission and your transmission isnt going to last much longer so you can either rebuild or replace it cost me 1300 for a rebuild. might be cheaper to go scout out a wrecking yard and grab a used one and do a rebuild on it yourself then replace your old one and if your feeling confident rebuild that one and sell it
 
Last edited:
Re: Transmission clunk when releasing brake

It almost feels like something is loose. After the filter and fluid change, I replaced the clutch on the AC compressor. I had to lower both sides of the front of the cradle to get the engine low enough to access the pulley. After I was done I snugged it back up. I checked it today, and I can't tighten the bolts anymore so it seems snug. Its almost like its coming from the right side. First to second it seems to go up and down like a slingshot, at least that's what it feels like. 2nd to 3rd bogs down real low. 4th seems to hard shift. There's some vibratition when stopping when its cold. Kinda like it doesn't want to stop.
 
Re: Transmission clunk when releasing brake

Here in Southern Illinois, temps are around 40 in the day, 20ish at night. This morning when I went out to drive it, after it sat all night, it seems to shift fine. Although, when I go to stop, the car shakes violently, almost like a manual transmission does when you don't engage the clutch when stopping. It just doesn't want to stop. I thought the damn brakes were frozen at first. It finally kicks and stops fine, and the longer I drive it and when it reaches normal operating temperature that violent stop goes away, but then the weird shifting starts happening. First to second seems to shift up, then shift down, then shift back, all in the space of 2 to 3 seconds. Second to third jerks and then the motor bogs way down, like trying to drive uphill and you hit the gas and it just bogs. There's also the clunk/kick when hitting the brake and then releasing it, no matter the speed.

I've been racking my brain to the point I've giving myself a migrane trying to go over what I did, what might have caused this. The fluid was overfull, and reddish brown, so I dropped the pan and changed the filter and put 2 gallons or slightly more, along with 24oz of Lucas trans stuff in it. As I said, I lowered the cradle on the front, both sides, but it seems to be snugged back up. Other than that, I don't recall anything. It's no coincidence that this is happening right after the fluid and filter, and it was fine before. What did I **** up here? Someone on another thread said that their filter dropped out of the tube after they put it back together. Would a filter not being in that port hole cause something like this?

Trannyman, if you're out there, you seem to be the wizard when it comes to this stuff, hopefully you can shoot your two cents in here.
 
Re: Transmission clunk when releasing brake

Just used an OBD 2 scanner and found PO742 torque convertor clutch circuit stuck on.
 


Re: Transmission clunk when releasing brake

Seems non coincidental that it happened right after I did a fluid and filter.
 
Re: Transmission clunk when releasing brake

After doing some research it seems its electrical of hydraulic when it comes to failure. I'm inclined to think that when I drained the transmission, debris is making the TCC stick open. I'm debating on whether I should take it somewhere to get it actually flushed and filled, if it will push the **** out of the valve. Ideas?
 
Recorded a video of the shift sequence. Camera shakes a bit during shifts because my hand was resting on the steering wheel and the whole car shakes.

Car actually died this morning on first drive. Went to stop and it wanted to keep going, actually stalled the motor, like if you braked on a manual transmission. But didn't clutch. It didn't want to start either, just turned over and over like it wasn't getting gas. Pumping the gas while turning over finally got it to start but it ran like **** for about 30seconds until it smoothed out. Felt like the timing was off or a spun bearing. Scared the **** out of me.

http://static.photobucket.com/player.swf?file=http://vid235.photobucket.com/albums/ee273/aeidian/VID_20101128_131618.mp4
 
Last edited:
Put it up on Jack stands and took the wheels off. Ran it in drive, drivers side spins like it should, passenger side barely moved. Thought it was a stuck caliper, so I changed that out, only to have the same problem. Without the caliper on the wheel spins like it should with no resistance. As it stands now the power to the trans is coming pretty much just from the drivers side. Is it possible that something is ****ed up inside that's keeping the cv axle from spinning fluidly but still allowing the drivers side to work fine? Or is the cv axle on the passenger side just ****ed up and its not transferring power correctly? I suppose pulling the boot off to look would tell me if that knuckle is messed up. If its not the axle it has to be something right inside the passenger side, but what could it be?
 
Turn the wheel by hand, is there more resistance to gently rocking the wheel on the once side vs the other?

It's possible the diff pin is having issues/diff etc.
 


BillBoost37 said:
Turn the wheel by hand, is there more resistance to gently rocking the wheel on the once side vs the other?

It's possible the diff pin is having issues/diff etc.
Click to expand...

I'll check it out. It seemed pretty solid last night. It sure seemed like the caliper was stuck. I put a new one on and changed the rubber hose. Gonna unplug the traction control on the hub. I had the tcs turned off when I was doing this, but it might be ****ed up. I pulled the cv boot off on the trans side, the internals look ok. When its in gear and given gas it seems like the shaft that goes into the trans is spinning, because I can see the plastic housing of the cv kinda wobbling around like it wants to spin. Can the spline on the cv going into the transmisssion break and do this? Or is it more likely something in the differential is broke and causing this to only spin part of the time? With no caliper it seems to spin fine. I'll have to put the tire back on with the caliper off and see if I can stop it by hand. Any idea what size that axle nut is, in case I need to take off the cv?
 
Spider gear seems to work like its supposed to. I turn one wheel and the other goes the other direction. Seems about the same resistance. Cv axle doesn't move at all unless I hit the brake now. Pushing and releasing the brake it will spin a bit and stop, everytime I hit it, it'll spin a little and then stop. Otherwise it doesn't really move.
 
In drive, brake off, passenger side doesn't move unless helped. I can actually spin the wheel backwards if I try, so I know its ****ed. Brakes still seem really tight on that side, trying to spin it in neutral and it doesn't move very well. Driving down the road it seems ok-ish, aside from the bad shifting described earlier. I would imagine once it gets in gear and goes, the forward movement of the car forces the passenger side to spin, catching up with the drivers side. Its all related to that tcc stuck on, but its far beyond anything I can figure out. Time to park it and swap the trans, soon as I find a salvage yard that has one.
 
What you are seeing with the car in the air and one wheel turning and the other one not turning is normal for an "open" or "non-posi" differential, which is why these cars have traction control.
 
You must log in or register to reply here.
Back
Top