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View Full Version : Possible TCC issue with 4l60e transmission. Help needed.



AndyB
12-04-2006, 03:06 PM
The transmission in my truck is starting to surge/buck in high gear under a light load. So far I cannot make it happen, but it is starting to occur more and more often. The one constant I found is that it does it most often (but not always) when it is cold or has sat for a few days.

History on the truck, 98 s-10 4.3 I have owned since new. Two years ago at 165k the friction material for second gear let go, so I rebuilt it at that time. I replaced all the seals, bushings, friction materials, torque converter and the entire valve body. The truck now has 210k on it, I stopped using it as my daily driver (75 miles a day) back in June and this problem has started since then.

I have attached some screen shots of data that I captured while the trans was acting up, but I am no mechanic so I知 not sure what the data is telling me.

If anyone has any ideas, please post em up before I start doing the only thing I know to do, and that is to start throwing parts at it!

The captures are about 150 frames long and you can see about 45~50 frames in each one of the pictures. I can move forward or backwards through each capture, so if anyone wants to see another part of the sequence let me know.

Thanks,
Andy

myclone
12-05-2006, 08:23 AM
Im no expert on OBDII stuff but I do mess with transmissions on a regular basis so I'll throw my .02 out there under the assumption that youve checked for the obvious like bad gas, water in the gas, old/stopped up fuel filter, varmits chewing up ign or electrical stuff under the hood, etc (dont laugh at the varmit comment...Ive seen it happen to vehicles that sit for extended periods and Ive pulled my hair out more than once trying to track down the problem only to find a critter had made dinner out of the wiring harness or plug wires).

1. How old are the ignition components...originals? Have you gotten any random misfire trouble codes? If yes to either of those then by all means do a tune up (plugs, wires, etc) since the delco stuff is done for in my experience by, at most, 100k miles. Reason Im mentioning ignition is at low speed in 4th gear and moderate throttle cyl pressure is fairly high and you could be experiencing spark blow out. Ive seen the same prob with lower milage (or even new) el cheapo chain store ignition components that were installed too.

2. When you rebuilt the trans did you install all new electricals too? On any 60E or 80E with over ~100k that I rebuild it gets all new selonoids and gear select switch just to be on the safe side. In doing this Ive prolly replaced more than one electrical component that was working fine but its cheap insurance IMO since those pieces can fail from wear and tear just like anything else and the trans comes back (and I look like an idiot to the customer).

3. Considering your milage have you ever replaced the TPS or have you ever gotten any TPS codes? Ive seen on OBDI stuff where the TPS is worn or has a bad/dead spot just above idle where the internal wiper of the TPS spends 95% of its time which can cause drivability issues when the TPS wiper hits the bad spot. Use an analog meter (digital wont catch it) to read the resistance of the TPS as you slowly actuate the throttle with your hand. The needle on the meter should move in a smooth manner as you open and close the throttle slowly but if you hit a spot in the TPS where the needle on the meter jumps around then settles back down youve got a worn TPS. A bad/worn TPS could be causing your symptoms...Ive seen it before on OBDI stuff and not a single code was stored so it might be worth checking even though your truck is OBDII.

4. When the truck starts acting up lightly step on the brakes. Just enough pedal to turn the brake lights on but not enough to actually apply the braking system. This should actuate the TCC switch and unlock the TCC. Does the bucking stop and the trucks drivability smooth out when you do this? If so Id bet that the TCC selonoid is sticky or on its way out..its easy to change (two bolts) but you have to pull the pan on the trans to do it.

Thats all I can think of right off but if none of the above pan out try adding a bottle of red Lube Guard. This is the only addative Ive ever found that isnt some kind of snake oil. My daily driver with the same trans as yours was rebuilt by me but at ~25k miles developed a late 2nd to 1st down shift as I would slowly come to a stop. Rather than pull the trans again another trans builder suggested that I throw a bottle of the red lube gaurd in it and its been doing fine ever since. While IMO thats not the right "fix" it sure beats working in a cold garage pulling the trans out of the beater truck.

AndyB
12-05-2006, 02:46 PM
myclone, thanks for the ideas.

Yes, when the trans is acting up I can either tap the brake pedal and it will stop, or I can mash the gas and it will down shift and stop. This is why I think it has something to do with the lockup converter.

The truck has no stored codes or lights on the dash, but the tps is something I had not thought of. I cannot remember if the valve body I installed when I did the rebuild came with new wiring or not. Something tells me that it did not, but I do know it came with a new tcc solenoid, because I remember comparing the old one to the new one while it was on the bench.

Every piece of the ignition system has been replaced at least once, it is currently on it痴 third set of spark plugs (including the originals). All parts are from the GM dealer. The last time I changed plugs approx. 50k ago, I tore one of the boots while taking it off the plug. The next day as I began to climb a small hill it started missing/stumbling, I knew right away what it probably was and a new set of wires fixed it. The plus side to that incident is that I now know what a misfire type shudder feels like, and this current problem is not the same.

The point about an animal chewing on the harness is a good one and that is something I am going to take a good look at before spending any money. However I still drive the truck at least once a week, so it has not been sitting idle for months and months.

The tcc solenoid was the first thing I was planning to try, but I guess I should try an additive/flush first. What could it hurt?

I spoke with my GM parts guy today and he says they sell a lot of pressure control solenoids. My cost is $65 for that piece, or $30 for the tcc solenoid. If the additive/flush does not work, I値l have a look at the tps, if that does not help then I guess I値l start replacing solenoids.

Thanks again,
Andy

myclone
12-05-2006, 05:50 PM
myclone, thanks for the ideas.

Yes, when the trans is acting up I can either tap the brake pedal and it will stop, or I can mash the gas and it will down shift and stop. This is why I think it has something to do with the lockup converter.

The above makes sense because the TCC unlocks when you apply the brakes or accellerate moderately. The factory trans will lock the TCC in 2nd, 3rd, and 4th but any kind of hiccup will show up the worst in 4th since the engine has so little leverage on the weight of the vehicle due to gearing.


The truck has no stored codes or lights on the dash, but the tps is something I had not thought of.
The OBD-II PCM like you have is pretty smart compared to the old OBD-I stuff that I usually mess with. An educated guess is that if the problem was even remotely more than instantanious the PCM would kick the SES light on the dash board. Id still check the TPS though before I pulled the pan since you'll stand little chance of getting trans fluid in your hair/face checking the TPS LOL.


I cannot remember if the valve body I installed when I did the rebuild came with new wiring or not. Something tells me that it did not, but I do know it came with a new tcc solenoid, because I remember comparing the old one to the new one while it was on the bench.

Ive never seen a VB or rebuild kit come with a harness and to be honest with you Ive never had to replace a 60E harness yet. Some early 80Es had a crappy internal harness but the 60Es seem to be fine on all the units Ive dealt with. The only thing I can think of right off is the possibility that the harness got pinched between the filter and VB when the pan was tightened and over time vibration chewed the insulation up and its just now shorting the harness to ground through the VB. Thats a stretch IMO but stranger things have happened.


Every piece of the ignition system has been replaced at least once, it is currently on it’s third set of spark plugs (including the originals). All parts are from the GM dealer.

Good man...for stock ignition set ups the Delco stuff is hard to beat and all my personal vehicles get nothing but Delco ignition components when its time for them. Delco has never let me down/stranded me in BFE....yet.


The point about an animal chewing on the harness is a good one and that is something I am going to take a good look at before spending any money. However I still drive the truck at least once a week, so it has not been sitting idle for months and months.

Ive seen mice or chip monks do some damage over the course of just a couple days so dont rule it out completely especially if you live in a suburban or rural area. I live out in the boonies so critters can be a problem and Ive cussed them more than once is why I mentioned it.


The tcc solenoid was the first thing I was planning to try, but I guess I should try an additive/flush first. What could it hurt?

The red Lube Gaurd wont hurt anything and in my case cured a minorly annoying issue with my trans. Id try it and see what happened since its easy and cheap. If the Lube Gaurd works then you know the problem more than likely isnt an electrical issue and you'll need to eventually go back into the trans to some extent (or just add the Lube Gaurd when you change the fluid/filter every time).


I spoke with my GM parts guy today and he says they sell a lot of pressure control solenoids. My cost is $65 for that piece, or $30 for the tcc solenoid. If the additive/flush does not work, I’ll have a look at the tps, if that does not help then I guess I’ll start replacing solenoids.

If the Lube Gaurd, TPS check, and no pinched wires under the filter dont pan out I would personally swap in a new TCC apply solenoid first. If the press control solenoid was acting up the trans would go to max line pressure and all the shifts as well as TCC apply would be REALLY harsh. From the sounds of your symptoms that doesnt appear to be the case and its just the TCC apply is what is causing your problems which as you know has its own solenoid. Not to mention its the cheaper of the two which is always better when youre to the point of just throwing parts at a vehicle to trouble shoot it...BTDT.

Hope this helps you some or at least steers you in the right direction to find the problem.

Dave

AndyB
12-06-2006, 02:56 PM
Thanks again Dave, very sound advice.

From what I can tell, it seems to be getting worse, I took it for a trip to home depot last night and it was jumping in and out of lockup at any sort of load, even on flat surfaces.

I am going to start looking at it this weekend. My gm parts guy is good about letting me return stuff so I知 going to go ahead and pick up the solenoids just in case the other things you mentioned do not appear to be causing the problem.

I値l post up what I find.

Andy

RatMalibu
12-06-2006, 08:35 PM
my 94 full size developed a similar surge/buck with the TCC applied.....mine ended up being a bad plug wire (AC Delco from the dealership I work for and only 6 months old) there was a hole that looked like someone had stuck a large needle through the jacket where it was arcing to the spark plug heat shield....another new set of wires and the problem was gone....almost enough to make you pull your hair out isn't it??

AndyB
12-08-2006, 12:26 PM
Great diagnosis Dave! It was the tps sensor.

While driving it to work today the check engine light came on, the code was P0101mass airflow sensor performance. I also noticed that at 75~80 mph on the freeway, the torque converter acted just fine. I could tap the brake and the torque converter would quickly and cleanly unlock, then lock right back up a few seconds later. But when I took an exit ramp at 45-mph or so at light throttle, it would lock and unlock back and forth like crazy.

So instead of picking up the transmission solenoids from the dealer I picked up a tps sensor for $30. As soon as I took the old one off, I was pretty sure that the sensor was the problem. The black plastic piece that rotates on the throttle shaft was very loose and if you shook it, you could hear it rattling around inside the housing. I put the new one on in the parking lot and I’ve driven the truck about 50 miles since with no incidents at all.

Thanks again Dave, you saved me some real time and money.

Andy

myclone
12-08-2006, 01:05 PM
Great diagnosis Dave! It was the tps sensor.

While driving it to work today the check engine light came on, the code was P0101mass airflow sensor performance. I also noticed that at 75~80 mph on the freeway, the torque converter acted just fine. I could tap the brake and the torque converter would quickly and cleanly unlock, then lock right back up a few seconds later. But when I took an exit ramp at 45-mph or so at light throttle, it would lock and unlock back and forth like crazy.

So instead of picking up the transmission solenoids from the dealer I picked up a tps sensor for $30. As soon as I took the old one off, I was pretty sure that the sensor was the problem. The black plastic piece that rotates on the throttle shaft was very loose and if you shook it, you could hear it rattling around inside the housing. I put the new one on in the parking lot and I致e driven the truck about 50 miles since with no incidents at all.

Thanks again Dave, you saved me some real time and money.

Andy

Andy,

Glad I could help you and be aware that your accurate symptom descreption as well as paying close attention to what the truck was doing when acting up helped a tremendous amount (pat yourself on the back too LOL).

What is suprising to me is that the ECM kicked a code for the MAF before rather than a TPS. While I can see how that would happen I would have figured the OBD-II ECM would have picked up on the flakey TPS first. Maybe the MAF takes precedence over the TPS in the higherarchy of the ECM....thats something a GM power train engineer would have to answer though.

None the less congrats on getting the daily driver back to good health.

Dave