4L80E no TCC some weird symptoms

[shovelhead90*]

I've searched for something similar to the symptoms I've encountered. My Torque converter clutch has for the most part quit working. I say for the most part, because I've discovered a crazy twist in the last couple of weeks.

First I had a run problem with the engine several weeks ago. All of a sudden the truck started running really lousy and missing and misfiring badly, and I took it to a facility that I'm familiar with and trust for diagnostics. The TCC had already quit but it's been cold and I figured to work it out when the weather improves. So when I heard it fire back up out in the shop it sounds really good. They came back and told me the distributor had been put in wrong. I replaced the distributor two years ago and it had not been back out. Until the day before Christmas it had run flawlessly.

After a couple of days the truck developed a little occasional missfire. I started trying to duplicate the malfunction and at one point shifted into neutral and then back to drive and the missfire immediately goes away for a while. It will also go away on it's own. I took it one step further and while going down a straight stretch of highway I shifted into neutral and shut the engine off. As soon as the guages all went of I restarted the engine and dropped the transmission into drive. It then went into OD and the TCC engaged for about a quarter of a mile. It was solid feeling and the engine RPM dropped 400 plus RPMs.

I'd almost decided to replace the TCC solenoid when it warmed up but now I think it may be a sensor or the ECU. I've not had any codes stored at last check, but the little scanner I used ain't the best around and shop time where I've taken it is expensive.

Anybody experienced this kinda' thoing before??

 

[skylark]

Yep. I chased my tail on it from TX to OR when we brought our truck home. First we thought shift solenoids and replaced them. Then It was the pressure switch. Next was the TCC solenoid. It turns our it was the torque converter slipping ever so slightly (more than 30 rpm) and it would kick it out of lock up and OD.

 

[shovelhead90*]

Mine stays in OD and when the clutch is applied doesn't feel like it's slipping. The TCC on the '97s is Pulse Width Modulated and supposedly never completely locks up, so I can't just put a switch on it. That would cause the TCC solenoid to fail in short order.

 

[rhino]

What kind of truck, yr model, engine size? I have seen worn distributor bushings cause this. It causes the tachometer to fluctuate enough to command LU in and out. Also the knock sensor, a misfire, or the Map sensor can cause an erratic lockup. Oh and the brake switch. They go out a lot also. Unfortunately you may have to take somewhere that can scan it and watch the data to see what sensor is causing this. We usually will diagnose something like this for around $35.00. Call around to a few transmission shops and see if they will diagnose it.

 

[shovelhead90*]

It's a '97 C3500 454 extended cab dually. The distributor is a new, (late December, 2012 install) Delphi unit as is the MAP sensor. The truck stopped going into lockup in late Nov. of last year. It's not eratic. It doesn't lock up unless I shut down the engine while coasting and then restart. It will go into lockup one time and then drop out after about a quarter to half a mile. The truck has 359,000 plus miles on it and I'm betting it's electronic in nature. I have straight dual exhaust and all new O2 sensors as well. I does run very cool, somewhere in the 160 degree range, but it's been set up like this for a number of years and the TCC has worked correctly all of that time.

Like I said, WEIRD!!

 

[rhino]

I would defiantly lean with toward electric. Usually on a 4L80E if the converter is slipping or bad it will lockup, just slip and shudder. I would start by monitoring the brake switch with a scanner and see if it is turning off and on. It wouldn't take long watching the data on a scanner to see what is the culprit.

 

[shovelhead90*]

I'll try to borrow a descent scanner next week and see what I can see.

 

[magimerlin]

Check the main harness going into the transmission... Mine was leaking on the transmission end. The large electrical plug coming out of the trans is only held in by a couple clips and is sealed by 1 o-ring. The whole internal harness and that plug are one piece but easy to change out, if it's leaking fluid there. It caused my to not get the right signals.

Not sure on a 97 but on my 94 4L80E there are two vss. One ore both of those could be bad as well.


Sent from what use to be a great country.