WhatTheFehl Posted January 9, 2011 Report Share Posted January 9, 2011 Just as the title says. I'm sure the question has been asked before, but I couldn't find anything through the search feature. The issue is that sometimes the torque converter in my car locks up perfectly and functions just fine, then other times it doesn't lock up at all. Pulling up on the brake pedal doesn't have any effect. The transmission shifts perfectly otherwise. What could be the issue here? A failed sensor somewhere? I'm not sure. It's a 1995 Grand Prix 4T60E Quote Link to comment Share on other sites More sharing options...
slick Posted January 9, 2011 Report Share Posted January 9, 2011 Whats the engine temperature when it does and does not? Quote Link to comment Share on other sites More sharing options...
WhatTheFehl Posted January 10, 2011 Author Report Share Posted January 10, 2011 I've never noticed any sort of pattern with engine temperature or anything to be completely honest. Quote Link to comment Share on other sites More sharing options...
AL Posted January 10, 2011 Report Share Posted January 10, 2011 When I drove this car it was after we had been driving around for a good portion of the night and it was at operating temp and it still wouldn't lock up on the highway Quote Link to comment Share on other sites More sharing options...
WhatTheFehl Posted January 10, 2011 Author Report Share Posted January 10, 2011 When I drove this car it was after we had been driving around for a good portion of the night and it was at operating temp and it still wouldn't lock up on the highway Yes, but Friday night driving home from work it locked up perfectly on the highway the whole way. Quote Link to comment Share on other sites More sharing options...
AL Posted January 10, 2011 Report Share Posted January 10, 2011 I was just answering slicks question Quote Link to comment Share on other sites More sharing options...
WhatTheFehl Posted January 10, 2011 Author Report Share Posted January 10, 2011 I know, but I was reinforcing the randomness of the situation Quote Link to comment Share on other sites More sharing options...
Galaxie500XL Posted January 10, 2011 Report Share Posted January 10, 2011 My '95 LQ1 Cutlass does the same thing once the trans temp rises above 180 degrees. Seems to be a common problem with the 4T60E, I believe it's related to either the PWM solenoid, or the TCC clutch solenoid, which are inside the transmission. A poster a few months ago reported success with cutting the lead at the transmission wires for the PWM solenoid, but myself, I'm planning a rebuild for the transmission before warm weather arrives. Quote Link to comment Share on other sites More sharing options...
Brian P Posted January 10, 2011 Report Share Posted January 10, 2011 The PWM solenoid should not be confused with the TCC apply/release solenoid. The PWM in simplest terms acts as a fluid pressure (or flow) regulator to the torque converter clutch to soften the application of the TCC. The PWM solenoid has a very high failure rate during its early years of introduction in the W-line (1994-1997 or so). They tend to act up and cause slipping or lack of clutch activity when the transmission has been warm for a period of driving and eventually will fail altogether. The PCM controls the ground circuit to this solenoid via "pulsations". You could try cutting the control wire, or if you want to be neat about it, pull the terminal out of the plug. This wire is located in pinout "C" of the transmission harness connector just above the vacuum modulator (under the airbox, front of tranny). The wire is "dark brown". It's worth a shot if nothing else. With the PWM solenoid out of the equation, the application of the torque converter clutch will be abrupt but it should be consistent. Quote Link to comment Share on other sites More sharing options...
Galaxie500XL Posted January 10, 2011 Report Share Posted January 10, 2011 True, but a bad PWM solenoid can lead to the symptom. The PCM monitors "slip" from the torque converter. If the PWM is too slow in allowing full hydraulic pressure for lockup (I think 3-5 seconds), the PCM will detect the excess slip, and disable further lockup attempts until the next start cycle. Quote Link to comment Share on other sites More sharing options...
WhatTheFehl Posted January 10, 2011 Author Report Share Posted January 10, 2011 PWM = Pulse Width Modulation Solenoid? (ACDELCO Part # 2141861 on RockAuto) I'm assuming that even though it is a fairly cheap part ($40), it is such a pain in the ass to replace that unless I'm planning a transmission rebuild it isn't worth the trouble? Quote Link to comment Share on other sites More sharing options...
Galaxie500XL Posted January 10, 2011 Report Share Posted January 10, 2011 Well, starting in '95, the side cover was redesigned to allow a transmission mount to be attached...which means there's lots of fun to be had. I figured my Cutlass has 207,000 miles on it, and the torque converter sounds like a coffee can full of rocks on takeoff, so I'm just going to rebuild the transmission. Quote Link to comment Share on other sites More sharing options...
WhatTheFehl Posted January 10, 2011 Author Report Share Posted January 10, 2011 With any luck this engine/transmission combination won't be in there a whole lot longer (really want a 3500 and haven't decided on transmission), though I'm not sure how much longer it will be before the car will be promoted from DD to project. In the meantime, I sure wish I could have the few MPGs that I'm losing because of this back. Quote Link to comment Share on other sites More sharing options...
Crazy K Posted January 11, 2011 Report Share Posted January 11, 2011 FOLLOW WOOL SMITHS ADVICE. The difference you feel or see of having or not having a working PWM is minimal. SIMPLE. EASY. STRAIGHT FORWARD. DO ET!!! I've done this on three transmissions and never looked back. you may also benefit from an auxiliary(external) transmission cooler... though saying that will bring someone like Bob out of the woodwork to argue....... Quote Link to comment Share on other sites More sharing options...
Galaxie500XL Posted January 11, 2011 Report Share Posted January 11, 2011 X2 on the cooler...I added one from a 3.8 Regal to my '95 LQ1, the cost was minimal, and keeps the transmission temp down long enough for me to make my usual commute back and forth to work each day without encountering the lockup issue. On long trips, though, especially in summer, 30 miles is about as far as I can drive before the PCM disables the TCC. Quote Link to comment Share on other sites More sharing options...
GM Guy Posted January 12, 2011 Report Share Posted January 12, 2011 Try what I suggested to Alec_b on the previous topic... this is exactly what happened with my 95 GP. Pulling up on the BP won't make a difference if the switch is worn. 95 should have a double plunger switch on the BP and can be adjusted. Occasionally it won't work and I just reach under and push on it and it will lockup the converter. Quote Link to comment Share on other sites More sharing options...
WhatTheFehl Posted February 8, 2011 Author Report Share Posted February 8, 2011 Which one of these is the "dark brown" wire? Or is this completely the wrong connector? Quote Link to comment Share on other sites More sharing options...
RobertISaar Posted April 14, 2011 Report Share Posted April 14, 2011 http://i.imgur.com/PzPx9.png http://i.imgur.com/UVgil.png TCC PWM is controlled via the circuit that is the "C" pin on the trans connector. should be one of two brown wires, the other is the fused TCC circuit, pin "E". should be easy to identify using the little connector end-view. Quote Link to comment Share on other sites More sharing options...
WhatTheFehl Posted April 17, 2011 Author Report Share Posted April 17, 2011 So... I cut the wire. 70 mph at ~2200 RPM... is that good now? And 60mph at ~2000... good? I definitely felt the TCC kick on this little trip. Quote Link to comment Share on other sites More sharing options...
RobertISaar Posted April 17, 2011 Report Share Posted April 17, 2011 sounds about right... even with the inherent inaccuracy of air-core tachs. Quote Link to comment Share on other sites More sharing options...
WhatTheFehl Posted April 17, 2011 Author Report Share Posted April 17, 2011 sounds about right... even with the inherent inaccuracy of air-core tachs. Good. And both of those numbers were with the cruise control set on the highway, on a fairly level plain. Quote Link to comment Share on other sites More sharing options...
tornado_735 Posted April 17, 2011 Report Share Posted April 17, 2011 So... I cut the wire. 70 mph at ~2200 RPM... is that good now? And 60mph at ~2000... good? I definitely felt the TCC kick on this little trip. That is about wat both of my L82/4t60e vehicles run so it looks right to me! Quote Link to comment Share on other sites More sharing options...
RobertISaar Posted April 17, 2011 Report Share Posted April 17, 2011 say hello to fuel economy. you might even hit the EPA estimates now. Quote Link to comment Share on other sites More sharing options...
WhatTheFehl Posted April 17, 2011 Author Report Share Posted April 17, 2011 say hello to fuel economy. you might even hit the EPA estimates now. I reset the DIC when I got home (the DIC has been pretty accurate for MPG on my car believe it or not, I've checked it with trip/fuel used a couple times and its been right on the money). Will post updated numbers tomorrow. Quote Link to comment Share on other sites More sharing options...
WhatTheFehl Posted April 18, 2011 Author Report Share Posted April 18, 2011 Driving complately non-carefully, non hypermile-y today (I even did a quick WOT run up a hill about halfway home)... DIC says I managed to eek out 20.3 mpg for my commute to/from work. Not bad at all. Quote Link to comment Share on other sites More sharing options...
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