Rocketman Posted March 9, 2010 Report Share Posted March 9, 2010 Hi all, I've been a member for a while, I had a '94 GP SE a few years back, recently I picked up a 1995 GP SE and its great to be driving one again. Its a 3100 w/ 122k miles, Have an issue- MY TCC isn't locking up once the car is warm. I've been reading that the tranny could be too hot, but its the winter...why would this occur? The fluid is pretty trashed in it, I drained out some and put fresh fluid in to no effect. I'll be dropping the pan to do filter/fluid once I get some warmer weather. Its not limp mode - I can manual downshift to third and it will shift to 3rd - I have 4th gear, just not lockup I've seen people talk about aftermarket oil coolers - definitely will go this route if needed but is there something I should be looking at? Thanks guys- Matt Quote Link to comment Share on other sites More sharing options...
BXX Posted March 9, 2010 Report Share Posted March 9, 2010 If your fluid is crap, then thats your problem. Unless an entire fluid exhange is done with a new filter, your not gonna have good results. And theres a change the TCC is just trashed or the solenoid is junk. First start with fluid and a filter. Quote Link to comment Share on other sites More sharing options...
Galaxie500XL Posted March 9, 2010 Report Share Posted March 9, 2010 I have a similar issue with my '95 LQ1 Cutlass Convertible. Once the transmission fluid temperature rises above 179 degrees, I have no lockup. However, what's supposed to happen in this case is the ECM commands the transmission to disable overdrive, and run up to 3rd gear only. The ECM then sets a code P0740, which I can read on my scantool. A P0740 will NOT light the "service engine soon" light, you'll only see the code with a scanner. Are you certain you still have 4th gear? If you do have 4th, it is possible that your gear selector switch is misaligned, inhibiting lockup. Like you, I decided to add a transmission cooler, and added the GM transmission cooler put in certain Regals with the 3.8. What I found is that while it does reduce fluid temperatures, the temperature still goes above the threshold that causes my problem, only 15-20 minutes later than before. Quote Link to comment Share on other sites More sharing options...
Brian P Posted March 9, 2010 Report Share Posted March 9, 2010 This seems to be most common on '95 model years. There are two solenoids for operation of the torque converter clutch- The apply/release solenoid, and the PWM solenoid. The PWM solenoid's only function is to soften the apply and release of the clutch (in later years it's used to allow a little bit of slip under load, but that doesn't apply to the '95's). The PWM is known to be faulty and cause major slipping when the fluid is at operating temp, and in worst cases, stop the clutch application all together. The fix that worked for me (back when I had my original transmission) was to cut the control wire for the PWM solenoid. If you look at the transmission harness, it's the front plug just above the vacuum modulator. Quote Link to comment Share on other sites More sharing options...
Galaxie500XL Posted March 9, 2010 Report Share Posted March 9, 2010 Brian; Did this create any issues, or touble codes? I've never seen this idea before. This seems to be most common on '95 model years. There are two solenoids for operation of the torque converter clutch- The apply/release solenoid, and the PWM solenoid. The PWM solenoid's only function is to soften the apply and release of the clutch (in later years it's used to allow a little bit of slip under load, but that doesn't apply to the '95's). The PWM is known to be faulty and cause major slipping when the fluid is at operating temp, and in worst cases, stop the clutch application all together. The fix that worked for me (back when I had my original transmission) was to cut the control wire for the PWM solenoid. If you look at the transmission harness, it's the front plug just above the vacuum modulator. Quote Link to comment Share on other sites More sharing options...
Brian P Posted March 9, 2010 Report Share Posted March 9, 2010 I need to edit that the control wire is *IN* the front plug, not the front plug entirely. I think it was pinout "C". Never got any trouble codes for the problem or the fix. Quote Link to comment Share on other sites More sharing options...
Rocketman Posted March 9, 2010 Author Report Share Posted March 9, 2010 I have a filter kit on the way - just starting to get nice weather this week. I'll get it changed soon if the weather holds out. Thanks Quote Link to comment Share on other sites More sharing options...
alec_b Posted March 11, 2010 Report Share Posted March 11, 2010 Boy you must have my car's cousin! My '95 does the same thing. Although it doesn't happen every time it still does it. I still have 4th gear and don't get any SES light. I need to change my fluid/filter too (100k, original). Hopefully that and some lucas will help. Otherwise, maybe I'll just cut that PWM wire. I don't care if the TCC kicks a little when it engages, so long as I know that it's engaged all the way. Quote Link to comment Share on other sites More sharing options...
Rocketman Posted March 25, 2010 Author Report Share Posted March 25, 2010 Okay - an update. Changed the filter yesterday morning, replaced fluid with new - transmission still will not lockup in 4th. Does fine when its cold. I have a small aux cooler off another vehicle I'm going to install today to see if it has any effect. Failing that, I will clip the wire for the PWM. This is just another reason why I hate automatics, lol. EDIT: Decided to clip the wire to the PWM first. Less involved and easily reversible. So far so good, TCC lockup is more abrupt than before, but it does lockup even after warming up and a couple 'spirited' drives down backroads. So that leaves the question - whats wrong with the PWM solenoid then? I'm fine with it as long as its working and I can get lockup on the highway - I'm after those extra couple MPG's... but whats the issue to begin with? Anyway thanks Brian for the diagram and the 'solution'. Probably going to install the oil cooler anyways for good measure. Quote Link to comment Share on other sites More sharing options...
alec_b Posted March 26, 2010 Report Share Posted March 26, 2010 Rocketman- How much more abrupt is the TCC lockup? Not that I mind, I'd rather have it firm than mushy or inoperable. I'm just curious. Quote Link to comment Share on other sites More sharing options...
Rocketman Posted March 26, 2010 Author Report Share Posted March 26, 2010 It actually kind of feels like a firmer 'shift' its not bad at all. Also depends on what the car is doing, seems like its a lil firmer when going up a slight incline Quote Link to comment Share on other sites More sharing options...
Crazy K Posted March 26, 2010 Report Share Posted March 26, 2010 I have had to cut the PWM wire on a car too. All it does is tries to soften the shift, but when the solenoid starts acting up it causes issues. The difference between a car with a good PWM solenoid and a disabled one is so slight I don't think it really matter much... it feels like a slightly snappier shift without the PWM, if you even notice a difference at all. and yes, add the tranny cooler. Quote Link to comment Share on other sites More sharing options...
Galaxie500XL Posted March 26, 2010 Report Share Posted March 26, 2010 Let us know about the mileage, too, once you know. My '95 LQ1 gets terrible mileage, partly due to this same issue. If you experience no problems, and improved mileage, I'd be inclined to snip mine. Okay - an update. Changed the filter yesterday morning, replaced fluid with new - transmission still will not lockup in 4th. Does fine when its cold. I have a small aux cooler off another vehicle I'm going to install today to see if it has any effect. Failing that, I will clip the wire for the PWM. This is just another reason why I hate automatics, lol. EDIT: Decided to clip the wire to the PWM first. Less involved and easily reversible. So far so good, TCC lockup is more abrupt than before, but it does lockup even after warming up and a couple 'spirited' drives down backroads. So that leaves the question - whats wrong with the PWM solenoid then? I'm fine with it as long as its working and I can get lockup on the highway - I'm after those extra couple MPG's... but whats the issue to begin with? Anyway thanks Brian for the diagram and the 'solution'. Probably going to install the oil cooler anyways for good measure. Quote Link to comment Share on other sites More sharing options...
Rocketman Posted March 27, 2010 Author Report Share Posted March 27, 2010 So far I've burned about a half a tank of gas... My DIC used to read 19 to 20mpg on average, combined, now its reading around 24mpg. I track my mileage manually as well the DIC is usually accurate within .5 mpg Highway it seems like I'm getting close to 26, which is much more acceptable, I havent been able to top 23mpg yet. Sweet spot seems to be around 70 - 75 mph and the ride is so much smoother without the engine ripping those extra RPMs Will report back after burning another tank or so Quote Link to comment Share on other sites More sharing options...
DavidHowell3633 Posted March 31, 2010 Report Share Posted March 31, 2010 Glad you are having success and making progress. My solution was a fine adjustment to the neutral safety switch after fluid changes and trans cooler. The two bolts need some Loctite or equivalent. Adjust the switch until you can start the car in Neutral and the back up light are on in R. Even then, it might need a 1/32 " move. Strange no one else had this NSS problem, but that's the nature of the beast, I guess. Quote Link to comment Share on other sites More sharing options...
Galaxie500XL Posted March 31, 2010 Report Share Posted March 31, 2010 Thanks for the update! Keep us posted on what you find after driving it awhile, and your mileage after a few tanks. Quote Link to comment Share on other sites More sharing options...
Brian P Posted April 1, 2010 Report Share Posted April 1, 2010 Good to hear it worked. It's really not worth digging into the tranny to replace that solenoid when all it does is soften the TCC engaging. The '96+ tranny's don't seem to have this issue so it must have been a bad batch of solenoids in '95. Quote Link to comment Share on other sites More sharing options...
jesterx888 Posted May 11, 2010 Report Share Posted May 11, 2010 How has the car been lately? Is your trans issue gone? I am thinking about clipping my pwm wire... So far I've burned about a half a tank of gas... My DIC used to read 19 to 20mpg on average, combined, now its reading around 24mpg. I track my mileage manually as well the DIC is usually accurate within .5 mpg Highway it seems like I'm getting close to 26, which is much more acceptable, I havent been able to top 23mpg yet. Sweet spot seems to be around 70 - 75 mph and the ride is so much smoother without the engine ripping those extra RPMs Will report back after burning another tank or so Quote Link to comment Share on other sites More sharing options...
Rocketman Posted May 11, 2010 Author Report Share Posted May 11, 2010 Car has been fine...hit 31mpg on a recent trip to baltimore from my place in NE PA... having a small intermittent issue which is seemingly unrelated, see here: http://www.w-body.com/showthread.php/46352-More-Transmission-Woes... otherwise so far so good, pwm clip works real well Quote Link to comment Share on other sites More sharing options...
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