95 Lesabre intermitint OD problem

[eeyore1]

I have a 95 Lesabre with 147,000 miles on it and 2000 miles on this tranny service. Was driving on the highway yesterday and kicked it into passing gear to get around someone but after I passed it did not want to go back into overdrive. I tried letting completely off of the gas and all that happened was RPMs dropped to 1500 but when throttle reapplied RPMs shot back up to around 3000. There was no slippage and I finally got it to shift by placing the car in neutral while I was coasting and turning car off then on and putting back into OD. I changed the fluid myself approx. 2000 miles back and it was still pretty healty(not burnt, no chunks in pan). No other problems with other gears and it has only done this a few times over the last 3 weeks and I really like this car but not willing to replace tranny. Any help will be greatly appreciated!!!

[troy1]

Does it still not shift into 4th? You need to go have the car scanned and retrieve any codes stored.

[eeyore1]

It does shift into OD but occasionally I have to assist it or it will not and I am still working on taking it to a shop. I work 2 shift so it takes some planning to get it there.

[hkmorgan87]

My 95 lesabre does the same thing. When my overdrive decides to turn off and the rpms jump up, I end up having to pull over because my OD doesn't reengage. Which also sets off the check engine light. i turn off my car, restart, and the check engine light goes off and the car works fine again

[HotZ28]

If I remember correctly, there were two TSB’s on the mid 90’s (92-96) 4T60E transmission. The first one was, the transmission may drop out of drive while cruising, shift erratically, or have no second, third, or fourth gear because of a bad ground connection for the shift solenoids. The second one was the transmission would suddenly go into neutral at highway speeds, due to a problem with internal shift valves. One or the other should show a code and point you in the right direction.

[hkmorgan87]

My car doesn't do either of those things. Well maybe possibly part of the first option, but given when the car does this to me, i dont think it could be a shift solenoid, but then again maybe it is. So when my tranny sets a code in my computer, and I reboot, does the code go away, bc the service engine light turns off. or is the code stored until a tech removes it.

[BNaylor]

Originally Posted by hkmorgan87

My car doesn't do either of those things. Well maybe possibly part of the first option, but given when the car does this to me, i dont think it could be a shift solenoid, but then again maybe it is. So when my tranny sets a code in my computer, and I reboot, does the code go away, bc the service engine light turns off. or is the code stored until a tech removes it.

Contrary to your belief a flaky shift solenoid may totally inhibit 4th gear (OD). When the respective DTC sets certain actions are taken. This includes disabling shift adapts, commanding maximum line pressure, defaulting to 3rd gear and inhibiting TCC operation.

In your case the best time to scan with a trans capable scanner is when the SES/CEL illuminates. However, active DTCs and history codes may be present regardless of a reset. There are 3 DTC types, A, B, and D. Most trigger the SES light and some do not. Certain Torque Convertor Clutch (TCC) and Shift Solenoid DTC/faults specifically a 2-3 shift solenoid malfunction will inhibit OD and TCC lock/unlock function.

Therefore, best thing to do is get scanned.

[eeyore1]

Okay here I am 3months later and still tranny not working correctly. I had it scanned and there were no codes stored. From what I have gathered it seems it could be a sticking B solenoid, does this sound feasible to you guys. I was a little off on original post. Car shifts smoothly from 1-2 at approx. 20 mph but then fails to shift 2-3 sometimes. Also when driving in town at around 40mph if I let off the gas there seems to be no downshift and if I reapply throttle then the RPMS jump up to where they were when I was holding the throttle. Items replaced VSS, TPS, did ohm checks at tranny connector all checked fine. Check for shorts to ground at tranny connector and everything checked out ok. It has never lit up the SES light and as I said there have been no codes stored. I can' help but think it is an electrical problem because of the intermittent fault. I am considering replacing the PCM because I can get one for 20 bucks and it is easier to get to than the solenoids. Also I have checked for vaccum leaks and found nothing. One more thing a couple weeks after this all started I had to replace the alternator and I unknowingly put a bad one on that went out about a week later now I have put on a known good alternator and the problem is still there. I was wondering if the bad alternator could have possible damaged the PCM. I am getting long winded so I will let you guys chew on that for awhile. Thanks in advance.

[eeyore1]

Almost forgot if I am on the highway and it doens't shift to 3 then I can place car in neutral and turn ignition off and restart car place gear selector in OD and car will shift to OD and be fine. Also I tried disconnecting the trans connector and putting car in drive and this tells me that 3 gear is operational as I understand it.

[maxwedge]

The only way to find this is get a trans function scanner on it and while driving you can command the various solenoids and see if they operate, also look at gear and slippage errors.