Engine/Transmission (1994 - 1998) Another TC Lockup Problem

[SBozeman]

Does anyone have an idea what would be causing early lock up? Tried a lot of different things with no luck. The TC is locking up as early as 23mph with OD off. It should not lockup until 35 mph under light throttle. Checked and adjusted TPS voltage and TV cable. Pulled TPS wiring out of the loom about 18 inches. Checked and cleaned all connectors on transmission and VSS. Thought it might be lockup solenoid but the problem was present prior to recent transmission upgrades. I have not been able to find much on the TDR regarding early lockup. Most symptoms are associated with in and out of lock up at freeway speeds. I have not experienced that problem. Any other ideas would be appreciated.



Thanks

Steve

 

[bmoeller]

Originally posted by SBozeman

Thought it might be lockup solenoid but the problem was present prior to recent transmission upgrades.

Did they replace the solenoid and pressure sensor though?



I wonder if there is a reflash for the PCM to correct the programing



Maybe all you need to do is lock out O/D with the switch, then wait 'til 45-50mph. and engage it. Locking it out of O/D in town would be good idea too.

 

[champspa]

mine locks up at 29 under light throttle and 48 in od.

 

[SBozeman]

Originally posted by bmoeller

Did they replace the solenoid and pressure sensor though?



I wonder if there is a reflash for the PCM to correct the programing



Maybe all you need to do is lock out O/D with the switch, then wait 'til 45-50mph. and engage it. Locking it out of O/D in town would be good idea too.

Not sure. I thought that a solenoid and pressure sensor came with the new VB.



As far as locking out the OD in town. That's the problem, it locks up early with OD off under light throttle. It is quite a jolt when loaded.

 

[JohnE]

PCM commands lock-up and the trany responds once in third gear so it could be either. Have you checked the TPS voltage? It may be set wrong.



Doesn't the ATS controller have a setting to unlock below a set road speed?



I have a PCM issue that causes a quick 2nd-3rd shift. With light throttle position and O/D disabled is TC lockup is around 30 mph and slightly over 45 mph in O/D.

 

[bmoeller]

Originally posted by SBozeman

As far as locking out the OD in town. That's the problem, it locks up early with OD off under light throttle. It is quite a jolt when loaded.

That should be 3rd gear lock-up with the O/D off, normal.



Do you have 4. 10s or 3. 54s? Hasn't been a problem with a jolt on mine loaded or empty. I have 4. 10s myself.

 

[SBozeman]

3. 54s



TPS Voltage was low around . 73 volts. I adjusted it to 1. 4V. TC would not unlock when I took my foot off the throttle so readjusted it to the recommended stock setting of 1. 2V. Seems better now but still has not solved my early lockup problem.



The service manual indicates that it should not lockup until 35 mph at light throttle OD off and 45 mph light throttle OD on. That's the way I remember it working when it was new. The jolt is when I'm at medium throttle around 28 to 30 mph and it locks up. I know it's because that is too early to be locking up under that much throttle.



I don't think it is related to the ATS controller because the problem existed prior to installation but seems to have become more pronounced after the install. Besides, the TC lockup schedule is suppose to revert to stock with the controller turned off.



The only trouble shooting condition listed in the manual that comes close is: "TC locks up in second and/or third gear". Possible causes listed are "lockup solenoid, relay or wiring shorted/open". Would anyone happen to know where the relay is their talking about? Is it part of the solenoid? Is it located in the VB?



Thanks Again

Steve

 

[bmoeller]

The relay MIGHT be in the PDC. Don't have my FSM handy or to go out and look in the dark. The lock up solenoid and pressure sensor are attached to the VB.



35mph lock up, w/O/D off. Hmmmm. Sounds like mine may be off a little. Mine locks about 30mph. Don't know if 4. 10s would have an effect on that though.