Engine/Transmission (1998.5 - 2002) Torque converter stays unlocked up

[DPelzl]

Ok I have done my searches and haven't found anyone with this problem. This issue has been going on for a few years and it is very consistent. When accelerating my truck shifts into second gear the torque converter locks up immediately then stays locked up until I slow down enough to get back to 1st gear then it disengages. If I am in 2nd or 3rd and let off the gas it will slow with full lockup then down shift still locked up until first gear and unlocks. If I am in overdrive when I get off the gas it will slow and start to lug around 30-35mph before it will downshift or I hit the overdrive button and it downshifts as explained before with the converter locked. I do have a torque converter switch installed but with it engaged the trans/torque converter acts the same except shifts are firmer. One other thing when the truck is warm and I am pushing it hard or towing the torque converter lockup will sometimes be delayed until 3rd gear but once locked up it stays locked. Any ideas??? also throwing a p1740.

 

[SnoKing]

Could be the torque converter solenoid or a PCM problem. Rewire your switch to a center off double throw switch and open the lead to the solenoid lead and see if it unlocks. Snoking

 

[SnoKing]

PCM -
•••••••••••\
Open --+ } Solenoid Lead
•••••••••••/
Ground-

 

[cerberusiam]

Disconnect the lockup switch and see if you have it wired wrong.

If that does nothing I think you have a problem in the transmission that you need to get back to the builder on. If you feel a difference in the shift with lockup switch on and off and the TC is not fully locking with the switch off.

Beyond that without knowing exactly how the VB was setup it is too hard to tell what the problem could be.

 

[DPelzl]

I was going to wire the switch up as you suggested but I didn't want to have to cut the wire. I guess I should try it. The lockup issue was way before I installed the switch. I am pretty sure the torque converter is locking up fully. There is no slippage or rpm fluctuation once it locks. I have actually gotten used to the way the truck drives. But I am concerned something bad is going to happen one of these days, probably when I am towing like the injection pump a few years back! Thanks for the reply, if you or anyone else have any suggestions I am open to hear them.