Torque converter not locking up

[Ksniem]

What’s up guys,

Been having issues with my torque converter not staying in lockup. It will kick in and out every so often while cruising, but majority of the time runs out of lockup, going into lockup is rare. This happened after my computer was reflashed with the latest update. Under the trucks factory VCI it ran fine, and unfortunately I can’t flash it back to that software, or at least don’t know if a way how. However I can command lockup via scan tool and it works fine. Anyone have any ideas?

Thanks


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[whiteboyslo]

Do you have cruise and does it work? The brake light switch can go faulty, making the truck think the brakes are being applied. This will keep the cruise from engaging and will also keep the converter from locking.

Mike

 

[thunderstruck]

If it's not that brake switch, could be a faulty throttle position sensor.

What year model we talking about here? I forget which year it started, but you might have PWM lockup. Wonderful garbage engineering from GM.

 

[Supercharged111]

If it's not that brake switch, could be a faulty throttle position sensor.

What year model we talking about here? I forget which year it started, but you might have PWM lockup. Wonderful garbage engineering from GM.

If that's the case, there are cheap mechanical ways to disable PWM and have just lock/unlock. The lockup rates are lazy from GM anyway.

 

[Ksniem]

It’s a 97, yes my cruise works. Gonna have a rookie question here.. what’s PWM? And the manual fix? Never gave the brake switch a thought


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[Supercharged111]

For a 97 you have PWM. Shift kit will eliminate itm

 

[c1500deathtrap]

Must be related to OJ if it won't stay locked up.

 

[Ksniem]

Thankfully it’s not a bronco.. lol any other suggestions or is that about it?


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[Ksniem]

Is it worth trying to replace the solenoid if that’s the root of my issue?


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[Biggershaft96]

Stupid question but does your truck get up to operating temp?