# Automatic transmission lock-up problem

**URL:** <https://community.cartalk.com/t/automatic-transmission-lock-up-problem/25812>\
**Category:** Maintenance/Repairs\
**Tags:** clutches\
**Created:** [January 31, 2009, 1:36am UTC](https://community.cartalk.com/t/automatic-transmission-lock-up-problem/25812 "2009-01-31T01:36:42Z")\
**Posts on this page:** 6\
**Page:** 1

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**Author:** ![98Jeep](https://avatars.discourse-cdn.com/v4/letter/9/8797f3/32.png) [@98Jeep](https://community.cartalk.com/u/98Jeep)\
**Post date:** [January 31, 2009, 1:36am UTC](https://community.cartalk.com/t/automatic-transmission-lock-up-problem/25812/1 "2009-01-31T01:36:42Z")

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The lock-up clutch in the automatic transmission in my 1998 Jeep Grand Cherokee will momentarily and randomly disengage when driving at a steady speed on level roads (initial discussion approx 1/9/09) and I would like to buy a good transmission book/manual to check-out/investigate some of the possible causes suggested to date. Please inform me where I can find this type of book/manual.

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**Author:** ![Tester](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/tester/32/15976_2.png) [@Tester](https://community.cartalk.com/u/Tester)\
**Post date:** [January 31, 2009, 2:01am UTC](https://community.cartalk.com/t/automatic-transmission-lock-up-problem/25812/2 "2009-01-31T02:01:56Z")

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Before going through all that, make sure the brake light/interlock switch isn’t the problem.

You know that when you step on the brake pedal the lock-up torque converter disengages? If you have a switch that’s effected by vibration and turning the brake lights on and off, the same thing happens with the torque converter clutch.

Tester

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**Author:** ![98Jeep](https://avatars.discourse-cdn.com/v4/letter/9/8797f3/32.png) [@98Jeep](https://community.cartalk.com/u/98Jeep)\
**Post date:** [January 31, 2009, 3:53am UTC](https://community.cartalk.com/t/automatic-transmission-lock-up-problem/25812/3 "2009-01-31T03:53:31Z")

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Thanks for your suggestion - how can I determine if this is the cause of my problem?

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**Author:** ![Tester](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/tester/32/15976_2.png) [@Tester](https://community.cartalk.com/u/Tester)\
**Post date:** [January 31, 2009, 3:42pm UTC](https://community.cartalk.com/t/automatic-transmission-lock-up-problem/25812/4 "2009-01-31T15:42:44Z")

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The next time the TCC starts disengaging, slip your left foot behind the brake pedal and lift up on the pedal. If the TCC remains engaged there’s a problem with the brake light switch.

Tester

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**Author:** ![transman618](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/transman618/32/24_2.png) [@transman618](https://community.cartalk.com/u/transman618)\
**Post date:** [January 31, 2009, 11:44pm UTC](https://community.cartalk.com/t/automatic-transmission-lock-up-problem/25812/5 "2009-01-31T23:44:10Z")

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Why did you start a second thread on the same subject? We addressed the brake light switch in the last thread…

transman

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**Author:** ![98Jeep](https://avatars.discourse-cdn.com/v4/letter/9/8797f3/32.png) [@98Jeep](https://community.cartalk.com/u/98Jeep)\
**Post date:** [February 2, 2009, 4:22am UTC](https://community.cartalk.com/t/automatic-transmission-lock-up-problem/25812/6 "2009-02-02T04:22:02Z")

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I appreciate the suggestions on my first question (i.e. disengagement of the the lock-up clutch) but now I am searching for a suggested transmission book/manual that I can use for following up on the initial suggestions and troubleshooting techniques.