Transmission shudder going up slight hill

2002 MERCURY MARQUIS
165,000 MILES • 4.6L • V8 • AUTOMATIC
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CREME99
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ABS brake light on now was going off and on. Transmission shudders going up slight hill. can these be related or what might be problem? it does this in or out of overdrive. if you ease of the gas it shifts. this only does this in the last gear only not so bad on flat road.
Sep 3, 2017 at 6:01 PM
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STRAILER
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It sounds like you may have a transmission shaft speed sensor that has gone bad. To start lets read the codes to help us out.

Here is a guide to get us started:

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

Please let us know what you find.

Cheers, Ken
Sep 5, 2017 at 2:50 PM
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CREME99
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It doesn't have the check engine light and no codes. The lights are ABS and Brake. Is there a way to check the transmission speed sensor to see if it is failing? Thanks.
Sep 6, 2017 at 5:46 PM
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STRAILER
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It should throw a code if it is bad. Could it be the engine it misfiring causing the sensation the transmission is slipping, this is a common problem.

I don't think an ABS light will cause it to shutter. BTW check the brake fluid level if it is low you may have a leak or you need to replace the brakes.

Please let us know

Cheers, Ken


Sep 7, 2017 at 11:21 AM
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CREME99
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It kicks in and out of high gear when it shudders, feels like running over side of road there they put the ripples. ABS sensors, brakes, brake fluid have all been checked and ok. What tells transmission the speed and when to change from high to next lower gear?
Sep 8, 2017 at 3:50 PM
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STRAILER
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The computer controls the transmission. I would run the codes for the ABS to see what comes up to see if that could be causing it after all. Im kind of leaning toward the transmission having internal problems but its hard for me to tell without driving it.
Sep 9, 2017 at 10:44 AM
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CREME99
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Haven't been able to find a code reader that will read the ABS codes. Thanks. We have had 3 transmission mechanics drive it and they don't know what it might be unless it is a silenoid but didn't think that was the problem. We will keep trying to figure it out.
Sep 10, 2017 at 3:15 PM
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STRAILER
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It sounds like the transmission maybe worn out causing the problem. Please let us know what happens so it will help others.

Cheers, Ken
Sep 11, 2017 at 11:09 AM