Help with a cruise control issue
Thread Starter
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BANNED!!!
Joined: May 2017
Posts: 14,837
Likes: 2,497
From: Washington State
Coupe 6MT Premium RAS
Help with a cruise control issue
I've hit a wall troubleshooting a possible issue with my cruise control. It's functions perfectly on level grade or on an incline, the problem I have is when it's decelerating the vehicle on a downhill incline.
Here is what I "feel" in the vehicle. It feels like someone is pushing the brakes for 1 second then releasing them, it is a repeating pattern such as:
-Brakes for 1 second
-Coast for 1 second
-Brakes for 1 second
Here is what I "feel" in the vehicle. It feels like someone is pushing the brakes for 1 second then releasing them, it is a repeating pattern such as:
-Brakes for 1 second
-Coast for 1 second
-Brakes for 1 second
-Coast for 1 second
-Rinse/repeat until I am no longer going downhill and needing to decelerate.
I know the cruise is handled by the ecu and controlled via the throttle position motor, I've gone through all steps of the FSM that don't require consult2, I've checked for slop in the driveling and axle, I've checked for worn bushings possibly causing axle movement.
Also of note, it doesn't actually feel like the throttle is being used to control speed, the rate of deceleration during the 1 second pulse actually feels like the BRAKES are being engaged to slow the vehicle, it literally feels like someone pushing the brakes for 1 second, every other second.
-Rinse/repeat until I am no longer going downhill and needing to decelerate.
I know the cruise is handled by the ecu and controlled via the throttle position motor, I've gone through all steps of the FSM that don't require consult2, I've checked for slop in the driveling and axle, I've checked for worn bushings possibly causing axle movement.
Also of note, it doesn't actually feel like the throttle is being used to control speed, the rate of deceleration during the 1 second pulse actually feels like the BRAKES are being engaged to slow the vehicle, it literally feels like someone pushing the brakes for 1 second, every other second.
Registered User
Joined: Jun 2013
Posts: 829
Likes: 99
From: Tampa, Fl
Don't the brakes or something work with the cruise control to control a steady speed downhill? I don't use cruise control much but I'm pretty sure I've seen my brake lights come on with cruise control set
Joined: Mar 2013
Posts: 2,001
Likes: 390
From: Raleigh, NC
Coupe, Premium package, sport suspension
How steep are your hills? I can definitely tell brakes are part of the cruise system, but it's not as dramatic as what you are describing. Much more subtle.
Thread Starter
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BANNED!!!
Joined: May 2017
Posts: 14,837
Likes: 2,497
From: Washington State
Coupe 6MT Premium RAS
Pretty steep in places, I drive through the Horse Heaven Hills as part of my daily commute but the biggest decline is maybe 8-10% grade, it only happens on the steeper parts.