• NAXJA is having its 18th annual March Membership Drive!!!
    Everyone who joins or renews during March will be entered into a drawing!
    More Information - Join/Renew
  • Welcome to the new NAXJA Forum! If your password does not work, please use "Forgot your password?" link on the log-in page. Please feel free to reach out to [email protected] if we can provide any assistance.

97 XJ Cruise Control keeps increasing in speed?

Patriotsix

NAXJA Forum User
I have a 97 4.0 Auto XJ. The cruise control worked when I got it recently but now it always wants to slowly and steadily increase in speed when I set the cruise control. It would keep going up until it can't any more. I usually just cut it off at 80. What could it be?


Sent from my iPhone using Tapatalk
 
check all the vacuum lines for leaks. the manual says it should have atleast 10 inhg.

or it could be this.

OVERSHOOT/UNDERSHOOT FOLLOWING
SPEED CONTROL SET
If the operator repeatedly presses and releases the
set button with their foot off of the accelerator (a “lift
foot set” to begin speed control operation), the vehicle
may accelerate and exceed the desired set speed by
up to 5 MPH (8 km/h) and then decelerate to less
than the desired set speed before finally achieving
the desired set speed.
The Speed Control has an adaptive strategy that
compensates for vehicle-to-vehicle variations in speed
control cable lengths. When the speed control is set
with the vehicle operators foot off of the accelerator
pedal, the speed control thinks there is excessive
speed control cable slack and adapts. If the lift foot
sets are continually used, the speed control overshoot/undershoot condition will develop.
To “unlearn” the overshoot/undershoot condition,
the vehicle operator has to press and release the set
button while maintaining the desired set speed with
the accelerator pedal (not decelerating or accelerating), and then turn the cruise control switch to the
OFF position (or press the CANCEL button if
equipped) after waiting 10 seconds. This procedure
must be performed approximately 10–15 times to
completely unlearn the overshoot/undershoot condition
 
there is 1 that goes to the speed control servo on the passengers side fender. im not sure if it would cause the problem but just make sure its not dried out and cracked.
 
My bet is on the control module. The electronics can drift over time.
 
Elaborate please? What is and where is the control module? Thanks
In the early days, speed controls were made mainly from analog circuitry. Analog circuits drift with time and temperature, unlike the newer digital circuits.

Back in the day, if you got an aftermarket speed control, it had a control to compensate for the drift that you had to adjust.
 
Back
Top