Cruise control disengages when road is bumpy or weather/engine is hot

2002 Honda Civic LX

Around 1 or 2 years ago, cruise control has started acting strangely. If weather or the engine are cold, and the road is smooth, then it works fine. However, in hot weather, or if the engine is hot, cruise control disengages and the car just slows down as if someone turned CC off. Sometimes this happens randomly, other times it’s helped by a nudge from a bump in the road.

If I try to re-engage CC, it doesn’t work. I have to reach to the CC master switch, turn that off, then back on, and then CC starts working again for a while - until I hit the next bump or something.

The problem seems to be getting slowly worse as time goes by. At first I had this problem in the middle of summer. Now CC is affected even in winter (or what passes for winter in California).

What could possibly cause this? If it’s something that could be fixed by just replacing some component, I’d rather do it myself. But I don’t know what part might be the culprit.


First thing to check is the brake light switch. The cruise control uses the brake light switch on the brake pedal assembly to cancel the cruise function. A badly adjusted or damaged brake switch can cause all kinds of C-C problems.

More details:

Often the CC light will stay on while the speed of the vehicle decreases - at least for a while. It slows down a bit, sometimes it would buck like a wild horse, slow down, jump ahead, slow down again, etc, a few times, until at the end it settles into a slow deceleration - and only then would the green CC light turn off.

Other times it just begins to slow down and it decelerates smoothly - but even then the green light stays on for a few seconds, and then it turns off.

There’s another factor that seems to trigger this issue: it also tends to disengage when the road goes uphill, even if it’s not too steep of a climb.

Would all these symptoms be caused by a bad switch? It seems to me it should either disconnect or not.

+1 for @BustedKnuckles.

Sounds like the cruise control module is failing. A Honda shop or dealer can probably retrieve codes from the C-C module. I know Autozone or any other parts store cannot.

I wonder, how does the CC throttle control function work in this car? Is there a separate CC actuator motor to control the throttle, or is throttle control done with the CC module telling the ECM to control an in-motor throttle actuator motor? In any event, the problem could be the actuator motor is failing. Some of these I expect are electrical stepper motors, and others may have the engine vaccum as the power source. So it could be something more than just the brake pedal switch, but less complicated than a total CC electronics module failure. If the OP’s car uses engine vacuum as the power source for the actuator, that might be fairly simple to check.

Actually, I’ve heard about the vacuum actuators before. Someone has mentioned that possibility a while ago (different context, not here).

What does the actuator look like, and where is it located? And how could I test it?