Cruise

[NDBirdman]

2002 Ranger, 4.0, 134k miles. Picked up this truck as a daily driver, fun little truck to drive. It has a problem with the cruise control. In the mornings, it works good until the outside temp warms up, then it kicks off and will not re-engage. Any time I try to use it during the warm part of the day, no go, not even a flash of the light. Now it is getting chilly out during most the day, it works good, again, until it gets warm out.

Question is, what would cause the cruise to work when cold out, but not when the days are warm?

 

[adsm08]

First suspect, in my mind, is the pressure deactivation switch on the master cylinder. They are known for causing all sorts weird things like intermittent cruise operation and fires.

I would try replacing that first because it is easy and cheap and a known common failure item.

 

[RonD]

Welcome to TRS

Most likely the Cruise amplifier/servo, it is in the engine bay so gets warm

Video here on Cruise servo unit: www.youtube.com/watch?v=RunKPb7oNIM

The in cab wiring/buttons stay at same temp most of the time no big swings in temp
Engine bay does have a big swing in temp

And if you can find servo for under $50 then I would just swap it out

 

[adsm08]

Welcome to TRS

Most likely the Cruise amplifier/servo, it is in the engine bay so gets warm

Video here on Cruise servo unit: www.youtube.com/watch?v=RunKPb7oNIM

The in cab wiring/buttons stay at same temp most of the time no big swings in temp
Engine bay does have a big swing in temp

And if you can find servo for under $50 then I would just swap it out

While not impossible, my experience has been that type of failure usually results in the light coming on with no actual actuation from the cruise system.