[Ex Coal Miner]

Have searched, but haven't found anything useful to solve this.

The cruise control on my 99 Dakota, (5.2, auto) intermittently to fail when it’s the temp approaches 90 degrees with high humidity.

Sometimes when I press the on/off button, the cruise light will come for second or so, and then go out, never to be able to be turned on again until the engine is restarted. And sometimes, when i turn on the cruise but I have never set it, and I press the set button, the light goes out immediately and I have no cruise control until the engine is restarted.

I’m guessing this has something to do with the cruise control mechanism doing some initial checks, some reading or voltage check or vacuum or sensor fails to pass an initial check, and the system, by design, locks itself out until the engine is restarted. I’ve read some references to too-much-play in the cable, but now I can’t find that info anymore. An OBD
reading a local shop said was in the system one time after it happened pointed to a reply dropping out, but can't locate anything on that either. The high humidity aspect points to corroded contacts somewhere in an electrical connection, but yet I do not see the problem in wet and rainy conditions when the temps are cool or cold.

Any insights appreciated.

 

[Yuri Bevilacqua]

Look at the break pedal switch!!! This switch controls the cruise control and ABS system. Some times the break pedal do not return enough to close the switch completely. My Dodge RAM have the same symptoms that you have explained, and I discovered the solution by myself. Maybe you have to try to replace this switch.

 

[Ex Coal Miner]

Heat and Humidity?

Thanks, I'll look at this tomorrow. Why do you think the problem only happens during hot and humid weather, is the brake switch sensitive to these conditions?

 

[scubersteve]

the brake switch will not shut off the cruise light, only cancel the current setting. if the light is going off it is probably the cruise solenoid

 

[Ex Coal Miner]

It's not the brake pedal switch, it works fine, even disconnected, put an ohm-meter on it.

I'm beginning to suspect the cruise control cable. I read somewhere that there are several checks the cruise control unit does when first powered up, and if any fail, then the CC locks itself out until the engine is restarted. Unfortunately I can't locate where I read that interesting insight.