2000 ram 1500 cruise not working

Mattx15 said:

i have a 2000 dodge ram 1500 5.9 all stock, the cruise control recently quit working and i went down the list of diagnosis, steering wheel buttons swapped theyre good, tested vacuum all good. im down to the brake light switch, i noticed the cruise control light on the dash will only come on while i am pressing the brake pedal, as soon as i release the brake the cruise light turns off so i am assuming its the brake switch??? any help is much appreciated.

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dudeman2009 said:

The brake switch in the resting position allows power to flow from the PCM to the speed control servo. When the brake is depressed, the power flow to the speed control solenoids is cut. This results in the dump solenoid returning to its naturally off position, which is to release the vacuum.

In the brake pedal resting state there should be continuity between the yellow/red wire and the dark blue/red wire. When the pedal is depressed, there should be no continuity.Power is supplied on the yellow/red wire from the PCM. To test this, start with the key off. Turn the key to run and wait for all the dash lights to return to normal. Push the cruise button all the way once. Check for voltage on the yellow/red wire, it should be either 5 or 12V. Do not use a test light, only a DMM.

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Mattx15 said:

i dont have a dmm but i replaced the brake light switch to see if it would help, it did not, it just confuses me how it is operating opposite of how it should, it should turn on normally then turn off when the brake pedal is depressed but its turning on only when its depressed and turns off when you let go of the brake pedal, its been like this for a few months, it just started to happen when i went to use it while driving one day, never worked since. could my servo be bad?

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dudeman2009 said:

I wouldn't go there yet. If you replace that, its probably going to have the same effect as replacing the brake pedal.

The picture is what we are working with here. When the brake switch is depressed the light goes out. Except thats not what should happen. You can try unplugging the cruise servo and seeing if the light will turn on then when the brake isn't depressed. Also, the light should remain on at all times, even with the brake depressed. Without a DMM its hard to tell what is happening, and even harder to try to fix it without wasting a bunch of money. If there is a harbor freight near you, you can buy a $10 DMM that will work.

What I would do is unplug the cruise servo and see if the light on the dash will light. If it does, then plug in the servo while the light is on. If it goes out, then without further testing, you will have to replace the servo. If it doesn't light when the servo is unplugged, then that is not your issue. Something else is.

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Mattx15 said:

unplugged the servo and the cruise light still did the same thing , i pulled a code p1595 cruise control solenoid open or shorted both when it was plugged in and un plugged, so if my solenoid is good it has to be a wire shorted somewhere right? i never got around to testing with a dmm im just not good with that wiring stuff so if i do get a dmm how to i go about testing the cruise wiring harness to check for a short?

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