Smaay

before you all flame me, i have searched and searched. i cant seem to find the right answer. could be the sensor in the rear end, could be some switch on the brake pedal. I want to know exactly what it could be.

light comes on as soon as i hit about 40MPH and i loose me cruise control.

those that have fixed this problem, please provide part numbers for parts replaced and procedures to fix. im not a professional mechanic but i am engine savy and know what im doing.

Hodge

Check your vacuum lines. My truck did not do exactly as yours, but my cruise didn't work at all. I had a vacuum leak, not bad enough to disable things, but enough to mess up the ABS and render the cruise useless. Now both work great.

somis13

where was the leak? brake and abs lights have been on in my truck for years. I've replaced the rear wheel speed sensor(that wasn't it), brake light switch on the pedal(that wasn't it). basically I gave up. I put two pieces of electrical tape on the dash to cover the lights so I dont have to look at them. I would love to know what the prob is. I'm gonna watch this one.

Hodge

somis13, does your cruise work? If not, vacuum may be your problem. From the vacuum pump, start tracing the vacuum lines, and look for breaks. I did not fix mine- it was in the shop getting a transfercase put in, and they found it with a smoke machine. I hadn't looked for a bad vacuum line, because I didn't realize that the abs relied on vacuum. Fixed it, though.

patdaly

94-96 had a Vacuum switch to turn on the lights. Starting with the 97 Hydraboost, it went away, so no joy for you.

GAmes

Do you have a trailer brake controller? If so, will the light go off if you unplug it?

somis13

my cruise control works. yes I do have a brake controller, I've never tried to unplug it and see if the lights go off. here's the weird part. the lights only came on once the vehicle speed got over 50 m.p.h. and they stayed on til the truck was turned off. After I replaced the rear wheel speed sensor, they come on and stay on when the truck is started. i'll try unplugging the controller and let you know if that makes a diff. thanks

Smaay

my cruise doesnt work at all. well ill take that back, it work untill the light comes on. there might be a day when it does not come on and everything works just fine. i could be doing 60 on the freeway and then bam! the light comes on and the cruise cuts off.

on days that the light normall comes on, it usually lights up at about 40 MPH. this is so fustrating!

if anyone can post pictures on where all these sensors are that would help alot!

Hodge

Smaay, if your light comes on, and then the cruise goes off, you may want to check your brake light switch. Normally, touching the brake activates the brake lights, disengaging the cruise. Perhaps the brake light switch is not adjusted correctly, or is bad. Have you replaced the brake booster lately? Monkeying with the brake pedal, in reference to its interaction with the brake light switch, can warrant adjusting the switch.

The brake light switch is mounted in front of the brake pedal arm. When you push the brakes, the arm takes pressure off the switch plunger.

dodgeman01

Hers a weird one. My abs/brake light come on and off whether I'm on the gas pedal or off. when I get on it the light comes on when I let off or down shift the lights go off.
DM01

Smaay

Hodge, yes thats true if you hit the brake, but thats not the case here, the ABS light comes on too

Lil Dog

What year is the truck? I missed it.

Could be the wiring to the rear sensor as well. Mine had some severe rash from the gravel and I had to shrink sleeve the plug connection to the harness as it was pulling apart.

infidel

'98s are different than all the other 12 valves.
The light can come on if either the sensor on the rear differential or the one on the tranny/transfer case is bad.

Smaay

its a rare 98 12Valve. Infidel is there any chance you can post pics of these locations?

technolackey

Clock spring... same problem, and my mechanic told me its a broken clock spring whatever that is.