2008 LMM, dsp5 tuned, now no cruise & service trailer brake light

[Yellow Jacket]

I tuned a 2008 LMM 3500 Dually a couple weeks ago, I ran a script on the file like I do for my LMM tunes... Now customer says cruise doesn't work and Service Trailer Brakes message is displayed...

I made sure I plugged brake back in after removing panel to install dsp5 switch.

Is there something obvious I could've done in the tune? I upgraded his original OS that I read with EFILive and ran a script... So I don't have reason to believe it's an OS error... Remote Start & High Idle still work...

 

[x MadMAX DIESEL]

2008 LMM, dsp5 tuned, now no cruise & service trailer brake light

Don't quote me. But i think cruise won't work because it thinks it has a brake problem. I'd look at the wiring maybe something got messed up on it. Either as a safety feature, or it thinks it's brakes are depressed right now and it's kicking it off. Not much help lol other than the 2 problems are just 1 problem if I was to guess


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[Yellow Jacket]

Don't quote me. But i think cruise won't work because it thinks it has a brake problem. I'd look at the wiring maybe something got messed up on it. Either as a safety feature, or it thinks it's brakes are depressed right now and it's kicking it off. Not much help lol other than the 2 problems are just 1 problem if I was to guess


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Thanks, I assume they are related also, but I used the pulled OS to build the DSP5....just wasn't sure if I was missing something obvious in a tune file causing it. But lots of views and no replys, when I get the truck back I'll check out what fault is and know more...

 

[WVRigrat05]

The brake controller may not be plugged in 100%. i had mine apart to take out the brake/park switch and I got the service brake thing, I didn't have it all the way in somehow. Not sure if my cruise didn't work or not though.

 

[joshgabel]

same thing happened to me on my truck with the exception of the trailer brake issue.. replaced brake top light switch and cruise control cluster. and still no resolution. life sucks without cruise.
p0571 - finally just removed it from my current tune. still no cruise but at least the truck drives right now.

following now for resolution.

 

[Hoffie]

Does the cruise control button light up on the steering wheel? If not, check the fuse.

 

[catman3126]

I've seen this on several LMM's usually lifted and the speedo is off. is this one lifted an or is the speedo off? if there is enough of a difference between the TOS an the wheels speed sensors it will do this. something to check anyway.

 

[Novak]

2008 LMM, dsp5 tuned, now no cruise & service trailer brake light

I tuned a 2008 LMM 3500 Dually a couple weeks ago, I ran a script on the file like I do for my LMM tunes... Now customer says cruise doesn't work and Service Trailer Brakes message is displayed...



I made sure I plugged brake back in after removing panel to install dsp5 switch.



Is there something obvious I could've done in the tune? I upgraded his original OS that I read with EFILive and ran a script... So I don't have reason to believe it's an OS error... Remote Start & High Idle still work...

Mine did the same thing, I changed my tune back down to stock height tires and that didn't do it and then I changed the brake switch and then I disconnected my airdog and ran it off a fuel cell and on and on and onn. I even disassembled my brakes and cleaned my wheel speed sensors. All that to hook up to a tech 2 at a les Schwab and have it tell me I had a bad wheel speed sensor connection on my front passenger. Sensor is cleaned and plugged in? No wire is broke because my lift stretched the wires under the insulation.


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[Novak]

When you lift you gotta watch those wires. I'm only up 6" so with a stock replacement I had plenty of slack to work with but idk about anything higher than that


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[NC-smokinlmm]

Brake light switch is bad on the brake pedal...

I had to fix it on my old LMM..

 

[lutzjk913]

Brake light switch is bad on the brake pedal...

I had to fix it on my old LMM..

Yep.

Same thing happened to me.

 

[Tothemax]

The wires like to break at the connector for the brake pedal position sensor also

 

[joshgabel]

Did the OP find a fix?
Im in the same situation. replaced multiple switches, replaced sped sensors, multiple tunes.. still no cruise.