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Jeremy, Certified Truck/Bus Technician
Category: Medium and Heavy Trucks
Satisfied Customers: 2716
Experience:  ASE Med/HD Truck Technician, NATEF Diesel Engines and Electrical/Electronics Technician, EPA 608/609 HVAC Certified, Steering/Suspension and ABS/Brakes Technician
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I have a 2011 Kenworth T800, last 8 of vin, BJ294220. My

Customer Question

I have a 2011 Kenworth T800, last 8 of vin, BJ294220. My problem is the brake lights are staying on anytime the instrument cluster is awake. I am assuming it has something to do with the cecu. I have pulled brake light fuses, brake light switch connector, and instrument cluster connector. I checked that the hand brake lever isn't pulled but I'm flying blind. I need a wiring diagram or some more information. Thanks Ted Fisher
Submitted: 2 months ago.
Category: Medium and Heavy Trucks
Expert:  Jeremy replied 2 months ago.

My name is ***** ***** I will assist you with your question today.

I'm an independent contractor and I don't get paid until a rating has been made.

We can go back and forth as needed to help resolve the issue you are having. Follow ups are free after ratings, so rate in confidence!

Was the truck in the shop for any programming at all or for any computer diagnostics? Do you have the Paccar software?


You want a 5 star service and I want to provide a 5 star service. Please consider that I don't know your skill level as well as I can't see, touch, smell, hear the vehicle/machine in question. Please provide as much detail as possible and I will provide as much back.

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Customer: replied 2 months ago.
I do not have paccar software. I have the Cummins inline 5 and a prolink IQ with heavy duty standard. It has been to Kenworth a few times in the past four months, for exhaust and fuel problems. I put an injector in it about a month ago and had program the injector code. The brake light deal started about a week ago. Since then we put a radiator in it and I soldered an injector solenoid and cleared the codes. Now my only problem is the brake lights.
Expert:  Jeremy replied 2 months ago.

The brake lights power from the module. You already checked for the signal at the brake switch and had nothing you wrote so that leaves the module acting up. Sometimes the relay sticks and will signal the module to send the brake lamps. Whe nthe dash lights up, the module powers up and that is why you have the lights then.

Give that relay a check and then do a wiggle tests on the module to see that nothing is acting there. If nothing is acting there, then I would suggest having the module rest.

There is a parameter for the mine trucks to have the brake lights come on anytime the truck park brakes are set and the module powers on. That is why I asked if the truck was in the shop with any diagnostics connected for someone could have did a program to try and resolve a module error and activated that feature.

Customer: replied 2 months ago.
I have not checked the relay yet but can you send me wiring diagrams of the cab and light wiring?
Customer: replied 2 months ago.
Do you have wiring diagrams?
Expert:  Jeremy replied 2 months ago.

Not for the T800 i don't. i will opt out for someone that does.

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