How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask Juan Crespo Your Own Question
Juan Crespo
Juan Crespo, ASE Certified Technician
Category: Chevy
Satisfied Customers: 1526
Experience:  A.S.E. Master Technician, Advanced Level, Emissions - Asian, Domestic, & European
Type Your Chevy Question Here...
Juan Crespo is online now
A new question is answered every 9 seconds

I have a 2004 2500HD that first lost backup lights, then

Customer Question

I have a 2004 2500HD that first lost backup lights, then daytime running lights, PRNDL indicator, tow haul function, and the trans temp gauge stopped working. I have researched it and believe it is due to my class2 serial wiring but can't seem to figure it out. The truck has a P0700 TCM trouble code
Submitted: 1 year ago.
Category: Chevy
Expert:  Juan Crespo replied 1 year ago.

Welcome, my name is***** am a verified expert automobile technician. I, and all others like me are neither employees nor agents of Just Answer. We are independent service providers using the Site to sell our Expert knowledge to customers. I strive to provide EXCELLENT 5 STAR service, please let me know what you need from me so you’re pleased with my efforts and reward me with a Positive Rating.

Yes, there seems to be a problem with the wiring between the TCM and the Allison (code P0700 is just a request to turn on the MIL). Other than plugging in a TechII to see what's going on with the specific signals, you could disconnect both ends of the harness and give them a thorough looking over, specially the one at the Allison. Make sure everything is clean and tight - no loose or bent pins, no corrosion or dirt. While you are at it, do the same with the PRNDL switch connector - back-ups and gear indicator depend on this one. Other than that, I strongly recommend plugging in a TechII before we start replacing any components.

Please let me know if that helps.

Best Regards.