ABS Light and Service brake light on, truck stuck in 1st gear

[Chevy25002007]

Hello,

 

I own a 2007 Chevy 2500HD Classic, I was driving around when suddenly my ABS light came on as well as my service brake system light came on. When this happened my transmission became stuck in 1st gear in drive mode, but when I used the manual mode to shift it into 2nd it worked, also when I put the truck in reverse it stalled on me, these are a very strange group of symptoms and they’ve all started happening at once, also the speedometer stoped working as well.  I have no idea where to start with this so I’m hoping someone has a slight idea of where to start, Thank you!

[Jsdirt]

Symptoms fit a sudden loss of communication between one or many modules. Bad grounds can cause this, blown fuses,  as can bad pin fitment (too loose) in connectors. Get a good scan tool on there and see what B & U-codes are there, then do some research on those. Never hurts to do a complete visual inspection of the harness in areas of heat and vibration.

 

There's also the possibility that a module has died. The ABS one is common, especially being mounted under the vehicle in the line of fire (at least on the GMT-900 - I can't recall if your 800 series is set up this way). Scan tool will give you a general idea of where to focus your attention.

Edited December 24, 2021 by Jsdirt