Hello,
I have a 2005 tahoe Z71 that i just had a used engine installed on about 5 days ago. Everything seemed to be fine until today when my wife took it for a drive and as she was driving the ABS light came on followed by the brake light and then a service brake system message appears on dash. Her speedometer doesn't seem to work now and it seems like tranny wont come out of 2nd gear. I believe the tranny gets put in a safe mode when something is going on. Any help would be appreciated. I never expierienced this problem prior to the engine install. Does it sound like it could be my speed sensor?

 

Okay...... I brought the Tahoe into dealership to diagnose the problem and they have ruled out any mechanical problem, bad module or wheel speed sensor/ Vechicle speed sensor. They are leaning towards an electrical problem possibly a pinched wire or bad connection. I will let you know what I find out.

 

Well I got the tahoe repaired the other day but I wanted to wait a few days before I posted the dealerships fix just to make sure they indeed fixed it. And so far so good. The problem was electrical. Here is what Chevy did...........traced all wires from the main harness and found two schaffed wires from the output speeds sensor to rear wheel speed sensor. Repaired wires and resecured main harness. This repair fixed everything. My brake light went off, my ABS light went off, service brake system message on dash went away and my speedometer is working fine.

 

Thanks for the report back.

Did they indicate how the wires got chaffed in the first place?

 

They said probably just normal driving ended up doing it. They said there was no indication that the installation of my new engine a few days prior to expieriencing the brake/ ABS problem was the cause of the problem.