I have a 2004 Chevy Silverado Duramax with a 5 speed allison transmission. last Year I needed to replace the nsbu switch, and everything worked fine until approx 2 weeks ago. I thought the switch was going bad again, but I replaced it and it did not fix the problem. When i put the truck in reverse or drive I can feel it go into limp mode. Often the brake and abs light comes on. The indicator light under the park, reverse, neutral, etc sometimes goes completely blank. If I stop and start the engine
often enough, sometimes it will work like it is supposed to, and will continue to work as long as I don't shut the truck off. The next time I start it up, it may or may not work. It is getting worse, and often it malfunctions, going into limp mode or kicking out completely. Today I check the connectors for corrosion going to the tcm, but they look really nice and clean. I tried to check the wiring harness to see if I could find any shorts, etc, but have found none. I feel the problem is electronic, and I am starting to question if I have a faulty tcm. Can you give me any advice?
JA: Is it just the ABS light? Or is the brake system warning light on, too?
Customer: Sometimes both, but most often just the abs light.
JA: Are you fixing your Silverado yourself? What have you tried so far?
Customer: I have been trying myself, but I don't have a scanner to look at the codes, so I plan to meet with a friend tomorrow to see what all codes it is giving. the check engine light is on, so I'm sure it will give some readings. I didn't know if you have had any of these symptoms before to help us trouble shoot the problem.
JA: Anything else you want the mechanic to know before I connect you?
Customer: I think that those are the main things that I think of now.