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Dan, Technician
Category: Chevy
Satisfied Customers: 24468
Experience:  Independent Shop Experience, 2 Year Automotive Diploma, & Access to Information Database
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Chevrolet Silverado 1500 HD: Have an 05 5.3 green wire will

Customer Question

Have an 05 5.3 green wire will not switch to ground when commanded. Is the pcm bad?
Submitted: 2 years ago.
Category: Chevy
Expert:  Dan replied 2 years ago.
Hello, my name is ***** ***** I'm here to help get your problem solved. It does sound like PCM has failed but you didn't mention what circuit your working on or what problem is? Let me know, thanks.
Customer: replied 2 years ago.

P0480 cooling fan relay 1. Low speed won't work. The free wire commands low speed when grounded from pcm, this is not happening. I replaced the engine. Now I have this problem, so I am verifying all my grounds are connected. It didn't do this before, so hopefully something I over looked

Expert:  Dan replied 2 years ago.
These vehicles have a lot of problems with PCM connector corrosion problems. This code is related to cooling fan relay 1. I you ground dark green wire at pin 42 of connector 2 at PCM it should activate the relay. If grounding wire activates relay but you cannot activate with scan tool this would either mean poor connection or PCM has failed. Let me know how it goes or if you have more questions, thanks.
Customer: replied 2 years ago.

Pin 42 on pcm is broken off from corrosion.

Expert:  Dan replied 2 years ago.

Good to hear you found problem. Let me know if you have more questions, thanks!