× Auto Repair Pros Member Benefits TechHelp Knowledge Base Forums Resources My iATN Marketplace Chat Pricing About Us Join Industry Sponsors Video Members Only Repair Shops Auto Pro Careers Auto Pro Reviews
Join Now
International Automotive Technicians Network
2004 Avalanche Charging System - P1637
Posted to Technical Discussion Forum on 9/14/2017 39 Replies

vehicle tagged above. This should be incredibly simple, and it could be. But the GM wiring diagrams don't match the truck, and the flowchart for the DTC P1637 use circuit "names" that aren't on the wiring diagram.

Flowchart refers to "generator turn on signal circuit". Wiring diagram lists two wires "generator field duty cycle signal" (GRY) and "charge indicator control" (BRN).

There is also a THIRD wire at the connector not on the diagram. It is blue.

DTC P1637 says "Generator L circuit"

hmmmm. Pretty sure it just a bad alt, but, anyone know how the names are supposed to match the "other" names ?

I THINK "charge indicator control" = "Gen L" = "Gen turn on" after about an hour of research.

Geoff from Hawaii

39 Replies Received (View Replies)

 

car Vehicle Data

2004 Chevrolet Avalanche 1500 Z66 5.3L

Engine5.3 L
Trans4-speed Automatic (Electronic)

car Vehicle Data

2004 Chevrolet Avalanche 1500 Z66 5.3L

Engine5.3 L
Trans4-speed Automatic (Electronic)