Circuit/System Testing

WARNING: This page is about a different car, the 2005 Pontiac Pursuit and 2005 Chevrolet Cobalt. However, it is still accessible from the selected car via links, so may be relevant.

NOTE: Use the schematic to identify the following:

Control modules the vehicle is equipped with
Control module locations on the low and high speed GMLAN serial data circuits
The control module's ground, B+, ignition, and serial data circuit terminals

Using the DTC Descriptor above, determine the control module that is not communicating and should be tested.
Ignition OFF, disconnect the harness connector of the control module that is not communicating.
Test for less than 10 E between each ground circuit terminal and ground.
If greater than the specified range, test the ground circuit for an open/high resistance.
If equipped, ignition ON, verify that a test lamp illuminates between each B+ circuit terminal and ground.
If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit fuse is open, test the control circuits of the control module for a short to ground. If the circuits test normal, replace the control module.
If equipped, ignition ON, verify that a test lamp illuminates between each ignition circuit terminal and ground.
Ignition OFF for 60 seconds, test for less than 5 E between the serial data circuit terminals and the appropriate data link connector (DLC) terminal listed below:
- Class 2 serial data. circuit terminal 2
- Low speed GMLAN serial data terminal 1
- High speed GMLAN serial data terminal 6 or 14
If greater than the specified range, test the serial data circuit for an open/high resistance between the non-communicating control module and the control module setting the DTC or a serial data splice pack.
If all circuits test normal, replace the control module that is not communicating.