Circuit/System Testing
NOTE:
Use the schematic to identify the following:
- Control modules the vehicle is equipped with
- Control module locations on the class 2 serial data circuit
- The control modules B+, ignition, and ground
- Determine the module that is not communicating. Refer to Control Module U Code List .
- Ignition OFF, disconnect the necessary harness connector of the module that is not communicating.
- Test for less than 5 Ω between each ground circuit terminal and ground.
- If greater than the specified range, test the ground circuit for an open/high resistance.
- If equipped, 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.
- If the test lamp does not illuminate, test the ignition 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.
- Ignition OFF for 60 seconds, test for less than 5 Ω between the serial data circuit terminals and the DLC terminal class 2 serial data terminal 2
- If greater than the specified range, test the serial data circuit for an open/high resistance between the non communicating control module and a module setting the DTC or a serial data splice pack.
- If all circuits test normal, replace the control module that is not communicating.