Circuit/System Testing

NOTE:

Use the schematics and connector end views to identify the device's ground, B+, ignition, and serial data circuit terminals.

Ignition/Vehicle OFF, all access doors closed, all vehicle systems OFF, and all keys at least 3 m (9.8 ft) away from vehicle. Disconnect the harness connectors at the P16 Instrument Cluster. It may take up to 10 min for all vehicle systems to power down.
Test for less than 10 Ω between each ground circuit terminal and ground.
- If 10 Ω or greater
1. Ignition/Vehicle OFF.
2. Test for less than 2 Ω in the ground circuit end to end.
  - If 2 Ω or greater, repair the open/high resistance in the circuit.
  - If less than 2 Ω, repair the open/high resistance in the ground connection.
- Go to next step: If less than 10 Ω
Ignition ON/Vehicle In Service Mode.
If equipped, verify a test lamp illuminates between each B+ circuit terminal and ground.
- If the test lamp does not illuminate and the circuit fuse is good
1. Ignition/Vehicle OFF, remove the test lamp.
2. Test for less than 2 Ω in the B+ circuit end to end.
  - If 2 Ω or greater, repair the open/high resistance in the circuit.
  - If less than 2 Ω, verify the fuse is not open and there is voltage at the fuse.
- If the test lamp does not illuminate and the circuit fuse is open
1. Ignition/Vehicle OFF, remove the test lamp.
2. Test for infinite resistance between the B+ circuit and ground.
  - If less than infinite resistance, repair the short to ground on the circuit.
  - If infinite resistance, replace the P16 Instrument Cluster.
- Go to next step: If the test lamp illuminates
If equipped, verify a test lamp illuminates between each ignition circuit terminal and ground.
- If the test lamp does not illuminate and the circuit fuse is good
1. Ignition/Vehicle OFF, remove the test lamp.
2. Test for less than 2 Ω in the ignition circuit end to end.
  - If 2 Ω or greater, repair the open/high resistance in the circuit.
  - If less than 2 Ω, verify the fuse is OK and there is voltage at the fuse.
- If the test lamp does not illuminate and the circuit fuse is open
1. Ignition/Vehicle OFF, remove the test lamp.
2. Test for infinite resistance between the ignition circuit and ground.
  - If less than infinite resistance, repair the short to ground on the circuit.
  - If infinite resistance, replace the P16 Instrument Cluster.
- Go to next step: If the test lamp illuminates
If equipped, verify a test lamp illuminates between each ignition circuit terminal, which is controlled by a control module, and ground.
- If the test lamp does not illuminate
1. Ignition/Vehicle OFF, remove the test lamp, disconnect the harness connectors at the control module that controls the ignition circuit.
2. Test for infinite resistance between the ignition circuit and ground.
  - If less than infinite resistance, repair the short to ground on the circuit.
  - Go to next step: If infinite resistance
3. Test for less than 2 Ω in the ignition circuit end to end.
  - If 2 Ω or greater, repair the open/high resistance in the circuit.
  - If less than 2 Ω, replace the control module that controls the ignition circuit.
- Go to next step: If the test lamp illuminates
Test for less than 4.5 V between each gateway isolated low speed GMLAN serial data circuit terminal and ground.
- If 4.5 V or greater
  Refer to Scan Tool Does Not Communicate with Gateway Isolated Low Speed GMLAN Device to test for a short to voltage.
- Go to next step: If less than 4.5 V
Ignition/Vehicle OFF, all access doors closed, all vehicle systems OFF, and all keys at least 3 m (9.8 ft) away from vehicle. It may take up to 10 min for all vehicle systems to power down.
Test for greater than 100 Ω between each gateway isolated low speed GMLAN serial data circuit terminal and ground.
- If 100 Ω or less
  Refer to Scan Tool Does Not Communicate with Gateway Isolated Low Speed GMLAN Device to test for a short to ground.
- Go to next step: If greater than 100 Ω
Disconnect the harness connectors at the device setting the DTC.
Test for less than 2 Ω in the gateway isolated low speed GMLAN serial data circuits end to end between the P16 Instrument Cluster and the device setting the DTC.
- If 2 Ω or greater
  Repair the open/high resistance in the serial data circuit.
- Go to next step: If less than 2 Ω
Replace the P16 Instrument Cluster.