Circuit/System Testing
WARNING: This page is about a different car, the 2021 GMC Sierra 3500 HD and 2021 GMC Sierra 2500 HD. However, it is still accessible from the selected car via links, so may be relevant.
Test 1
- Ignition/Vehicle - Off
- Disconnect the electrical connector: S70L Steering Wheel Controls Switch - Left
- Ignition - On / Vehicle - In Service Mode
- Test for greater than 11 V between the test points: Ignition circuit terminal 10 & Ground
- If 11 V or less
- Ignition/Vehicle - Off
- Disconnect the electrical connector: X3 @ K9 Body Control Module
- Test for infinite resistance between the test points: Ignition circuit terminal 10 @ Component harness & Ground
- If less than infinite resistance - Repair the short to ground on the circuit.
- Go to next step: If infinite resistance
- Test for less than 2 ohms between the test points: Ignition circuit terminal 10 @ Component harness & Terminal 4 @ Control module harness
- If 2 ohms or greater - Repair the open/high resistance in the circuit.
- If less than 2 ohms - Replace the component: K9 Body Control Module
- Go to next step: If greater than 11 V
- Ignition/Vehicle - Off
- Disconnect the electrical connector: X3 @ K9 Body Control Module
- Test for infinite resistance between the test points: Ignition circuit terminal 4 @ Component harness & Ground
- If 2 or greater
Repair the short to ground on the circuit.
- Go to next step: If less than 2 ohms
- If 2 or greater
- Connect the electrical connector: S70L Steering Wheel Controls Switch - Left
- Test for 8.4 k to 9.2 kohms between the test points: Ignition circuit terminal 4 & Signal circuit terminal 16
- If not between 8.4 k and 9.2 kohms
- Disconnect the electrical connector: S70L Steering Wheel Controls Switch - Left
- Ignition - On / Vehicle - In Service Mode
- Test for less than 1 V between the test points: Signal circuit terminal 4 @ Component harness & Ground
- If 1 V or greater - Repair the short to voltage on the circuit.
- Go to next step: If less than 1 V
- Ignition/Vehicle - Off
- Test for less than 2 ohms between the test points: Signal circuit terminal 4 @ Component harness & Terminal 16 @ Control module harness
- If 2 ohms or greater - Repair the open/high resistance in the circuit.
- If less than 2 ohms - Replace the component: S70L Steering Wheel Controls Switch - Left
- Go to next step: If between 8.4 k and 9.2 kohms
- Press and hold the switch: Forward Collision Alert Switch @ S70L Steering Wheel Controls Switch - Left
Test for 2.3 k to 2.9 kohms between the test points: Ignition circuit terminal 4 & Signal circuit terminal 16
- If not between 2.3 k and 2.9 kohms
Replace the component: S70L Steering Wheel Controls Switch - Left
- Go to next step: If between 2.3 k and 2.9 kohms
- If not between 2.3 k and 2.9 kohms
- Replace the component: K9 Body Control Module
Test 2
- Ignition/Vehicle & All vehicle systems - Off
- Disconnect the electrical connector: P43 Collision Alert Indicators
- Verify a test lamp turns On between the test points: Ground circuit terminal 4 & B+
- If the test lamp does not turn On
- Test for less than 2 ohms between the test points: Ground circuit terminal 4 & Ground terminal
- If 2 ohms or greater - Repair the open/high resistance in the circuit.
- If less than 2 ohms - Repair the open/high resistance in the ground connection.
- Go to next step: If the test lamp turns On
- Ignition - On / Vehicle - In Service Mode
- Verify a test lamp turns On between the test points: Ignition circuit terminal 1 & Ground
- If the test lamp does not turn On and the circuit fuse is OK
- Ignition/Vehicle - Off & Remove - Test lamp
- Test for less than 2 ohms between the test points: Ignition circuit terminal 1 @ P43 Collision Alert Indicators & The other end of the circuit
- If 2 ohms or greater - Repair the open/high resistance in the circuit.
- If less than 2 ohms - Verify the fuse is OK and there is voltage at the fuse.
- If the test lamp does not turn On and the circuit fuse is open
- Ignition/Vehicle - Off & Remove - Test lamp
- Test for infinite resistance between the test points: Ignition circuit terminal 1 & Ground
- If less than infinite resistance - Repair the short to ground on the circuit.
- If infinite resistance - Test or replace the component: P43 Collision Alert Indicators
- Go to next step: If the test lamp turns On
- Ignition/Vehicle - Off
- Disconnect the electrical connector: X1 @ P16 Instrument Cluster
- Ignition - On / Vehicle - In Service Mode
- Test for less than 1 V between the test points:
- Control circuit terminal 30 @ P16 Instrument Cluster & Ground
- Control circuit terminal 12 @ P16 Instrument Cluster & Ground
- If 1 V or greater
Repair the short to voltage on the circuit.
- Go to next step: If less than 1 V
- Ignition/Vehicle - Off
- Test for infinite resistance between the test points:
- Control circuit terminal 30 @ P16 Instrument Cluster & Ground
- Control circuit terminal 12 @ P16 Instrument Cluster & Ground
- If less than infinite resistance
Repair the short to ground on the circuit.
- Go to next step: If infinite resistance
- Test for less than 2 ohms between the test points:
- Control circuit terminal 30 @ P16 Instrument Cluster & Control circuit terminal 3 @ P43 Collision Alert Indicators
- Control circuit terminal 12 @ P16 Instrument Cluster & Control circuit terminal 2 @ P43 Collision Alert Indicators
- If 2 ohms or greater
Repair the open/high resistance in the circuit.
- Go to next step: If less than 2 ohms
- Replace the component: P43 Collision Alert Indicators
- Ignition - On / Vehicle - In Service Mode
- Perform the appropriate scan tool control function: All Indicators
Verify the component activates: Collision Alert - Indicators
- If the component does not work as specified
Replace the component: P16 Instrument Cluster
- Go to next step: If the component works as specified
- If the component does not work as specified
- All OK.