Mike's Workshop Manuals: Service manuals for every vehicle
Home >> GMC >> 2016 >> Terrain SL, Gas >> Repair and Diagnosis >> External Pages >> Different car >> Section 16 (Lighting System) >> Diagnostic Information and Procedures >> Interior Backlighting Malfunction >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2015 GMC Terrain and 2015 Chevrolet Equinox. However, it is still accessible from the selected car via links, so may be relevant.

Dimmer Switch Malfunction

  1. Ignition OFF, disconnect the harness connector at the S36 Instrument Panel Dimmer Switch, ignition ON.
  2. Verify a test lamp illuminates between the low reference circuit terminal 1 and B+.
    • If the test lamp does not illuminate 
    1. Ignition OFF, disconnect the X1 harness connector at the K9 Body Control Module, ignition ON.
    2. Test for less than 1 V between the low reference circuit terminal 1 and ground.
      • If 1 V or greater, repair the short to voltage on the circuit.
      • If less than 1 V
    3. Test for less than 2 Ω in the low reference circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, replace the K9 Body Control Module.
    • If the test lamp illuminates 
  3. Test for B+ between the B+ circuit terminal 6 and ground.
    • If less than B+ 
    1. Ignition OFF, disconnect the X1 harness connector at the K9 Body Control Module.
    2. Test for infinite resistance between the B+ reference circuit and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • If infinite resistance
    3. Test for less than 2 Ω in the B+ reference circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, replace the K9 Body Control Module.
    • If B+ 
  4. Verify a test lamp does not illuminate between the B+ circuit terminal 6 and ground.
    • If the test lamp illuminates 
    1. Ignition OFF, disconnect the X1 harness connector at the K9 Body Control Module, ignition ON.
    2. Test for less than 1 V between the B+ circuit terminal 6 and ground.
      • If 1 V or greater, repair the short to voltage on the circuit.
      • If less than 1 V, replace the K9 Body Control Module.
    • If the test lamp does not illuminate 
  5. Verify the scan tool LED Backlight Dimming Command parameter is greater than 40%.
    • If 40% or less 
    1. Vehicle OFF, disconnect the X2 harness connector at the K9 Body Control Module, ignition ON.
    2. Test for less than 1 V between the signal circuit terminal 2 and ground.
      • If 1 V or greater, repair the short to voltage on the circuit.
      • If less than 1 V, replace the K9 Body Control Module.
    • If greater than 40% 
  6. Install a 3 A fused jumper wire between the signal circuit terminal 2 and the B+ circuit terminal 6.
  7. Verify the scan tool LED Backlight Dimming Command parameter is less than 30%.
    • If 30% or greater 
    1. Ignition OFF, disconnect the X2 harness connector at the K9 Body Control Module.
    2. Test for infinite resistance between the signal circuit and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • If infinite resistance
    3. Test for less than 2 Ω in the signal circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, replace the K9 Body Control Module.
    • If less than 30% 
  8. Test or replace the S36 Instrument Panel Dimmer Switch.

Interior Backlighting Malfunction

    NOTE:

    Each component supplied by the LED backlight dimming control circuits may need to be disconnected to isolate the short to ground. Use the schematics to identify the following:

    • Each component control and ground circuit terminals
    • Component locations on the LED backlight dimming control circuits
  1. Ignition OFF, scan tool disconnected, all doors closed, all accessories OFF, disconnect the harness connector at the component with inoperative backlighting. It may take up to 2 min for all vehicle systems to power down.
  2. Test for less than 10 Ω between the appropriate ground circuit terminal and ground.
    • If 10 Ω or greater 
    1. Ignition 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.
    • If less than 10 Ω 
  3. Connect a test lamp between the appropriate control circuit terminal and ground, ignition ON.
  4. Verify the test lamp turns ON and OFF when commanding the LED Backlight Dimming ON and OFF with a scan tool.
    • If the test lamp is always OFF 
    1. Ignition OFF, disconnect the appropriate harness connector listed below at the K9 Body Control Module.
      • X2 terminal 8
      • X7 terminal 9
    2. Test for infinite resistance between the control circuit and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • If infinite resistance
    3. Test for less than 2 Ω in the control circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, replace the K9 Body Control Module.
    • If the test lamp is always ON 
    1. Ignition OFF, disconnect the appropriate harness connector listed below at the K9 Body Control Module, ignition ON.
      • X2 terminal 8
      • X7 terminal 9
    2. Test for less than 1 V between the control circuit terminal and ground.
      • If 1 V or greater, repair the short to voltage on the circuit.
      • If less than 1 V, replace the K9 Body Control Module.
    • If the test lamp turns ON and OFF 
  5. Test or replace the component with inoperative backlighting.

Transmission Shift Lever Position Indicator Backlighting Malfunction

  1. Ignition OFF, scan tool disconnected, all doors closed, all accessories OFF, disconnect the harness connector at the P2 Transmission Shift Lever Position Indicator. It may take up to 2 min for all vehicle systems to power down.
  2. Test for less than 15 Ω between the ground circuit terminal C and ground.
    • If 15 Ω or greater 
    1. Ignition 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.
    • If less than 15 Ω 
  3. Connect a test lamp between the B+ circuit terminal A and ground.
  4. Verify the test lamp turns ON and OFF while turning the ignition switch ON and OFF.
    • If the test lamp is always OFF 
    1. Ignition OFF.
    2. Test for infinite resistance between the control circuit and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • If infinite resistance
    3. Test for less than 2 Ω in the control circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, replace the X51A Fuse Block - Instrument Panel.
    • If the test lamp is always ON 
    1. Ignition OFF, remove the F25DA fuse at the X51A Fuse Block - Instrument Panel, ignition ON.
    2. Test for less than 1 V between the B+ circuit terminal and ground.
      • If 1 V or greater, repair the short to voltage on the circuit.
      • If less than 1 V, replace the X51A Fuse Block - Instrument Panel.
    • If the test lamp turns ON and OFF 
  5. Test or replace the P2 Transmission Shift Lever Position Indicator.

Passenger Air Bag Disable Indicator Backlighting Malfunction

  1. Ignition OFF, scan tool disconnected, all doors closed, all accessories OFF, disconnect the harness connector at the P14 Passenger Air Bag Disable Indicator. It may take up to 2 min for all vehicle systems to power down.
  2. Test for less than 10 Ω between the ground circuit terminal 2 and ground.
    • If 10 Ω or greater 
    1. Ignition 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.
    • If less than 10 Ω 
  3. Connect a test lamp between the control circuit terminal 4 and ground, ignition ON.
  4. Verify the test lamp turns ON and OFF while turning the ignition switch ON and OFF.
    • If the test lamp is always OFF 
    1. Ignition OFF.
    2. Test for infinite resistance between the control circuit and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • If infinite resistance
    3. Test for less than 2 Ω in the control circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
    • If the test lamp is always ON 
    1. Ignition OFF, remove the F45UA fuse at the X50A Fuse Block - Underhood, ignition ON.
    2. Test for less than 1 V between the control circuit terminal and ground.
      • If 1 V or greater, repair the short to voltage on the circuit.
      • If less than 1 V, replace the X50A Fuse Block - Underhood.
    • If the test lamp turns ON and OFF 
  5. Test or replace the P14 Passenger Air Bag Disable Indicator.
scientia non olet · About Mike's Workshop Manuals