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Home >> Cadillac >> 2021 >> CT4 Sport, RWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 378 (Sunroof) >> Diagnostic Information and Procedures >> Power Sunroof/Sunshade Malfunction >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2022 Cadillac CT5. However, it is still accessible from the selected car via links, so may be relevant.

Power Sunroof Malfunction

  1. Ignition/vehicle OFF, disconnect the harness connector at the K61 Sunroof Control Module
  2. Verify a test lamp illuminates between ground circuit terminals listed below and B+.
    • Ground circuit terminal 1
    • Ground circuit terminal 2
    • If the test lamp does not illuminate 
    1. Repair the open/high resistance on circuit 2350 or ground connection.
    • Go to next step: If the test lamp illuminates 
  3. Ignition ON/vehicle in service mode, verify a test lamp illuminates between B+ circuits listed below and ground.
    • B+ circuit terminal 17
    • B+ circuit terminal 18
    • If the test lamp does not illuminate and the circuit fuse is OK 
    1. Test circuit 3540 for an open/high resistance.
      • If an open/high resistance is found, repair the fault on the circuit.
      • If an open/high resistance is not found, verify there is voltage at the fuse.
    • If the test lamp does not illuminate and the circuit fuse is open 
    1. Test circuit 3540 for a short to ground.
      • If a short to ground is found, repair the fault on the circuit.
      • Go to next step: If a short to ground is not found.
    2. Replace the K61 Sunroof Control Module
    • Go to next step: If the test lamp Illuminates 
  4. Replace the K61 Sunroof Control Module

Power Sunshade Malfunction

  1. Ignition/vehicle OFF, disconnect the harness connector at the M81 Sunroof Sunshade Motor.
  2. Verify a test lamp illuminates between low reference circuit terminal 4 and B+.
    • If the test lamp does not illuminate 
    1. Test circuit 128 for an open/high resistance.
      • If an open/high resistance is found, repair the fault on the circuit.
      • Go to next step: If an open/high resistance is not found.
    2. Replace the K61 Sunroof Control Module.
    • Go to next step: If the test lamp illuminates 
  3. Ignition ON/vehicle in service mode, test for 4.8 V - 5.2 V between 5 V reference circuit terminal 1 and ground.
    • If less than 4.8 V 
    1. Test circuit 5033 for a short to ground.
      • If a short to ground is found, repair the fault on the circuit.
      • Go to next step: If a short to ground is not found.
    2. Test circuit 5033 for an open/high resistance.
      • If an open/high resistance is found, repair the fault on the circuit.
      • Go to next step: If an open/high resistance is not found.
    3. Replace the K61 Sunroof Control Module.
    • If greater than 5.2 V 
    1. Disconnect the harness connector at the K61 Sunroof Control Module.
    2. Test circuit 5033 for a short to voltage.
      • If a short to voltage is found, repair the fault on the circuit.
      • Go to next step: If a short to voltage is not found.
    3. Replace the K61 Sunroof Control Module.
    • Go to next step: If between 4.8 V - 5.2 V 
  4. Install a test lamp between control circuit terminal 3 and control circuit terminal 6.
  5. Verify the test lamp momentarily turns On and Off when pressing the sunshade switch Open and Closed.
    • If the test lamp is always Off 
    1. Test circuits listed below for a short to ground.
      • Circuit 3781
      • Circuit 3782
      • If a short to ground is found, repair the fault on the circuit.
      • Go to next step: If a short to ground is not found.
    2. Test circuits listed below for an open/high resistance.
      • Circuit 3781
      • Circuit 3782
      • If an open/high resistance is found, repair the fault on the circuit.
      • Go to next step: If an open/high resistance is not found.
    3. Replace the K61 Sunroof Control Module.
    • If the test lamp is always On 
    1. Ignition/vehicle OFF, disconnect the harness connector at the K61 Sunroof Control Module
    2. Test for less than 1 V between control circuits listed below and ground.
      • Circuit 3781
      • Circuit 3782
      • If a short to voltage is found, repair the fault on the circuit.
      • Go to next step: If a short to voltage is not found.
    3. Replace the K61 Sunroof Control Module.
    • Go to next step: If the test lamp turns On and Off 
  6. Ignition/vehicle OFF, disconnect the harness connector at the K61 Sunroof Control Module
  7. Test for less than 1 V between control circuits listed below and ground.
    • Signal circuit terminal 10
    • Signal circuit terminal 11
    • If 1 V or greater 
    1. Repair the short to voltage on appropriate circuits listed below.
      • Circuit 3781
      • Circuit 3782
    • Go to next step: If less than 1 V 
  8. Test for less than 1 V between signal circuits listed below and ground.
    • Signal circuit terminal 13
    • Signal circuit terminal 14
    • If 1 V or greater 
    1. Repair the short to voltage on appropriate circuits listed below.
      • Circuit 5124
      • Circuit 5034
    • Go to next step: If less than 1 V 
  9. Ignition/vehicle off, test for infinite resistance between signal circuits listed below and ground.
    • Signal circuit terminal 13
    • Signal circuit terminal 14
    • If less than infinite resistance 
    1. Repair the short to ground on the appropriate circuits listed below.
      • Circuit 5124
      • Circuit 5034
    • Go to next step: If infinite resistance 
  10. Test for less than 10 Ω between signal circuit terminals listed below and the other end of the circuit.
    • Signal circuit terminal 13
    • Signal circuit terminal 14
    • If 10 Ω or greater 
    1. Repair the open/high resistance on the appropriate circuits listed below.
      • Circuit 5124
      • Circuit 5034
    • Go to next step: If less than 10 Ω 
  11. Replace the M81 Sunroof Sunshade Motor.
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