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Home >> Cadillac >> 2019 >> CTS Base, RWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 68 (Automatic Transmission - 8L45 (M5N) Or 8L90 (M5U) - Diagnostic Information And Procedures) >> Diagnostic Information and Procedures >> DTC P0815, P0816, P0826-P0828, or P085F - Manual Mode or Tap Up/Tap Down Switch Malfunction >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2018 Cadillac CTS. However, it is still accessible from the selected car via links, so may be relevant.

Test 1

    NOTE:

    It may take up to 2 min for all vehicle systems to power down before an accurate ground or low reference circuit continuity test can be performed.

  1. Ignition/Vehicle & All vehicle systems - Off
  2. Disconnect the electrical connector: S3 Transmission Shift Lever
  3. Test for less than 10 ohms between the test points: Ground circuit terminal 2 & Ground
    • If 10 ohms or greater 
    1. Ignition/Vehicle - Off
    2. Test for less than 2 ohms between the test points: Ground circuit terminal 2@Component harness & The other end of the circuit
      • 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 less than 10 ohms 
  4. Ignition - On / Vehicle - In Service Mode
  5. Verify the scan tool parameter: Driver Shift Control Mode Switch @ K9 Body Control Module = Inactive
    • If not the specified state 
    1. Ignition/Vehicle - Off
    2. Disconnect the electrical connector: X2 @ K9 Body Control Module
    3. Test for infinite resistance between the test points: Signal circuit terminal 11 @Control module harness & Ground
      • If less than infinite resistance - Repair the short to ground on the circuit.
      • If infinite resistance - Replace the component: K9 Body Control Module
    • Go to next step: If the specified state 
  6. Connect a 3 A fused jumper wire between the test points: Signal circuit terminal 3 @Component harness & Ground circuit terminal 2
  7. Verify the scan tool parameter: Driver Shift Control Mode Switch = Invalid
    • If not the specified state 
    1. Ignition/Vehicle - Off & Remove - Jumper wire(s)
    2. Disconnect the electrical connector: X2 @K9 Body Control Module
    3. Ignition - On / Vehicle - In Service Mode
    4. Test for less than 1 V between the test points: Signal circuit terminal 11 @ Control module harness & Ground
      • If 1 V or greater - Repair the short to voltage on the circuit.
      • Go to next step: If less than 1 V
    5. Ignition/Vehicle - Off
    6. Test for less than 2 ohms between the test points: Signal circuit terminal 3@Component harness & The other end of the circuit Park/Neutral Position Switch
      • 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 the specified state 
  8. Test or replace the component: S3 Transmission Shift Lever

Test 2

    NOTE:

    It may take up to 2 min for all vehicle systems to power down before an accurate ground or low reference circuit continuity test can be performed.

  2. Ignition/Vehicle - Off
  3. Disconnect the component: S2R Transmission Manual Shift Switch - Right
  4. Test for less than 5 ohms between the test points: Ground circuit terminal 2 & Ground
    • If 5 ohms or greater 
    1. Ignition/Vehicle - Off
    2. Test for less than 2 ohms between the test points: Ground circuit terminal 2 & The other end of the circuit
      • 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 less than 5 ohms 
  5. Ignition/Vehicle - On
  6. Test for 11.6 to 12.4 V between the test points: Signal circuit terminal 1 & Ground
    • If not between 11.6 and 12.4 V 
    1. Ignition/Vehicle - Off
    2. Disconnect the appropriate electrical connector: K9 Body Control Module
    3. Test for infinite resistance between the test points: Signal circuit terminal 1 & Ground
      • If less than infinite resistance - Repair the short to ground on the circuit.
      • Go to next step: If infinite resistance
    4. Test for less than 2 ohms between the test points: Signal circuit terminal 1 & The other end of the circuit
      • 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 between 11.6 and 12.4 V 
  7. Ignition/Vehicle - Off
  8. Disconnect the component: S2L Transmission Manual Shift Switch - Left
  9. Test for less than 2 ohms between the test points: Signal circuit terminal 2@S2L Transmission Manual Shift Switch - Left & Signal circuit terminal 3@S2R Transmission Manual Shift Switch - Right
    • If 2 ohms or greater 

      Repair the open/high resistance in the circuit.

    • Go to next step: If less than 2 ohms 
  10. Test for less than 5 ohms between the test points: Ground circuit terminal 1@S2L Transmission Manual Shift Switch - Left & Ground
    • If 5 ohms or greater 
    1. Ignition/Vehicle - Off
    2. Test for less than 2 ohms between the test points: Ground circuit terminal 1 & The other end of the circuit
      • 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 less than 5 ohms 
  11. Test or replace the component:
    • S2R Transmission Manual Shift Switch - Right
    • S2L Transmission Manual Shift Switch - Left
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