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Home >> Cadillac >> 2018 >> Escalade Base, 4WD >> Repair and Diagnosis >> External Pages >> Different car >> Section 21 (Automatic Transmission - 8L90 (M5U) - Diagnostic Information And Procedures) >> Diagnostic Information And Procedures >> DTC P1824, P182D, P18B8, P18BD, Or P18C2: Internal Mode Switch P Circuit >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2018 Chevrolet Suburban 3500 HD. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition Off and all vehicle systems Off. Disconnect the X175 harness connector at the T12 Automatic Transmission Assembly. It may take up to 2 min for all vehicle systems to power down, ignition On.
  2. Test for 8.3 - 9.3 V between the 9 V reference 1 circuit terminal 31 and ground.
    • If less than 8.3 V 
    1. Ignition Off, disconnect the harness connector at the K71 Transmission Control Module, ignition On.
    2. Test for infinite resistance between the 9 V reference 1 circuit terminal 31 and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • If infinite resistance
    3. Test for less than 1 Ω in the 9 V reference 1 circuit end to end.
      • If 1 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 1 Ω, replace the K71 Transmission Control Module.
    • If greater than 9.3 V 
    1. Ignition Off.
    2. Disconnect the harness connector at the K71 Transmission Control Module, ignition On.
    3. Test for less than 1 V between the 9 V reference 1 circuit terminal 31 and ground.
      • If greater than the specified value, repair the short to voltage on the circuit.
      • If less than the specified value, replace the K71 Transmission Control Module.
    • Go to next step: If between 8.3 - 9.3 V 
  3. Ignition Off.
  4. Using the J-35616  terminal test kit, connect a 3 A fused jumper wire from the 9 V reference 1 circuit terminal 31, to the internal mode switch P signal circuit, terminal 23 at the X175 transmission connector, ignition On.
  5. Verify with a scan tool the internal mode switch P signal circuit parameter displays 4.8 - 5.2 V.
    • If greater than 5.2 V 
    1. Ignition Off, disconnect the harness connector at the K71 Transmission Control Module, ignition On.
    2. Test for less than 1 V between the internal mode switch P signal circuit, terminal 23 and ground.
      • If greater than the specified value, repair the short to voltage on the circuit.
      • If less than the specified value, replace the K71 Transmission Control Module.
    • If less than 4.8 V 
    1. Ignition Off, disconnect the harness connector at the K71 Transmission Control Module.
    2. Test for infinite resistance between the internal mode switch P signal circuit terminal 23 and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • If infinite resistance
    3. Test for less than 1 Ω in the internal mode switch P signal circuit end to end.
      • If 1 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 1 Ω, replace the K71 Transmission Control Module.
    4. Test for infinite resistance between the internal mode switch P signal circuit and the internal mode switch A/B/C/S signal circuits, at the X175 harness connector.
      • If less than infinite resistance on any circuit, repair the short between the 2 or more IMS signal circuits.
      • If infinite resistance, replace the K71 Transmission Control Module.
    • Go to next step: If between 4.8 - 5.2 V 
  6. Perform the Component Testing.
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