DTC B153A - Liftgate Latch Switches Malfunction
Diagnostic InstructionsDTC Descriptor
DTC B153A

Liftgate Latch Switch Signal Circuit

Symptom Byte Information:Symptom Byte List

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

Signal—Liftgate Latch Sector Switch

1

2

—

—

Signal—Liftgate Latch Pawl Switch

1

2

—

—

Signal—Liftgate Latch Ratchet Switch

1

B153A 08

—

—

Signal—Rear Closure Ajar Switch

2

B153A 08

—

—

Low Reference—A23C Liftgate Latch Assembly

—

B24A0 05

—

—

  1. Driver Information Display»Rear ClosureOpen=Always On
  2. Power Liftgate (TB5)=Disabled
Circuit/System Description

For an overview of the component/system, refer to:Liftgate Description and Operation

Circuit

Description

Signal

The control module input circuit has an internal resistance connected to 12 V.

Low Reference

Grounded through the control module.

Component

Description

A23C Liftgate Latch Assembly

The DC motor unlatches the liftgate. Once the liftgate is unlatched, a switch in the latch will close, grounding the signal circuit to the control module K39 indicating liftgate status.

K39 Liftgate Control Module

The control module K39 controls the liftgate motor function depending on inputs from a variety of sensors, switches and serial data information from other control modules.

K9 Body Control Module

The module controls various vehicle functions like lighting, central door locking, power windows, etc.

Conditions for Running the DTC

Ignition » On / Vehicle » In Service Mode

Conditions for Setting the DTC
  • Signal circuit—Liftgate Latch Sector Switch=Short to GroundFor greater than 60 s
  • Signal circuit—Liftgate Latch Pawl Switch=Short to GroundFor greater than 60 s
  • Signal circuit—Liftgate Latch Ratchet Switch=Short to GroundFor greater than 60 s
  • Signal circuit—Rear Closure Ajar Switch=Short to GroundFor greater than 60 s
Actions Taken When the DTC Sets

Power Liftgate (TB5)=Disabled

Conditions for Clearing the DTC
  • A current DTC will clear when the diagnostic runs and passes.
  • A history DTC will clear after 50 consecutive malfunction-free ignition cycles.
Diagnostic Aids

If DTC B153A is set&If the parameter value changes:Rear Closure Ajar Switch/Liftgate Latch Pawl Switch/Liftgate Latch Ratchet Switch/Liftgate Latch Sector Switch&Power Liftgate (TB5)=Malfunction

Refer to:DTC B153E - Liftgate Angle Sensor Malfunction

Reference Information

Schematic Reference

Liftgate Schematics

Connector End View Reference

Master Electrical Component List

Electrical Information ReferenceScan Tool Reference

Control Module References

Circuit/System Verification
  1. Ignition » On / Vehicle » In Service Mode
  2. Operate the component:Open the liftgate.

    Verify the scan tool parameter:

    • Body Control Module:Rear Closure Ajar Switch=Active
    • Liftgate Control Module:Liftgate Latch Pawl Switch=open
    • Liftgate Control Module:Liftgate Latch Ratchet Switch=open
    • Liftgate Control Module:Liftgate Latch Sector Switch=Inactive
    • If not the specified state

      Refer to: Circuit/System Testing

    • If the specified state
  3. Operate the component:Liftgate»Close&A23C Liftgate Latch Assembly»Latching

    Verify the scan tool parameter:

    • Body Control Module:Rear Closure Ajar Switch=Active»Inactive
    • Liftgate Control Module:Liftgate Latch Pawl Switch=open»Closed
    • Liftgate Control Module:Liftgate Latch Ratchet Switch=open»Closed
    • Liftgate Control Module:Liftgate Latch Sector Switch=Inactive»Active»Inactive
    • If the parameter value does not change

      Refer to: Circuit/System Testing

    • If the parameter value changes
  4. Operate the component:S45B Liftgate Control Switch - Interior»3/4orMaximum
  5. Perform the scan tool function:Liftgate Open/Close»open&Close

    Verify the component works as specified:

    • A23C Liftgate Latch Assembly»Unlatch
    • Power Liftgate (TB5)»open&Close
    • If the component opens and closes»Power Liftgate (TB5)
  6. All OK.
Circuit/System Testing

    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:A23C Liftgate Latch Assembly
  3. Test for less than 10 Ω between the test points:Low Reference terminal 6&Ground
    • If 10 Ω or greater
    1. Disconnect the electrical connector:K39 Liftgate Control Module
    2. Test for less than 2 Ω between the test points:Low Reference terminal 6@Component harness&Terminal 16 X1@Control module harness
      • If 2 Ω or greater » Repair the open/high resistance in the circuit.
      • If less than 2 Ω » Replace the component:K39 Liftgate Control Module
    • If less than 10 Ω
  4. Ignition » On / Vehicle » In Service Mode
  5. Verify the scan tool parameter:Body Control Module:Rear Closure Ajar Switch=Inactive
    • If not the specified state
    1. Ignition/Vehicle » Off
    2. Disconnect the electrical connector:K39 Liftgate Control Module
    3. Test for infinite resistance between the test points:Signal circuit terminal 3@Component harness&Ground
      • If less than infinite resistance » Repair the short to ground on the circuit.
      • If infinite resistance » Replace the component:K39 Liftgate Control Module
    • If the specified state
  6. Verify the scan tool parameter:Liftgate Control Module:Liftgate Latch Ratchet Switch=Closed
    • If not the specified state
    1. Ignition/Vehicle » Off
    2. Disconnect the electrical connector:K39 Liftgate Control Module
    3. Test for infinite resistance between the test points:Signal circuit terminal 5@Component harness&Ground
      • If less than infinite resistance » Repair the short to ground on the circuit.
      • If infinite resistance » Replace the component:K39 Liftgate Control Module
    • If the specified state
  7. Verify the scan tool parameter:Liftgate Control Module:Liftgate Latch Pawl Switch=Closed
    • If not the specified state
    1. Ignition/Vehicle » Off
    2. Disconnect the electrical connector:K39 Liftgate Control Module
    3. Test for infinite resistance between the test points:Signal circuit terminal 1@Component harness&Ground
      • If less than infinite resistance » Repair the short to ground on the circuit.
      • If infinite resistance » Replace the component:K39 Liftgate Control Module
    • If the specified state
  8. Verify the scan tool parameter:Liftgate Control Module:Liftgate Latch Sector Switch=Inactive
    • If not the specified state
    1. Ignition/Vehicle » Off
    2. Disconnect the electrical connector:K39 Liftgate Control Module
    3. Test for infinite resistance between the test points:Signal circuit terminal 2@Component harness&Ground
      • If less than infinite resistance » Repair the short to ground on the circuit.
      • If infinite resistance » Replace the component:K39 Liftgate Control Module
    • If the specified state
  9. Connect a 3 A fused jumper wire between the test points:Signal circuit terminal 3&Low Reference terminal 6
  10. Verify the scan tool parameter:Body Control Module:Rear Closure Ajar Switch=Active
    • If not the specified state
    1. Ignition/Vehicle » Off & Remove » Jumper wire(s)
    2. Disconnect the electrical connector:K39 Liftgate Control Module
    3. Ignition » On / Vehicle » In Service Mode
    4. Test for less than 1 V between the test points:Signal circuit terminal 3@Component harness&Ground
      • If 1 V or greater » Repair the short to voltage on the circuit.
      • If less than 1 V
    5. Ignition/Vehicle » Off
    6. Test for less than 2 Ω between the test points:Signal circuit terminal 3@Component harness&Terminal 9 X1@Control module harness
      • If 2 Ω or greater » Repair the open/high resistance in the circuit.
      • If less than 2 Ω » Replace the component:K39 Liftgate Control Module
    • If the specified state
  11. Connect a 3 A fused jumper wire between the test points:Signal circuit terminal 1&Low Reference terminal 6
  12. Verify the scan tool parameter:Liftgate Control Module:Liftgate Latch Pawl Switch=open
    • If not the specified state
    1. Ignition/Vehicle » Off & Remove » Jumper wire(s)
    2. Disconnect the electrical connector:K39 Liftgate Control Module
    3. Ignition » On / Vehicle » In Service Mode
    4. Test for less than 1 V between the test points:Signal circuit terminal 1@Component harness&Ground
      • If 1 V or greater » Repair the short to voltage on the circuit.
      • If less than 1 V
    5. Ignition/Vehicle » Off
    6. Test for less than 2 Ω between the test points:Signal circuit terminal 1@Component harness&Terminal 6 X1@Control module harness
      • If 2 Ω or greater » Repair the open/high resistance in the circuit.
      • If less than 2 Ω » Replace the component:K39 Liftgate Control Module
    • If the specified state
  13. Connect a 3 A fused jumper wire between the test points:Signal circuit terminal 5&Low Reference terminal 6
  14. Verify the scan tool parameter:Liftgate Control Module:Liftgate Latch Ratchet Switch=open
    • If not the specified state
    1. Ignition/Vehicle » Off & Remove » Jumper wire(s)
    2. Disconnect the electrical connector:K39 Liftgate Control Module
    3. Ignition » On / Vehicle » In Service Mode
    4. Test for less than 1 V between the test points:Signal circuit terminal 5@Component harness&Ground
      • If 1 V or greater » Repair the short to voltage on the circuit.
      • If less than 1 V
    5. Ignition/Vehicle » Off
    6. Test for less than 2 Ω between the test points:Signal circuit terminal 5@Component harness&Terminal 5 X1@Control module harness
      • If 2 Ω or greater » Repair the open/high resistance in the circuit.
      • If less than 2 Ω » Replace the component:K39 Liftgate Control Module
    • If the specified state
  15. Connect a 3 A fused jumper wire between the test points:Signal circuit terminal 2&Low Reference terminal 6
  16. Verify the scan tool parameter:Liftgate Control Module:Liftgate Latch Sector Switch=Active
    • If not the specified state
    1. Ignition/Vehicle » Off & Remove » Jumper wire(s)
    2. Disconnect the electrical connector:K39 Liftgate Control Module
    3. Ignition » On / Vehicle » In Service Mode
    4. Test for less than 1 V between the test points:Signal circuit terminal 2@Component harness&Ground
      • If 1 V or greater » Repair the short to voltage on the circuit.
      • If less than 1 V
    5. Ignition/Vehicle » Off
    6. Test for less than 2 Ω between the test points:Signal circuit terminal 2@Component harness&Terminal 4 X1@Control module harness
      • If 2 Ω or greater » Repair the open/high resistance in the circuit.
      • If less than 2 Ω » Replace the component:K39 Liftgate Control Module
    • If the specified state
  17. Test or replace the component:A23C Liftgate Latch Assembly
Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair:Diagnostic Repair Verification