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DTC B138A

Diagnostic Instructions

    • Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
    • Review Strategy Based Diagnosis for an overview of the diagnostic approach.
    • Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptors

DTC B138A 03: Control Module Voltage Reference Output Circuit Low Voltage

DTC B138A 07: Control Module Voltage Reference Output Circuit High Voltage

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

8 V Reference

B0954 06, B0955 06, B0956 06, B0957 06, B0958 06, B0959 06, B0960 06, B0961 06, B138A 03

B0954 06, B0955 06, B0956 06, B0957 06, B0958 06, B0959 06, B0960 06, B0961 06,

B0954 06, B0955 06, B0956 06, B0957 06, B0958 06, B0959 06, B0960 06, B0961 06, B138A 07

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Front Object Sensor - Left Outer Signal

B0954 06

B0954 06

B0954 01

B0954 08, B0954 21

Front Object Sensor - Left Middle Signal

B0955 06

B0955 06

B0955 01

B0955 08, B0955 21

Front Object Sensor - Right Middle Signal

B0956 06

B0956 06

B0956 01

B0956 08, B0956 21

Front Object Sensor - Right Outer Signal

B0957 06

B0957 06

B0957 01

B0957 08, B0957 21

Rear Object Sensor - Left Outer Signal

B0958 06

B0958 06

B0958 01

B0958 08, B0958 21

Rear Object Sensor - Left Middle Signal

B0959 06

B0959 06

B0959 01

B0959 08, B0959 21

Rear Object Sensor - Right Middle Signal

B0960 06

B0960 06

B0960 01

B0960 08, B0960 21

Rear Object Sensor - Right Outer Signal

B0961 06

B0961 06

B0961 01

B0961 08, B0961 21

Low Reference

--

B0954 06, B0955 06, B0956 06, B0957 06, B0958 06, B0959 06, B0960 06, B0961 06

--

--

Circuit/System Description

The object sensors are 3-wire sensors that are used to determine the distance between the vehicle and an object of interest. The parking assist control module supplies 8 V to the object sensors via the 8 V reference circuit and provides ground via the low reference circuit. The parking assist control module triggers the sensors in a sequential loop. After each sensor transmits, the parking assist control module uses the sensor echo received through the signal circuit to calculate the distance and position of an object.

Conditions for Running the DTC

    • Ignition ON
    • The parking assist is activated. The activation takes place through putting in the reverse gear or through operating the parking assist switch.

Conditions for Setting the DTC

B138A 03

The advance parking assist control module has detected the 8 V reference circuit is less than 7.2 V.

B138A 07

The advance parking assist control module has detected the 8 V reference circuit is greater than 9.2 V.

Action Taken When the DTC Sets

    • The parking assist is disabled.
    • The cluster displays service park assist symbol.

Conditions for Clearing the DTC

The condition for setting the DTC is no longer present.

Reference Information

Schematic Reference

Object Detection Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Object Detection Description and Operation : C140/Long Body UFR or UD7 → C145/Short Body UFR → Rear Vision Camera → Holden Genuine Accessory(Aftermarket)

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

Ignition ON, activate the parking assist, observe the scan tool Park Assist Sensor Reference Voltage parameter. The reading should be between 7.2-9.2 V.

Circuit/System Testing

  1. Ignition OFF, disconnect the harness connector at each B78 rear object sensors.
  2. Ignition ON, activate the park assist, test for 7.5-9.0 V between the 8 V reference circuit terminal 1 at the B78G Rear Object Sensor - Left Outer harness connector and ground.
  3. If less than the specified range, test the 8 V reference circuit for a short to ground. If the circuit tests normal, replace the K86 advance parking assist control module.
    If greater than the specified range, test the 8 V reference circuit for a short to voltage. If the circuit tests normal, replace the K86 advance parking assist control module.
  4. Install each object alarm sensor harness connector one at a time, checking DTCs after each sensor is connected. Verify DTC B138A is not set as current.
  5. If the DTC is set, replace the object alarm sensor that was connected immediately before the DTC set.
  6. Repeat steps 1 through 3 for B78 front object sensors.
  7. If all circuits test normal, replace the K86 advance parking assist control module.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Front and Rear Object Alarm Module Replacement : With UFR → With UFR and UD7
    •  Rear Parking Assist Alarm Sensor Replacement : Short Body → Long Body
    • Control Module References for advance parking assist control module replacement, programming and setup
   


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