B138A

DTC B138A

Diagnostic Instructions

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

DTC Descriptors
DTC B138A 03
- Sensor Power Circuit Voltage Below Threshold

DTC B138A 07
- Sensor Power Circuit Voltage Above Threshold

Diagnostic Fault Information





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 object alarm module supplies 8 volts to the object sensors via the 8 volt reference circuit and provides ground via the low reference circuit. The object alarm module triggers the sensors in a sequential loop. After each sensor transmits, the object alarm module uses the sensor ring received through the signal circuit to calculate the distance and position of an object.

Conditions for Running the DTC

* DTC B1325 is not set
* Ignition voltage is between 9 - 16 V
* The vehicle is in REVERSE

Conditions for Setting the DTC

B138A 03

The object alarm module has detected the 8-volt reference circuit is less than 7.2 V.

B138A 07

The object alarm module has detected the 8-volt reference circuit is greater than 9.2 V.

Action Taken When the DTC Sets

* Parking assist is disabled.
* The object alarm module commands the red indicator ON.
* The object alarm module sends a serial data message to the instrument panel cluster (IPC) to display SERVICE PARK ASSIST message in the driver information center (DIC) and a chime will sound.

Conditions for Clearing

* The DTC will transition to history when the fault is no longer present.
* A history DTC will clear after 100 malfunction-free ignition cycles.

Reference Information
Schematic Reference

Object Detection Schematics ([1][2]Collision Avoidance and Parking Assist Systems)
Connector End View Reference

Component Connector End Views (Connector Views)
Description and Operation

Object Detection Description and Operation (UFL) (Object Detection Description and Operation (UFL))Object Detection Description and Operation (UFR) (Object Detection Description and Operation (UFR))Object Detection Description and Operation (UFT) (Object Detection Description and Operation (UFT))
Electrical Information Reference

* Circuit Testing (Circuit Testing)
* Connector Repairs (Connector Repairs)
* Testing for Intermittent Conditions and Poor Connections (Testing For Intermittent Conditions and Poor Connections)
* Wiring Repairs (Wiring Repairs)

Scan Tool Reference

Control Module References (Programming and Relearning)for scan tool information

Circuit/System Verification

Ignition ON, transmission in REVERSE, verify that the scan tool Sensor Voltage Feed Output parameter is 7.2 - 9.2 V.

Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at each of the object sensors.
2. Ignition ON, verify DTC B138A is not set as current.

• If the DTC is set, test the 8 V reference circuit terminal 1 for a short to voltage, short to ground, or an open/high resistance. If the circuit tests normal, replace the object alarm module.

3. Install each sensor harness connector one at a time, checking DTCs after each sensor is connected. Verify DTC B138A is not set as current.

• If the DTC is set, replace the object sensor that was connected immediately before the DTC set.

Repair Instructions

Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.

* Rear Object Sensor Replacement (Rear Object Sensor Replacement)
* Control Module References (Programming and Relearning)for object alarm module replacement, setup, and programming.