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
- Device Voltage Reference Group 1 Outputs Voltage Below Threshold

DTC B138A 07
- Device Voltage Reference Group 1 Outputs Voltage Above Threshold

Diagnostic Fault Information





Circuit/System Description

The object alarm 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 an 8 V reference and ground reference to each of the object alarm sensors. The object alarm module triggers the sensors in a sequential loop. After each sensor transmits, the object alarm 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

Conditions for Setting the DTC

B138A 03

The object alarm module detects the sensor 8 V reference circuit is less than 7.2 V.

B138A 07

The object alarm module detects the sensor 8 V reference circuit is greater than 9.2 V.

Action Taken When the DTC Sets

* The parking assist system is disabled.
* 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).

Conditions for Clearing

* The object alarm module clears the history DTC when a current DTC is not detected in 100 ignition cycles.
* The condition for the DTC is no longer present.

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 (UVC) (Object Detection Description and Operation (UVC))Object Detection Description and Operation (UD7) (Object Detection Description and Operation (UD7))
Electrical Information Reference

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

Scan Tool Reference

Programming and Relearning (Programming and Relearning) for scan tool information

Circuit/System Verification

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

Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at each of the object alarm 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 circuit tests normal, replace the object alarm module.

3. 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.

• If the DTC is set, replace the object alarm 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.