For 1990-2009 cars

### 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,

--

B096C 06,

B096D 06,

--

B138A 03

B0954 06,

B0955 06,

B0956 06,

B0957 06

--

B0958 06,

B0959 06,

B0960 06,

B0961 06,

--

B096C 06,

B096D 06

B0954 06,

B0955 06,

B0956 06,

B0957 06

--

B0958 06,

B0959 06,

B0960 06,

B0961 06,

--

B096C 06,

B096D 06,

--

B138A 07

--

Left Front Object Sensor Signal | B0954 06 | B0954 06 | B0954 01 | B0954 08, B0954 21
Left Middle Front Object Sensor Signal | B0955 06 | B0955 06 | B0955 01 | B0955 08, B0955 21
Right Middle Front Object Sensor Signal | B0956 06 | B0956 06 | B0956 01 | B0956 08, B0956 21
Right Front Object Sensor Signal | B0957 06 | B0957 06 | B0957 01 | B0957 08, B0957 21
Left Rear Object Sensor Signal | B0958 06 | B0958 06 | B0958 01 | B0958 08, B0958 21
Left Middle Rear Object Sensor Signal | B0959 06 | B0959 06 | B0959 01 | B0959 08, B0959 21
Right Middle Rear Object Sensor Signal | B0960 06 | B0960 06 | B0960 01 | B0960 08, B0960 21
Right Rear Object Sensor Signal | B0961 06 | B0961 06 | B0961 01 | B0961 08, B0961 21
Left Side Object Sensor Signal | B096C 06 | B096C 06 | B096C 01 | B096C 08, B096C 21
Right Side Object Sensor Signal | B096D 06 | B096D 06 | B096D 01 | B096D 08, B096D 21
Low Reference | -- | B0954 06, B0955 06, B0956 06, B0957 06 --

B0958 06,

B0959 06,

B0960 06,

B0961 06,

--

B096C 06,

B096D 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 object alarm module supplies 8 V to the object sensors via the 8 V 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 though 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 object alarm module has detected the 8 V reference circuit is less than 7.2 V.

#### B138A 07

The object alarm 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 parking assist indicator in the instrument panel cluster will be activated.

### 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

#### 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 of the object sensors.
2. Ignition ON, activate the park assist, test for 7.5-9.0 V between B78G Object Alarm Sensor - Left Rear Outer the 8 V reference circuit terminal 1 and ground.

⇒ | If less than the specified range, test the 8 V reference circuit for a short to ground. If the circuit tests normal, replace the K41 Object Alarm 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 K41 Object Alarm Module.

3. Connect each object sensor one at a time while monitoring the scan tool Park Assist Sensor Reference Voltage parameter. The parameter should be 7.2-9.2 V.

⇒ | If not within the specified range, replace the appropriate object alarm sensor..

4. If all circuits test normal, replace the K41 Object Alarm Module.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Front Object Alarm Sensor Replacement

• | Rear Object Sensor Replacement

• | Link X to Side Object Sensor Left Replacement

• | Link X to Side Object Sensor Right Replacement

• | Control Module References for Object Alarm Module replacement, setup and programming