GM Service Manual Online
For 1990-2009 cars only

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 B0958 01: Parking Aid Rear Sensor 1 (Left Corner) Circuit-Short to Battery

DTC B0958 06: Parking Aid Rear Sensor 1 (Left Corner) Circuit-Short to Ground or Open

DTC B0958 08: Parking Aid Rear Sensor 1 (Left Corner) Circuit-Signal Invalid

DTC B0958 21: Parking Aid Rear Sensor 1 (Left Corner) Circuit-Incorrect Period

DTC B0959 01: Parking Aid Rear Sensor 2 (Left Middle) Circuit-Short to Battery

DTC B0959 06: Parking Aid Rear Sensor 2 (Left Middle) Circuit-Short to Ground or Open

DTC B0959 08: Parking Aid Rear Sensor 2 (Left Middle) Circuit-Signal Invalid

DTC B0959 21: Parking Aid Rear Sensor 2 (Left Middle) Circuit-Incorrect Period

DTC B0960 01: Parking Aid Rear Sensor 3 (Right Middle) Circuit-Short to Battery

DTC B0960 06: Parking Aid Rear Sensor 3 (Right Middle) Circuit-Short to Ground or Open

DTC B0960 08: Parking Aid Rear Sensor 3 (Right Middle) Circuit-Signal Invalid

DTC B0960 21: Parking Aid Rear Sensor 3 (Right Middle) Circuit-Incorrect Period

DTC B0961 01: Parking Aid Rear Sensor 4 (Right Corner) Circuit-Short to Battery

DTC B0961 06: Parking Aid Rear Sensor 4 (Right Corner) Circuit-Short to Ground or Open

DTC B0961 08: Parking Aid Rear Sensor 4 (Right Corner) Circuit-Signal Invalid

DTC B0961 21: Parking Aid Rear Sensor 4 (Right Corner) Circuit-Incorrect Period

Diagnostic Fault Information

Circuit

Short to Ground

Open or High Resistance

Short to Voltage

Signal Performance

Left Rear Sensor 1 Signal

B0958 06

B0958 06

B0958 01

B0958 08

B0958 21

Left Rear Sensor 1 Low Reference

--

B0958 06

B0958 01

B0958 08

B0958 21

Left Middle Rear Sensor 2 Signal

B0959 06

B0959 06

B0959 01

B0959 08

B0959 21

Left Middle Rear Sensor 2 Low Reference

--

B0959 06

B0959 01

B0959 08

B0959 21

Right Middle Rear Sensor 3 Signal

B0960 06

B0960 06

B09506 01

B0960 08

B0960 21

Right Middle Rear Sensor 3 Low Reference

--

B0960 06

B0960 01

B0960 08

B0960 21

Right Rear Sensor 4 Signal

B0961 06

B0961 06

B0961 01

B0961 08

B0961 21

Right Rear Sensor 4 Low Reference

--

B0961 06

B0961 01

B0961 08

B0961 21

Circuit/System Description

The object alarm system monitors the distance and how close a vehicle is to an object when backing up in a parking maneuver. The object alarm system will notify the driver of any objects of interest when backing up at speeds less than 8 km/h (5 mph). The distance between a vehicle and an object of interest is monitored by the 4 ultrasonic sensors located in the rear bumpers of the vehicle. The object alarm sensors receive the echo signal reflected off an object of interest while the vehicle is backing up at speeds less than 8 km/h (5 mph). The object alarm system uses visual displays and audible warnings from the radio speakers to warn the driver of an object of interest within the defined field of view. The visual display comprises of two amber and one red indicators and these indicators illuminate based on the vehicle distance to the object of interest. The object alarm sensor is a three wire sensor comprising of the supply voltage circuit, signal circuit and the low reference circuit. Power and ground is provided to the object alarm sensor via the supply voltage circuit and low reference from the object detection alarm module. The typical object alarm sensor signal voltage when the system is active is between 7.2 V-9.2 V.

Conditions for Running the DTC

Ignition voltage is between 9-16 volts.

Conditions for Setting the DTC

B0958 01, B0959 01, B0960 01, or B0961 01

The object alarm module circuit is short to battery.

B0958 06, B0959 06, B0960 06, or B0961 06

The object alarm module circuit is short to ground or open.

B0958 08, B0959 08, B0960 08, or B0961 08

The object alarm module signal circuit is invalid.

B0958 21, B0959 21, B0960 21, or B0961 21

The object alarm module has an incorrect period.

Action Taken When the DTC Sets

    • The object alarm module commands ON the information center telltale red indicator.
    • The object alarm module sends a serial data communication message to the instrument panel cluster (IPC) to display SERVICE PARK ASSIST message in the driver information center (DIC), and the chime will sound.

Conditions for Clearing the DTC

    • The DTC becomes history when the conditions for setting the DTC are no longer present.
    • The history DTC clears after 40 malfunction-free warm-up cycles.

Reference Information

Schematic Reference

Object Detection Schematics

Connector End View Reference

Object Detection Connector End Views

Electrical Information Reference

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

Circuit/System Verification

  1. Verify that DTC B1E3A is not current.
  2. If B1E3A is current, refer to DTC B1E3A .
  3. Park brake disabled, transmission in REVERSE, suitable object behind an appropriate sensor, verify that the appropriate Rear Region scan tool parameter displays a value between Zone 1 and Zone 8.

Circuit/System Testing

  1. Ignition OFF, disconnect the harness connector of the appropriate rear object sensor.
  2. Ignition OFF for 30 seconds, test for less than 5.0 ohms between the low reference circuit terminal 2 and ground.
  3. If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the object alarm module.
  4. Ignition ON, transmission in REVERSE, test for 8.0-9.0 volts between the rear object sensor supply voltage circuit terminal 1 and ground.
  5. If greater than the specified range, test the supply voltage circuit for a short to voltage. If the circuit tests normal, replace the object alarm module.
    If less than the specified range, test the supply voltage circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the object alarm module.
  6. Ignition OFF, connect the appropriate rear object sensor and disconnect X1 harness connector at the object alarm module.
  7. Ignition ON, test for less than 1.0V between signal circuit and ground of the appropriate rear object sensor listed below:
  8. • Left Rear middle object sensor signal circuit terminal 3
    • Left Rear corner object sensor signal circuit terminal 5
    • Right Rear middle object sensor signal circuit terminal 2
    • Right Rear corner object sensor signal circuit terminal 1
    If greater than the specified range, test the signal circuit for a short to voltage.
  9. Ignition OFF, test for infinite resistance between signal circuit and ground of the appropriate rear object sensor listed below:
  10. • Left Rear middle object sensor signal circuit terminal 3
    • Left Rear corner object sensor signal circuit terminal 5
    • Right Rear middle object sensor signal circuit terminal 2
    • Right Rear corner object sensor signal circuit terminal 1
    If less than the specified value, test the signal circuit for a short to ground.
  11. Test for less than 2 ohms between the sensor signal circuit terminal 3 and signal circuit of the appropriate rear object sensor listed below:
  12. • Left Rear middle object sensor signal circuit terminal 3
    • Left Rear corner object sensor signal circuit terminal 5
    • Right Rear middle object sensor signal circuit terminal 2
    • Right Rear corner object sensor signal circuit terminal 1
    If greater than the specified range, test the signal circuit for an open/high resistance.

    Important: Because the object alarm module does not update rear object sensor data when a DTC is set, the diagnostic can not determine whether the module or the sensor is causing the DTC to set.

  13. If all circuits test normal, test or replace the appropriate rear object alarm sensor and verify that the DTC does not reset.
  14. If the DTC resets, replace object alarm module.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Rear Object Sensor Replacement
    •  Control Module References for the object alarm module replacement, setup, and programming