Park Assist System B0958

thecardoc3thecardoc3 Member Posts: 5,840
edited July 2016 in General
This is already diagnosed and repaired but will shared here as an example of just what it takes to perform diagnostics on a system like this. The vehicle demonstrated is a 2008 Chevrolet Silverado HD2500 with the 6.6l diesel.
The customer reported a service park assist message on the instrument cluster and the Red LED comes on and stays on. Testing started by pulling trouble codes and the system responded with the B0958-01. Service information reports that as Sensor #1 (left rear outer) signal shorted to battery.

Part of a solid diagnostic routine requires acquiring a wiring diagram. You can do that here For the path to the schematic put in Interior and Driver Amenity for the system and Parking Aid for the sub system and you will get the O.E. schematic.

From service information, circuit/system description ;
Each object sensor is a 3-wire sensor that is both a transmitter and receiver that includes a signal circuit, a low reference circuit and an 8-volt supply voltage circuit. The object alarm module supplies 8 volts to the object sensors via the supply circuit and provides the ground. The object alarm module triggers the sensors in a sequential loop. After each sensor transmits the object alarm module uses the echo or signal return to calculate the distance and position of an object from the rear bumper.

Conditions for running the DTC
Ignition voltage between 9-16 volts
The vehicle is in REVERSE.

Conditions for setting the DTC
The object sensor signal circuit output is greater than 11.5 volts.


The owner has already replaced the sensor and that didn't fix the problem. He suspects that either the harness or the module has failed.

What would you test first and where would you perform the test?

Here is what the left rear outer sensor (in blue) and the left rear inner sensor (in red) signals looked like after the repair. The yellow trace at the bottom is the ground circuit voltage, and the green towards the top is the 8v supply.




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