DTC B138A 03: Control Module Voltage Reference Output Circuit Low Voltage
DTC B138A 07: Control Module Voltage Reference Output Circuit High Voltage
Check the 'Possible Causes' listed above. Visually inspect the related wiring harness and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector pins.
The cost to diagnose the B138A GMC code is 1.0 hour of labor. The diagnosis time and labor rates at auto repair shops vary depending on the location, make and model of the vehicle, and even the engine type. Most auto repair shops charge between $75 and $150 per hour.
The object sensors are 3-wire sensors that are used to determine the distance between the vehicle and an object of interest. The Parking Assist Control Module supplies 8 V to the object sensors via the 8 V reference circuit and provides ground via the low reference circuit. The Parking Assist Control Module triggers the sensors in a sequential loop. After each sensor transmits, the Parking Assist Control Module uses the sensor echo received through the signal circuit to calculate the distance and position of an object.
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