AutoCodes – GMC – B320B GMC

B320B GMC Code - Rear Door Window Motor

Quick Answer

The front door, rear door and middle door power window motors communicate with the Drivers Door Module (DDM), Passenger Door Module (PDM) and Rear Door Modules and Middle Door Modules over the LIN BUS. Common causes include Faulty Rear Door Window Motor, Rear Door Window Motor harness is open or shorted, Rear Door Window Motor circuit poor electrical connection. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means: B320B GMC indicates Rear Door Window Motor.
Common causes: Common causes include Faulty Rear Door Window Motor, Rear Door Window Motor harness is open or shorted, Rear Door Window Motor circuit poor electrical connection.
Severity: High - diagnose this code as soon as possible.
Can I drive?: Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

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Code Popularity 755

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

What is this?

Table of contents Created and updated by William Orellana on Mar 05, 2020

Description
Possible Causes
How To Fix
Tech Notes
Cost to Diagnose
Comments
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Code B320B GMC Description

The front door, rear door and middle door power window motors communicate with the Drivers Door Module (DDM), Passenger Door Module (PDM) and Rear Door Modules and Middle Door Modules over the LIN BUS. The motors contain a logic module which must be normalized or programmed any time the window motor is serviced to provide proper operation and communication between door modules and window motors. The Diagnostic Trouble Code (DTC) sets when an internal malfunction has been detected by the DDM or PDM in the Front Door, Rear Door, or Middle Door window motor while commanding the window motor UP/DOWN.

OBDII Code B320B GMC - Rear Door Window Motor - AutoCodes.com — B320B GMC Code - Rear Door Window Motor

What does this mean?

What are the Possible Causes of the DTC B320B GMC?

Faulty Rear Door Window Motor
Rear Door Window Motor harness is open or shorted
Rear Door Window Motor circuit poor electrical connection
Faulty Rear Door Module

How to Fix the DTC B320B GMC?

Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.

What does this mean?

Code Tech Notes

B320B 39 Rear Door Window Motor Internal Electronic Failure/Discard
B320B 42 Rear Door Window Motor Calibration Data Set Not Programmed
B320B 4B Rear Door Window Motor Calibration Not Learned

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the B320B GMC code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

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About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.