AutoCodes – GMC – B1591 GMC

B1591 GMC Code - Mirror Vertical Position Sensor Voltage

Quick Answer

The Left Mirror and the Right Mirror Vertical Position Sensors are Potentiometers. Common causes include Faulty Left Mirror or Right Mirror, Left Mirror or Right Mirror harness is open or shorted, Left Mirror or Right Mirror 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
B1591 GMC indicates Mirror Vertical Position Sensor Voltage.
Common causes
Common causes include Faulty Left Mirror or Right Mirror, Left Mirror or Right Mirror harness is open or shorted, Left Mirror or Right Mirror 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 983
How popular is this code, among other codes? Low
Table of contents Created and updated by William Orellana on May 19, 2019
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Code B1591 GMC Description

The Left Mirror and the Right Mirror Vertical Position Sensors are Potentiometers. The Driver Door Module (DDM) and the Passenger Door Module (PFDM) determine the vertical position of the mirrors based on the signal voltage from these sensors. The code will be set when the signal voltage of the mirror vertical position sensor is above or below the range limits, within 10%, for 30 seconds in the requested position. The voltage range limits depend upon what the actual voltage of the 5 volt reference circuit is, and will vary from vehicle to vehicle and from module to module.
OBDII Code B1591 GMC - Mirror Vertical Position Sensor Voltage - AutoCodes.com
B1591 GMC Code - Mirror Vertical Position Sensor Voltage

What are the Possible Causes of the DTC B1591 GMC?

  • Faulty Left Mirror or Right Mirror
  • Left Mirror or Right Mirror harness is open or shorted
  • Left Mirror or Right Mirror circuit poor electrical connection

How to Fix the DTC B1591 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 is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the B1591 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.

Need more information about the B1591 GMC code?

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Need Help with the Code?

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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.

Frequently Asked Questions about B1591 GMC Code

1. What are the common symptoms of OBDII code B1591 GMC (Mirror Vertical Position Sensor Voltage)?

The common symptoms include erratic or incorrect movement of the mirrors, mirrors not adjusting properly, and the mirror control not responding.

2. What causes OBDII code B1591 GMC to trigger?

This code is typically triggered by a malfunction in the mirror vertical position sensor or issues with the sensor's voltage readings.

3. How can I diagnose the issue related to OBDII code B1591 GMC?

Diagnosing the issue involves checking the mirror vertical position sensor for any damage, testing its voltage readings, and inspecting the mirror adjustment system for faults.

4. Can a faulty mirror vertical position sensor be repaired, or does it need to be replaced?

In most cases, a faulty mirror vertical position sensor will need to be replaced to resolve the issue and clear the OBDII code B1591 GMC.

5. Are there any DIY repair tips for fixing OBDII code B1591 GMC?

DIY repair tips include checking the sensor's wiring for any loose connections, ensuring the sensor is properly calibrated, and consulting the vehicle's repair manual for specific guidelines.

6. Is it safe to continue driving with OBDII code B1591 GMC triggered?

While the vehicle may still be operable with this code triggered, it is not recommended to ignore the issue as it can affect the functionality of the mirror adjustment system.

7. Can resetting the OBDII code B1591 GMC resolve the issue temporarily?

Resetting the code may temporarily clear the warning light, but if the underlying issue with the mirror vertical position sensor is not addressed, the code is likely to reappear.

8. How much does it cost to repair OBDII code B1591 GMC at a professional auto repair shop?

The cost of repairing this code can vary depending on the extent of the issue, but it typically involves the cost of the replacement sensor and labor charges for installation.

9. Will OBDII code B1591 GMC affect the vehicle's overall performance?

While this code is related to the mirror adjustment system, it does not directly impact the vehicle's overall performance, but it can affect convenience and safety features.

10. Can a scan tool be used to troubleshoot OBDII code B1591 GMC?

Yes, a scan tool can be used to retrieve the code, monitor the sensor's voltage readings, and clear the code after the repair is completed.

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