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B3187 Cadillac Code - Left Rear Window Down Switch Circuit Low

Quick Answer

This Diagnostic Trouble Code (DTC) is generated by a passenger door window switch or a passenger door window switch circuit. Common causes include Faulty Left Rear Window Switch, Left Rear Window Switch harness is open or shorted, Left Rear Window Switch 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
B3187 Cadillac indicates Left Rear Window Down Switch Circuit Low.
Common causes
Common causes include Faulty Left Rear Window Switch, Left Rear Window Switch harness is open or shorted, Left Rear Window Switch 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 430
How popular is this code, among other codes? Low
What is this?
Table of contents Created and updated by William Orellana on Mar 04, 2020
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Code B3187 Cadillac Description

This Diagnostic Trouble Code (DTC) is generated by a passenger door window switch or a passenger door window switch circuit. Each passenger door window switch is mounted to the trim panel of the appropriate passenger door. The circuits and contacts of each passenger door window switch receive battery voltage and ground from the corresponding door module, i.e. Front Passenger Door Module (PDM), Left Rear Door Module (LRDM), or Right Rear Door Module (RRDM). When a passenger door window switch is operated, the switch contacts close and the associated door module interprets the flow of voltage as a specific request to move the window up or down. If conditions are correct for window operation to occur, the door module then powers the associated window motor and circuits to move the window.
OBDII Code B3187 Cadillac - Left Rear Window Down Switch Circuit Low - AutoCodes.com
B3187 Cadillac Code - Left Rear Window Down Switch Circuit Low
What does this mean?

What are the Possible Causes of the DTC B3187 Cadillac?

  • Faulty Left Rear Window Switch
  • Left Rear Window Switch harness is open or shorted
  • Left Rear Window Switch circuit poor electrical connection
  • Faulty Left Rear Door Module (LRDM)

How to Fix the DTC B3187 Cadillac?

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 B3187 Cadillac 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 B3187 Cadillac 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 B3187 Cadillac Code

1. What does the OBDII code B3187 mean on a Cadillac?

The B3187 code indicates a problem with the left rear window down switch circuit, specifically that it is reading a low voltage.

2. What are the common symptoms of the B3187 code?

Symptoms can include the left rear window not responding to switch inputs, the window being stuck in one position, or erratic window operation.

3. What causes the B3187 code in Cadillacs?

Common causes include a faulty window switch, damaged wiring or connectors in the circuit, or a malfunctioning window motor.

4. Can I still drive my Cadillac with a B3187 code?

Yes, you can still drive the vehicle, but the left rear window may not operate correctly, which could be inconvenient or pose a security risk.

5. How can I diagnose the B3187 code?

Start by visually inspecting the wiring and connectors for damage, testing the window switch for proper function, and checking for consistent voltage in the circuit.

6. What tools are needed to fix the B3187 code?

You may need a multimeter for voltage testing, a scan tool to clear the code, and basic hand tools to access and repair the switch or wiring.

7. How do I fix the B3187 code on my Cadillac?

Repairs typically involve replacing a faulty window switch, repairing damaged wiring, or replacing the window motor if it is not functioning properly.

8. Can a blown fuse cause the B3187 code?

A blown fuse is unlikely to directly cause this code, but it’s a good idea to check related fuses as they could contribute to circuit issues.

9. Is the B3187 code related to other window malfunction codes?

Yes, it could be related to other window or body control module (BCM) codes, so scanning for additional codes is recommended.

10. Do I need to reprogram the BCM after fixing the B3187 code?

In most cases, reprogramming is not required, but clearing the code with a scan tool may be necessary after repairs.

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