B3387 – Right Front Window Up Switch Circuit Low

System: Body | Standard: ISO/SAE Controlled | Fault type: Circuit Low

Official meaning: Right Front Window Up Switch Circuit Low

Definition source: SAE J2012 naming/structure guidance

What Does B3387 Mean?

B3387 – Right Front Window Up Switch Circuit Low is an ISO/SAE controlled Body-system diagnostic trouble code that indicates the vehicle has detected a circuit low condition in the electrical circuit used for the right front window UP switch input. In other words, the control module is seeing the UP-switch signal voltage (or the interpreted input state) lower than the expected range for the current operating conditions.

This code is specific to the right front window UP switch circuit and the fault type is Circuit Low. It does not, by itself, prove a specific component has failed. The correct repair depends on confirming whether the low condition is caused by wiring damage, poor terminal connection, a short to ground, a power/ground reference issue, or a problem in the switch or the module input.

Quick Reference

• Code: B3387
• Official Title: B3387 – Right Front Window Up Switch Circuit Low
• Official Meaning: Right Front Window Up Switch Circuit Low
• System: Body
• Standard classification: ISO/SAE Controlled
• Fault type: Circuit Low
• What it indicates: The UP-switch input for the right front window is reading lower than expected
• Likely area to inspect first: Right front door switch/connector and the door-jamb harness where it flexes

Symptoms

• Right front window will not go up: pressing the right front window switch to UP produces no movement.
• Intermittent right front window UP operation: the window may raise only sometimes or require repeated presses.
• Auto/one-touch UP inoperative (if equipped): the window may not initiate one-touch UP or may cancel.
• Different behavior between switches: the right front window may respond from one control location but not another (depending on the vehicle’s switch architecture).
• DTC stored: B3387 may be stored as current or history in the Body/door module.

Common Causes

• Short to ground on the right front window UP switch signal circuit (direct contact to ground or insulation damage pulling the circuit low).
• Damaged wiring in the right front door harness, especially in the door-jamb/hinge-area flex point (broken conductor, chafed insulation, pinched harness).
• Loose, backed-out, spread, or corroded terminals at the right front window switch connector or the related module connector causing an abnormal low signal.
• Water intrusion or moisture contamination at the switch panel, connectors, or module location creating leakage paths that lower the signal.
• Insufficient power supply or poor ground reference affecting the switch circuit’s expected voltage levels (open/high resistance in a feed or ground path).
• Faulty right front window switch assembly that does not produce the correct electrical state when commanded (confirm by testing before replacement).
• Module input concern (body/door controller input circuit not interpreting the switch input correctly), to be considered only after the circuit is verified.

Diagnosis Steps

Use the correct wiring diagram for the exact vehicle configuration, a scan tool that can access Body/door module data, and a digital multimeter. The goal is to prove why the UP-switch circuit is low: short-to-ground, open/high resistance, poor terminal contact, missing feed/ground reference, or a switch/module issue.

1. Confirm the code and its status. Check whether B3387 is current or history. Record any available event data, then clear codes and attempt to operate the right front window UP function to see if B3387 resets.
2. Verify the exact symptom. Determine whether the right front window fails to go up from the right front switch, from another switch location, or from all controls. Note whether the condition is constant or intermittent.
3. Perform a focused visual inspection. Inspect the right front switch panel for signs of moisture, contamination, damaged connectors, or pinched wiring. Inspect related connectors for corrosion, bent pins, or poor pin fit.
4. Inspect the door-jamb harness at the hinge/flex area. Pull back the harness boot as appropriate and look for cracked insulation, rubbed-through sections, or partially broken conductors. This area is a frequent location for opens/shorts due to repeated flexing.
5. Check relevant power and ground integrity. Using the wiring diagram, identify the power feed(s) and ground(s) that support the switch and/or door module. Verify proper voltage on the feed and perform ground integrity checks (including voltage drop testing if accessible).
6. Use scan tool data (if available). Look for a parameter such as “Right Front Window Up Switch” status. Observe whether the input changes when the switch is pressed and released. A status that remains low/inactive can support a circuit low condition but should be confirmed with electrical testing.
7. Test the UP switch signal circuit for a low condition. Back-probe the appropriate signal wire(s) at the switch connector and/or module connector as specified by the wiring diagram. Compare readings between “switch released” and “switch pressed UP.” If the circuit remains low when it should change, continue isolating the cause.
8. Check for short-to-ground. With the circuit safely de-energized as required by service information, disconnect the switch and the receiving module connector (as applicable) and test the UP switch signal circuit for unintended continuity to ground. If continuity is present when it should not be, locate the damaged section of harness or contamination path.
9. Check for opens/high resistance. If there is no short to ground, check continuity and connector pin fit for the UP switch circuit. Wiggle the harness near the door-jamb while monitoring readings to identify intermittent opens or unstable terminal contact.
10. Test the switch assembly. If wiring, power/ground reference, and connectors test correctly, test the right front window switch operation per wiring design (discrete contacts or resistive network). Replace the switch only if it fails the specified tests.
11. Evaluate the module input only after circuit verification. If correct signals are present at the module connector yet the module still reports a low input and sets B3387, follow service procedures for module connector inspection, terminal tension checks, and any required module diagnostics.

Possible Fixes

• Repair or replace damaged wiring in the right front door harness, especially in the door-jamb flex area (restore proper routing and strain relief).
• Repair a short-to-ground on the right front window UP switch signal circuit (locate and correct chafed insulation, pinched wiring, or contamination bridging to ground).
• Clean and correct connector issues (corrosion removal, terminal repair, terminal tension correction, connector reseating) at the switch and module connectors.
• Restore proper power supply and ground reference for the switch/module circuits (repair opens/high resistance at feeds, grounds, or splices as indicated by testing).
• Replace the right front window switch assembly only if testing confirms it does not provide the correct output/state.
• Address moisture intrusion affecting the switch/connector/module area (dry, clean, and correct the entry path to prevent repeat low-signal conditions).
• Repair/replace the related module only after confirming circuit integrity and verifying that the module input is at fault per approved diagnostic procedures.

Can I Still Drive With B3387?

Yes, the vehicle is typically drivable with B3387 because it is a Body system code and does not indicate an engine or braking fault. The primary impact is functional: the right front window may not raise reliably or may not respond to the UP command. If the window cannot close, the vehicle may be exposed to weather and security risks. Repair should be scheduled promptly, especially if the window is stuck partially open.

Repair Costs

Repair cost depends on whether the confirmed root cause is door-jamb wiring damage, connector corrosion, a failed window switch, or door module diagnosis time.

Last updated: March 27, 2026