B3723 – Rear Wiper Relay Drive Circuit High (BCM)

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

Definition source: SAE J2012 naming/structure guidance

What Does B3723 Mean?

B3723 – Rear Wiper Relay Drive Circuit High (BCM) is an ISO/SAE controlled body system diagnostic trouble code that indicates the Body Control Module (BCM) detected a circuit high condition on the rear wiper relay drive circuit. In other words, the BCM sees the relay control (drive) circuit voltage or signal state higher than expected for the commanded operation.

This code describes an electrical fault on the control side of the rear wiper relay circuit (the portion the BCM uses to command the relay). It does not, by itself, prove a specific component has failed. The correct interpretation is strictly: the BCM is detecting the rear wiper relay drive circuit is “high” when it should not be, based on the BCM’s internal monitoring strategy.

Quick Reference

• Code: B3723
• Official title: B3723 – Rear Wiper Relay Drive Circuit High (BCM)
• System: Body
• Standard classification: ISO/SAE Controlled
• Fault type: Circuit High
• What it indicates: The BCM detects the rear wiper relay drive (control) circuit signal is higher than expected.
• Primary area to inspect: Relay drive/control wiring, relay socket/terminals, connectors, and any source of unintended voltage on the control circuit.

Symptoms

Because B3723 is tied to the rear wiper relay command circuit, symptoms generally involve rear wiper operation. Depending on how the circuit fails and how the BCM responds, you may notice:

• Rear wiper inoperative: rear wiper does not run when commanded.
• Rear wiper runs unexpectedly: rear wiper activates without a normal command.
• Intermittent operation: rear wiper works inconsistently.
• Rear washer/wiper coordination issues: rear washer request may not match rear wiper action, depending on vehicle logic.
• Indicator or message (if equipped): a body/wiper-related warning or message may appear.
• Stored code in BCM: B3723 stored as current or history, sometimes alongside other body-related codes.

Common Causes

A circuit high fault means the relay drive circuit is being pulled or held at a higher electrical level than the BCM expects. Causes that can create that condition include:

• Short to voltage on the rear wiper relay drive circuit: unintended contact with a powered circuit or B+ feed.
• Damaged wiring: chafing, pinched harness, melted insulation, or internal conductor damage in the drive/control circuit.
• Connector/terminal problems: corrosion, water intrusion, bent pins, spread terminals, or poor terminal retention at the BCM connector, relay socket, or intermediate connectors.
• Rear wiper relay internal fault: an internal failure that backfeeds voltage into the control side (drive circuit) or alters the expected circuit state.
• Incorrect relay type installed: a relay with different terminal layout or internal suppression that changes circuit behavior.
• Fuse/relay block or power distribution issue: unintended voltage present on the drive circuit due to internal block faults or misrouting.
• Ground path issues affecting circuit bias: a ground problem that changes the control circuit’s electrical behavior and leads to a “high” reading by the BCM.
• BCM internal driver/monitoring fault: only to be considered after external circuit checks confirm the wiring and relay path are correct.

Diagnosis Steps

Use a scan tool that can access BCM codes and data, a digital multimeter, and the correct wiring information for the vehicle. The goal is to confirm when the circuit is “high,” determine whether the voltage is being introduced externally (wiring/relay/power feed), and verify the BCM command versus the measured circuit state.

1. Confirm the code and capture data: read BCM DTCs, record B3723 status (current/history), and note any additional body-related codes that may affect rear wiper control.
2. Verify the symptom: operate the rear wiper through all switch positions and any washer-related functions. Note whether the wiper is inoperative, stuck on, or intermittent.
3. Check fuses and the relay location: inspect rear wiper-related fuses and the rear wiper relay area for signs of overheating, moisture, corrosion, or terminal discoloration.
4. Inspect relay socket and terminals: look for damaged cavities, looseness, corrosion, or pushed-out terminals that could cause unintended voltage or poor control.
5. Inspect the wiring harness: trace the rear wiper relay drive/control circuit between the BCM and the relay socket (and any intermediate connectors). Pay attention to areas where the harness can flex or rub against metal edges and brackets.
6. Command the output (if supported): use scan tool output controls to command the rear wiper relay ON/OFF while observing whether B3723 resets and whether rear wiper behavior changes. Compare commanded state to actual behavior.
7. Measure the drive circuit voltage: with key ON, measure voltage at the relay drive/control terminal (or designated test point) while commanding ON and OFF. A circuit high fault typically appears as the control circuit staying higher than expected when the BCM expects it low (or within a specific range).
8. Remove the relay and re-test: with the relay removed, re-check the control circuit electrical state. If the “high” condition changes significantly, suspect relay backfeed, relay mismatch, or socket wiring issues.
9. Check for short-to-voltage: with power removed as appropriate and per safe testing procedure, test the drive/control wire for unwanted continuity to B+ or other powered circuits. Also inspect for cross-shorts to adjacent circuits in the same harness.
10. Verify BCM power and ground integrity: perform voltage drop checks on BCM grounds and verify stable BCM power feeds. Poor module power/ground can distort monitored signals and cause improper fault detection.
11. Isolate the circuit at the module when needed: if the wiring diagram supports it, disconnect the BCM connector related to the rear wiper relay drive circuit and check whether the “high” condition is present in the harness side. This helps determine whether voltage is being introduced by the harness/relay side versus originating inside the BCM.

Possible Fixes

Repairs should be based on test results that confirm why the rear wiper relay drive circuit is reading high. Depending on the root cause, fixes may include:

• Repair wiring damage: restore insulation, repair opens/shorts, and correct routing/retention to prevent future chafing or pinching.
• Service connectors/terminals: clean corrosion, address water intrusion, repair or replace damaged terminals, and ensure proper terminal tension and locking.
• Replace the rear wiper relay: if testing confirms internal fault or backfeed, or if the installed relay is incorrect for the circuit design.
• Correct power distribution issues: repair fuse/relay block faults or unintended power feeds that place voltage on the relay drive circuit.
• Correct circuit modifications: remove or rework any wiring changes that introduce unintended voltage into the relay drive/control circuit.
• BCM repair/replacement or configuration actions: only if pin-level testing proves the external circuit is normal and the BCM is the source of the circuit-high condition.

Can I Still Drive With B3723?

B3723 is a body system code, so it typically does not prevent the vehicle from moving under its own power. However, it can affect rear visibility if the rear wiper is inoperative, runs unexpectedly, or behaves intermittently. If weather or road spray makes rear visibility unreliable, treat it as a safety concern and avoid driving until the rear wiper system operates correctly.

If the rear wiper runs when it should not, the condition may also increase electrical load and could contribute to battery drain depending on vehicle behavior and how long the wiper remains active.

Repair Costs

Repair cost depends on whether the confirmed root cause is wiring, connector condition, a switch or module issue, or the labor needed to diagnose the fault correctly.