Code
B1437
FIAT
B — Body
High/low wiper speed relay coil short to ground
Views:
UK: 4
EN: 5
RU: 5
AI status
Completed
Completed
100%
Causes
- Damaged wiring insulation causing contact between coil feed and chassis ground
- Failed or internally shorted wiper speed relay
- Corroded or water‑ingressed connector making unintended ground
- Faulty BCM/relay driver transistor pulling the coil circuit to ground
- Incorrect aftermarket accessory wiring or recent repair damage
Symptoms
- Wipers do not operate or intermittent operation
- Only one wiper speed (stuck high or low) or loss of specific speed position
- Blown fuse for wiper circuit (possible)
- DTC B1437 stored; possible warning or malfunction indicator on dash
- Unusual heating or burning smell in relay area (in severe shorts)
What to check
- Retrieve freeze‑frame data and confirm B1437 is current or historic
- Visual inspection of relay, relay socket, wiring harness and nearby ground points for damage or corrosion
- Check related fuses and fuseholder for continuity and signs of overheating
- Unplug the wiper relay and check for continuity between coil terminal and chassis ground
- Measure coil resistance across relay coil terminals (compare to expected range)
- With relay removed, perform wiggle test on harness while monitoring for continuity to ground or intermittent faults
Signal parameters
- Expected coil resistance between relay coil terminals: typically in the range of ~20–300 ohms (varies by relay); consult vehicle wiring data
- Coil continuity to chassis ground: should be OPEN/no direct continuity when relay and circuit are intact
- Supply voltage to coil when commanded: ~11–14 V (battery voltage) on supply side; switched side may be pulled to ground by BCM or relay driver
- Expected coil current when energized: typically tens to a few hundred milliamps (varies by relay design)
- Scan tool: BCM command status should show ON when wipers are commanded and no unexpected ground fault
Diagnostic algorithm
- Read and record codes and freeze frame, then clear codes to see if B1437 returns.
- Visually inspect relay, relay socket, wiring harness, and grounds for damage, corrosion or water ingress. Repair obvious damage.
- With ignition off, unplug the wiper relay. Using a multimeter, check resistance between the two coil terminals and verify it falls within the expected range for that relay (consult parts data).
- Check for continuity between each coil terminal and chassis ground. There should be no direct continuity (open). If continuity exists, trace and repair the short in the harness or connector.
- Inspect and backprobe the relay connector with ignition on while commanding the wipers: verify battery feed and that the control side is switched (to ground or +12V depending on circuit) only when commanded. Look for a permanent ground on the control side.
- If the connector and harness appear good and the control side is permanently grounded, suspect BCM/relay driver fault. Confirm by disconnecting the harness and measuring if the ground remains on the BCM output (follow manufacturer safe test procedures).
- Replace the relay with a known good unit and retest. If replacing the relay cures the code, repair or replace the original relay. If not, continue wiring and BCM diagnostics.
- Repair any damaged wiring, terminals, or connectors. Protect repaired wiring from abrasion and moisture. Clear codes and perform functional test of wipers across all speeds.
- If BCM driver is confirmed faulty, replace or reprogram BCM per manufacturer procedure and retest.
Likely causes
- Shorted conductor in the harness near relay or wiper motor (chafed wire or pinched cable)
- Relay coil internally shorted to its housing/ground
- Corrosion or bent terminal at relay connector providing a ground path
- BCM output stage failed and is permanently shorting coil circuit to ground
- Foreign object or moisture in relay socket causing short to ground
Fault status
Status
High/low wiper speed relay coil short to ground detected (B1437). Inspect relay, wiring and BCM output for short to ground. Repair wiring or replace faulty relay/BCM as required.
Repair difficulty: Medium
Diagnostic time: 0.5-2.0 hours
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