B1C28 — Footswitch out

Causes

• Open or short circuit in footswitch wiring or connector
• Corroded, bent or loose connector pins at the footswitch or control module
• Failed footswitch (mechanical or electrical failure)
• Poor ground or supply voltage to the switch
• Water ingress or contamination at the switch or connector
• Body control module (BCM) or related module fault or software issue

Symptoms

• Associated footswitch-controlled features inoperative (e.g., footwell lighting, hands-free features, or the specific function the switch controls)
• Stored B1C28 fault and MIL or message on instrument cluster (depending on vehicle)
• Intermittent operation of the related function (works sometimes)
• No obvious mechanical problem with pedal or switch actuation

What to check

• Read and record DTC(s) and freeze frame with a capable diagnostic scanner; note module reporting the code
• Check for related or historical codes in BCM or other modules
• Visually inspect footswitch, connector and wiring for damage, corrosion, water, or pin deformation
• Check connector is fully seated and locking clip engaged
• Perform wiggle test on harness while monitoring live data or continuity
• Check vehicle service information for specific pinouts, wiring diagrams and reference values

Signal parameters

• Supply/reference voltages vary by model — typical reference can be ~5 V or switched 12 V; consult service data before measuring
• Switch closed: continuity expected (low resistance, near 0 Ω) between switch terminals or signal pulled to ground depending on circuit design
• Switch open: high resistance (open circuit) or signal at supply/reference voltage
• Signal should toggle cleanly between the two states when actuated (no noisy or floating voltage)
• If equipped, check module live data for a digital state (0/1) or measured voltage change when actuated

Similar codes

Causes

• Open or short circuit in footswitch wiring or connector
• Corroded, bent or loose connector pins at the footswitch or control module
• Failed footswitch (mechanical or electrical failure)
• Poor ground or supply voltage to the switch
• Water ingress or contamination at the switch or connector
• Body control module (BCM) or related module fault or software issue

Symptoms

• Associated footswitch-controlled features inoperative (e.g., footwell lighting, hands-free features, or the specific function the switch controls)
• Stored B1C28 fault and MIL or message on instrument cluster (depending on vehicle)
• Intermittent operation of the related function (works sometimes)
• No obvious mechanical problem with pedal or switch actuation

What to check

• Read and record DTC(s) and freeze frame with a capable diagnostic scanner; note module reporting the code
• Check for related or historical codes in BCM or other modules
• Visually inspect footswitch, connector and wiring for damage, corrosion, water, or pin deformation
• Check connector is fully seated and locking clip engaged
• Perform wiggle test on harness while monitoring live data or continuity
• Check vehicle service information for specific pinouts, wiring diagrams and reference values

Signal parameters

• Supply/reference voltages vary by model — typical reference can be ~5 V or switched 12 V; consult service data before measuring
• Switch closed: continuity expected (low resistance, near 0 Ω) between switch terminals or signal pulled to ground depending on circuit design
• Switch open: high resistance (open circuit) or signal at supply/reference voltage
• Signal should toggle cleanly between the two states when actuated (no noisy or floating voltage)
• If equipped, check module live data for a digital state (0/1) or measured voltage change when actuated

Similar codes