Code
CF26
CITROEN
C — Chassis
Rear right indicator lighting fault: Open circuit
AI status
Completed
Completed
100%
Causes
- Burned-out or disconnected bulb (incandescent or LED failure)
- Broken or corroded connector at the lamp or harness
- Damaged wiring (open circuit) between BCM and rear right lamp
- Faulty ground connection at the lamp
- Faulty lamp socket or connector pins
- Body control module / lighting module internal fault or poor connector contact
Symptoms
- Rear right indicator does not light when turn signal is activated
- Turn signal warning on instrument cluster (bulb-out or lamp-fault message)
- Turn signal may blink faster or erratically if the system detects a fault elsewhere
- No voltage present at rear right lamp connector with signal active
What to check
- Scan BCM/lighting module for stored faults and freeze-frame data
- Visually inspect the rear right lamp bulb and socket for damage or corrosion
- Check fuses related to exterior lighting (consult vehicle fuse chart)
- Inspect connector and wiring at lamp for corrosion, pin damage, or disconnection
- Verify continuity between lamp connector and BCM using a multimeter
- Measure voltage at lamp connector with turn signal ON and engine on/off as appropriate
Signal parameters
- Expected supply voltage at lamp connector when activated: approx. battery voltage (11–14.5 V)
- Expected open-circuit reading: no voltage or infinite resistance at lamp connector with circuit active
- Typical turn signal flash frequency: about 60–120 flashes per minute (≈1–2 Hz)
- Incandescent lamp current draw: typically hundreds of mA to ~1–2 A (LEDs draw much less, typically tens to a few hundred mA)
- Continuity check: low resistance from lamp + terminal to BCM output when wiring intact; low resistance from lamp ground to chassis ground
Diagnostic algorithm
- Read and record fault code(s) with a diagnostic scanner; note related network/BCM faults.
- Visually inspect the rear right lamp, housing, bulb type (incandescent vs LED) and socket for obvious issues; replace bulb with known-good one to confirm.
- Operate turn signal while measuring voltage at the lamp connector (positive and ground) with a multimeter. If no voltage, proceed to wiring checks.
- Check for continuity between the lamp + terminal and the BCM output pin; if open, isolate the wire and inspect for damage, chafing, or connector corrosion.
- Verify good ground at lamp: measure resistance between lamp ground and vehicle chassis (should be low). Repair ground if high resistance.
- Inspect and test connectors at the lamp and at wiring junctions (inside trunk/boot, tailgate, or harness grommets). Repair or replace corroded connectors.
- If wiring and lamp are good but fault persists, inspect BCM connectors and wiring to BCM for continuity and pin integrity; check for water ingress or corrosion.
- If BCM or lighting module communication errors are present, confirm CAN/BUS health and address any module faults before replacing lamps or wiring.
- After repairs, clear DTCs and test the turn signal function several times and inspect for recurrence of CF26.
- If intermittent or no visible wiring damage and diagnostics point to module fault, consult manufacturer guidance before replacing BCM/lighting module.
Likely causes
- Bulb filament open (most common)
- Plug/connector pushed out, corroded or water-damaged at rear lamp
- Damaged wiring from trunk hinge/chassis flex point
- Broken ground strap or poor chassis ground at lamp location
- BCM pin contact corroded or broken at the module connector
Fault status
Status
Rear right indicator: open circuit detected
Repair difficulty: Medium
Diagnostic time: 0.5-1.5 hours
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