Code
P102C
DACIA
P — Powertrain
Cruise control system - circuit malfunction
AI status
Completed
Completed
100%
Causes
- Blown fuse or faulty relay supplying cruise control/BCM
- Damaged wiring harness or pinched/shorted wires to cruise control switch/module
- Corroded or loose connector at cruise control switch, BCM or cruise actuator
- Faulty cruise control switch or stalk assembly
- Faulty BCM / cruise control module or internal electronic failure
- Loss of CAN/bus communication between control modules
Symptoms
- Cruise control unavailable or cannot be engaged
- Cruise control indicator lamp off or flashing
- Cruise disengages unexpectedly
- Stored DTC P102C (may be only symptom)
- In some cases related warning lights or loss of other convenience functions
What to check
- Read DTCs and freeze frame data with a capable scan tool; note related U-codes
- Check battery voltage (engine off and cranking) and main grounds
- Inspect/verify fuse and relay for cruise/BCM power
- Visual inspection of wiring and connectors for damage, corrosion or loose pins at cruise switch, BCM and actuator
- Verify brake and clutch switch operation and continuity
- Check CAN bus presence and voltages on CAN H/L at relevant modules
Signal parameters
- Battery supply to cruise circuit: ~12 V (key on)
- Ground continuity: low resistance (
- CAN bus idle voltage: ~2.5 V on CAN_H and CAN_L midpoint (verify differential ~0 V idle and ~2.5 V common mode)
- Cruise switch voltage/resistance: varies by model (switch-to-BCM voltages or resistor ladder values change when buttons pressed) — consult wiring diagram for expected values
- Brake/clutch switch: open/closed logic — typically close = battery voltage to BCM or ground (verify against wiring diagram)
- Module supply fuse feed present with ignition on
Diagnostic algorithm
- Connect a full-function scan tool. Read and record all stored and pending DTCs and live data. Note any related U-codes (CAN/comm errors) or P-codes.
- Confirm P102C is current. Clear codes and attempt to reproduce. If intermittent, monitor while operating cruise controls.
- Check battery voltage and main chassis/engine grounds. Repair any low voltage or poor ground before further diagnosis.
- Inspect and verify fuses/relays for cruise control/BCM. Replace if faulty and retest.
- Visually inspect connectors and wiring to the cruise switch, BCM/cruise module and actuator. Repair any damaged wiring, pins or corrosion.
- Verify brake and clutch switch function and continuity (they inhibit cruise). Replace or adjust if out of tolerance.
- With ignition on, measure supply voltage and ground at the cruise switch/module connectors. Compare to expected values from wiring diagram.
- Check CAN bus communication at BCM and cruise module — verify presence and no bus errors. If lost communication, trace to faulty module, wiring or terminations.
- Test cruise control switch/stalk: measure outputs while pressing buttons or use substitute known-good switch if available.
- If wiring and inputs are good but fault persists, test/replace the cruise control module or BCM per manufacturer's procedures.
- After repairs, clear codes and perform road test to confirm cruise function and absence of P102C.
Likely causes
- Open or short in the cruise control switch wiring
- Connector corrosion/poor contact at BCM or cruise module
- Faulty cruise switch or module
- Intermittent loss of CAN communication to instrument/BCM
- Blown fuse for cruise control supply
Fault status
Status
Cruise control circuit malfunction detected — cruise may be disabled. Diagnostic trouble code P102C stored in module memory.
Repair difficulty: Medium
Diagnostic time: 1.0-2.5 hours
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