Code
P1028
RENAULT
P — Powertrain
- Brake pedal position (BPP) switch - circuit malfunction
Views:
UK: 3
EN: 10
RU: 7
AI status
Completed
Completed
100%
Causes
- Open or short in BPP switch wiring (to ground or battery)
- Faulty or mechanically sticking brake pedal position (BPP) switch
- Poor connector contact, corrosion, bent pins or water ingress
- Blown fuse or related power supply fault
- Short to other circuits (lighting, ignition) or aftermarket wiring damage
- Faulty body/engine control module input or internal ECU fault
Symptoms
- Brake lights permanently on or not working
- Cruise control may not engage or may disengage immediately
- Shift interlock may not release (automatic gearbox) or start inhibit active on push-button start vehicles
- Brake-related warning light or ECU fault lamp illuminated
- Stored DTCs and possible limp functions related to braking logic
What to check
- Retrieve freeze frame and live data with a scan tool; confirm BPP status and if the signal is stable during pedal travel
- Visual inspection of BPP switch, connector, and wiring for damage, corrosion or water intrusion
- Check related fuses and power/ground circuits for the switch
- Measure voltage at the BPP connector with ignition ON and while actuating the pedal (expected logic states below)
- Perform continuity/resistance checks between switch pins and ECU; check for short to ground or battery
- Wiggle test wiring while monitoring live data for intermittent changes
Signal parameters
- Type: typically a low-voltage digital switch signal (open/closed) or a simple contact to ground/power
- Typical voltages: logical HIGH ≈ 5V or battery voltage via pull-up; logical LOW ≈ 0–1V when switched to ground (vehicle dependent)
- Current draw: very low (milliamps) — switch is a contact, not a powered sensor
- Normal behavior: stable state at rest and opposite state when pedal fully depressed; no rapid toggling or floating voltages
- If CAN-based: BPP status is transmitted as a message; expected state changes should appear in CAN data
Diagnostic algorithm
- Read and record DTC(s) and live BPP data with scan tool; note conditions when fault set. Clear codes and attempt to reproduce.
- Visually inspect BPP switch and harness at the pedal for damage, chafing, connector corrosion, or loose mounting.
- With ignition ON, backprobe the BPP connector: verify reference voltage/pull-up and switch output while operating pedal. Compare to expected logic above.
- Check for continuity between switch output and ECU input; check for unwanted continuity to ground or battery (shorts).
- Wiggle harness and pedal assembly while monitoring live data to find intermittent faults.
- If open/short confirmed at switch, disconnect connector and measure resistance across switch terminals while actuating pedal; replace switch if out of spec or non-switching.
- Repair any wiring (splice or replace harness section), clean/replace corroded connectors, secure grounds and relays/fuses as required.
- If wiring and switch test good, test ECU input circuit for proper operation; consider ECU bench test or replacement only after wiring and switch ruled out.
- After repair, clear codes and verify proper operation in road test and with repeated pedal cycles.
Likely causes
- Damaged wiring harness at pedal or routing points (chafing, pinched)
- Corroded or loose BPP switch connector
- Defective BPP switch
- Blown fuse or poor ground at switch circuit
- Intermittent contact due to pedal geometry or mounting wear
Fault status
Status
P1028 — Brake pedal position (BPP) switch circuit malfunction. The ECU detected an unexpected/open/short or intermittent signal on the BPP input; inspect switch, wiring, connectors, fuses and ECU input.
Repair difficulty: Medium
Diagnostic time: 0.5-2.0 hours
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