Explanation of Code P068A: “PCM Power Relay De-Energization Performance”
Severity
- Level : 🔴 High (risk of complete engine failure or no-start).
- Urgency :
- Vehicle may stall or not start.
- Possible PCM damage (high replacement cost).
Symptoms
- 🚗 Engine does not start or intermittent starting.
- ⚠️ Check engine light on (MIL) and related codes (e.g., P068B).
- 🔌 Random electrical issues (erratic accessory behavior).
- 📉 Loss of power or unstable idle.
Main Causes
- Faulty PCM power relay: Oxidized contacts or faulty coil.
- Electrical circuit problem:
- Blown fuse (e.g., 30A fuse in under-hood box).
- Damaged wiring (cut wires, short circuits, corrosion).
- PCM failure: Rare but possible (software error or internal component failure).
Diagnostic Procedure
Step 1: Visual Inspection
- Check the PCM relay: Locate it in the fuse box (refer to vehicle manual).
- Inspect fuses: Use a multimeter in continuity mode.
- Inspect connectors: Corrosion, loose or burnt wires.
Step 2: PCM Relay Test
- Resistance test: Measure coil resistance (typically 50-120 Ω).
- Operation test: Apply 12V to the coil and check for relay “click”.
Step 3: Electrical Measurements
- Power supply voltage: Check for 12V at terminal 30 (constant power).
- Ignition signal: 12V at terminal 86 when key is in ON position.
- Output to PCM: Check voltage at terminal 87 after relay activation.
Step 4: PCM Analysis
- Use an advanced OBD2 scanner (e.g., Autel MaxiCOM) to:
- Read live data (PCM supply voltage).
- Check related codes (e.g., P0562 for low system voltage).
Solutions & Costs
| Problem | Solution | Average Cost |
|---|---|---|
| Faulty PCM relay | Relay replacement | €20 – €80 |
| Blown fuse | Fuse replacement | €5 – €20 |
| Damaged wiring | Harness repair or replacement | €50 – €300 |
| Faulty PCM | Reprogramming or replacement | €500 – €1500 |
Mistakes to Avoid
- ❌ Ignoring fuses: A blown fuse may hide a more serious issue.
- ❌ Testing relay without disconnecting battery: Risk of short circuit.
- ❌ Neglecting connectors: Clean them with contact spray (e.g., Kontakt 60).
Practical Case
- Problem: Code P068A on a 2015 Jeep Grand Cherokee with intermittent starting.
- Diagnosis: Oxidized PCM relay (coil resistance at 200 Ω, out of specification).
- Solution: Relay replacement (€40) + connector cleaning.
Frequently Affected Vehicles
- Audi: A4, Q5.
- Dodge/Jeep/Ram: Grand Caravan, Wrangler, 1500.
- Volkswagen: Passat, Tiguan.
Pro Tips
- Use an OEM relay: Aftermarket relays may not meet controlled de-energization timing.
- Check TSBs: Some models have software updates to fix this code (e.g., TSB 18-092-16 for Dodge).
- Test under load: Measure voltage with relay activated to detect abnormal voltage drops.
If the problem persists after relay replacement, consult an automotive electrician to avoid damaging the PCM! 🔧🔋