Code
P1667
LINCOLN
P — Powertrain
CI Circuit Malfunction
Views:
UK: 26
EN: 33
RU: 25
AI status
Completed
Completed
100%
Causes
- Open or shorted wiring in the CI circuit (to power, ground, or other circuits)
- Corroded, loose, or damaged connector at the CI component or PCM
- Blown fuse or faulty relay supplying the CI circuit
- Failed sensor, actuator, or component served by the CI circuit
- Faulty PCM or other control module (less common)
- Water intrusion, corrosion, or physical damage to harness
Symptoms
- Malfunction Indicator Lamp (MIL) illuminated or stored DTC
- Related system or feature inoperative or intermittent (depends on what CI controls)
- Possible drivability symptoms if the CI circuit affects engine management
- Fault present immediately after rain/engine bay wash if water intrusion is involved
What to check
- Read and record all DTCs and freeze-frame data with a scan tool
- Check battery voltage and charging system health before testing
- Visual inspection of wiring, connectors, harness routing for damage or corrosion
- Inspect and verify all fuses and relays related to the CI circuit
- Check for technical service bulletins (TSBs) or wiring diagrams for CI circuit specifics
- Perform wiggle test of harness while monitoring live data or scanning for pending codes
Signal parameters
- Reference supply: typically 5 V (sensor reference) or 12 V (power feed) — verify against vehicle wiring diagram
- Signal voltage: expected ~0–5 V for low-voltage sensors; ~0 V when off and ~12 V when switched on for power feeds
- Continuity: low resistance between component pin and PCM pin (typically < 5 ohms for short runs)
- Resistance to ground: near infinite for signal lines (no short), low for dedicated ground circuits
- Current draw: compare actuator current to factory spec when energized (use clamp meter if needed)
Diagnostic algorithm
- Connect a scan tool, record P1667 plus any other DTCs and freeze-frame data; note whether code is current or history.
- Identify all components, fuses, relays, and connectors on the CI circuit using the vehicle wiring diagram/service manual.
- Perform a visual inspection of the CI harness, connectors, and related components for corrosion, damage, or loose pins.
- Verify supply and ground: with ignition on, check for proper battery voltage at the CI circuit power feed and a good ground reference at the component connector.
- Check related fuses and relays; replace if blown or suspect and re-test.
- Measure continuity/resistance between the component connector pin and the PCM pin with battery disconnected to confirm no open circuit.
- Test for shorts: with battery disconnected, check for continuity from the CI signal to ground and to battery positive to identify short conditions.
- If the circuit and connectors test good, monitor the signal with a scan tool or oscilloscope while operating the vehicle or commanding the component to reproduce the fault.
- If the component is out of spec, disconnect it and test or replace the component (sensor/actuator). Retest for code clearance.
- If wiring and component are good and the fault returns, consider PCM or module fault — confirm with module bench test or dealer-level diagnostics before replacement.
- After any repair, clear codes and perform a test drive or readiness cycle to verify the fault does not return.
Likely causes
- Damaged connector or corroded pin at the CI component or PCM
- Short to ground or to battery voltage on the circuit
- Blown fuse or failed relay feeding the CI circuit
- Defective CI-related sensor/actuator
- Wiring chafed where it passes through body or engine harness
Fault status
Status
PCM detected a malfunction in the CI circuit (electrical fault). The condition may be current (active) or stored; further testing is required to identify the cause.
Repair difficulty: Medium
Diagnostic time: 0.5-2.0 hours
Similar codes
Your experience will help others
+100 karma for a short comment :)
Was this AI description helpful?
Your feedback helps improve AI descriptions.
👍 Like
0
👎 Dislike
0
Send to email