Code
P1660
LINCOLN
P — Powertrain
Output Circuit Check Signal High
Views:
UK: 21
EN: 38
RU: 33
AI status
Completed
Completed
100%
Causes
- Short to battery voltage (B+) on the output circuit
- Corroded, damaged, or loose connector or wiring
- Failed or shorted actuator/sensor connected to the output
- Poor or open ground causing incorrect reference
- Intermittent connection or water intrusion
- PCM/ECM internal driver fault or software anomaly
Symptoms
- MIL (check engine light) illuminated
- Affected component may run continuously, behave erratically, or not function
- Possible drivability issues if the output controls engine-critical devices
- Intermittent faults or inability to clear the code until repair
- Vehicle may fail certain self-tests or limp-in mode depending on circuit
What to check
- Retrieve freeze frame and live data with a scan tool; record related codes and battery voltage
- Visually inspect wiring, connectors, and harness routing for damage, corrosion, or pinched wires
- Check for aftermarket devices or recent repairs in the circuit area
- Back-probe the output circuit and measure voltage with key ON and during commanded activation
- Perform continuity and resistance checks to ground and between the output pin and component
- Unplug the downstream component/actuator and see if the code clears or the circuit voltage returns to expected
Signal parameters
- Expected: output sits near 0 V when inactive for low-side drivers or near battery voltage when commanded on for high-side drivers
- Fault condition: measured voltage higher than the expected idle/reference level (e.g., unexpectedly at or above battery voltage on a circuit that should be low)
- Logic-level outputs: expected 0–5 V; any sustained voltage above the design maximum is a fault
- Battery voltage should be within normal range (typically ~12–14.5 V) when evaluating the circuit
Diagnostic algorithm
- Connect a professional scan tool, read all stored codes and freeze-frame data. Note any related or pending codes and current battery voltage.
- Clear codes, perform a key-on/engine-off self-test, and attempt to re-create the code while monitoring live data to confirm repeatability.
- Identify the specific output circuit from the vehicle wiring diagram and locate the corresponding PCM pin and downstream component(s).
- Visually inspect the connector and wiring for damage, corrosion, water intrusion, or aftermarket taps. Repair any obvious damage.
- With harness connector disconnected from the actuator, back-probe the PCM output and measure voltage with key ON and when the PCM commands the output. Compare to expected values.
- Check for short-to-B+ by measuring continuity between the output conductor and battery positive with the circuit disconnected. Also check for unintended continuity to other circuits.
- Check ground integrity for related grounds with a low-resistance test; repair any poor grounds.
- Reconnect the actuator; unplug the actuator and command the output while observing the voltage/current. If unplugging the actuator causes the voltage to return to normal, suspect the actuator or its wiring.
- If wiring and actuators test good, consider PCM driver failure. Confirm with manufacturer-specific diagnostics before replacing the PCM (possible bench test or swap with known-good unit where appropriate).
- After repairs, clear codes, retest the system under the same conditions, and verify the code does not return.
Likely causes
- Pinched or chafed wire that contacts a constant 12 V source
- Connector terminal corrosion causing resistance changes and abnormal readings
- Failed output device that is presenting a short/high load to the driver
- Blown or improperly installed fuse or relay affecting reference voltages
- PCM power stage (output driver) fault
Fault status
Status
PCM detected an output circuit signal above the allowable threshold during an internal check; code stored to indicate an electrical fault on an output driver or its wiring.
Repair difficulty: Medium
Diagnostic time: 1.0-3.0 hours
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