Code
P1565
OLDSMOBILE
P — Powertrain
Cruise Servo Position Sensor
AI status
Completed
Completed
100%
Causes
- Open or shorted wiring between cruise servo position sensor and PCM
- Poor or corroded connector pins at sensor or PCM
- Faulty cruise servo position sensor (potentiometer or hall element)
- Faulty cruise servo/actuator (mechanical binding or internal damage)
- Intermittent ground or reference voltage loss
- PCM software or internal fault (less common)
Symptoms
- Cruise control inoperative or disabled
- Cruise may disengage unexpectedly
- Stored P1565 trouble code and possibly related throttle/cruise codes
- No change or erratic position reading when monitoring servo position PID
- Possible check engine light (MIL) illuminated
What to check
- Retrieve freeze frame and stored codes with a scan tool; record live data for cruise servo position PID
- Visually inspect connector and wiring at the cruise servo for damage, corrosion, or looseness
- Back-probe sensor connector and verify reference voltage (typically 5 V) and good ground
- Verify sensor output voltage changes smoothly as the servo/actuator is moved through its travel
- Wiggle harness while monitoring signal to check for intermittent faults
- Measure continuity and resistance to PCM where applicable; check for shorts to battery or ground
Signal parameters
- Reference voltage to sensor: approximately 5 V (check vehicle-specific value)
- Signal output: variable analog voltage (commonly ~0.5–4.5 V) proportional to servo position
- Signal should change smoothly with actuator travel, no sudden jumps or dropouts
- Circuit resistance (sensor potentiometer type): manufacturer-specific — expect smooth variable resistance across travel
- No short to battery (would read ~12 V) and no short to ground (would read ~0 V) on the signal line
Diagnostic algorithm
- Connect a quality scan tool. Read and record PIDs related to cruise servo position and any related codes. Note freeze frame data.
- Perform a visual inspection of the servo, connectors, and harness. Repair any obvious damage or corrosion and clear codes to retest.
- With ignition ON (engine off) back-probe the sensor connector. Confirm reference voltage (≈5 V) and a good ground. If reference or ground missing, trace wiring to power/ground source and repair.
- Monitor signal voltage while an assistant moves the cruise actuator through its full travel (or use actuator command if available). Signal should vary smoothly across range. If signal stuck or erratic, suspect sensor or wiring.
- If signal is out of range or intermittent, check continuity between sensor signal pin and PCM pin with harness unplugged. Repair any opens/shorts.
- If wiring and connectors are good but signal faulty, remove and bench-test or replace the cruise servo/position sensor assembly. Re-test function and codes.
- After repairs, clear codes and perform road test/repeat activation to confirm the sensor reports correctly and P1565 does not return.
- If problem persists after replacement and wiring verified, consider PCM input circuit fault and consult manufacturer service information before replacing PCM.
Likely causes
- Damaged or chafed wiring harness to the cruise servo
- Water intrusion or corrosion at the sensor connector
- Worn sensor inside the cruise servo (age-related)
- Servo mechanism binding so sensor cannot move smoothly
- Loose or poor ground at engine/chassis ground near servo
Fault status
Status
Cruise servo position sensor circuit malfunction — PCM detects invalid, out-of-range, or missing position signal from the cruise control servo/actuator.
Repair difficulty: Medium
Diagnostic time: 1.0-2.0 hours
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