P1565

Code

GMC P — Powertrain

Cruise Servo Position Sensor

Brand: GMC

Type: P — Powertrain

Views: UK: 35 EN: 43 RU: 36

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Page language: EN

Causes

Damaged, corroded, or disconnected sensor connector or wiring harness (open, short to ground, short to power).
Failed cruise servo position sensor (internal fault or wear).
Faulty cruise servo/actuator assembly (mechanical binding or internal electronics failure).
Poor power or ground to the sensor/servo (blown fuse, bad junction, poor chassis ground).
Intermittent connector contact (water intrusion, corrosion).
PCM/BCM internal fault or software anomaly (less common).

Symptoms

Cruise control will not engage or is intermittent.
Cruise disengages immediately after trying to set speed.
Check Engine Light (MIL) may be illuminated.
Diagnostic trouble code P1565 stored in PCM.
Possible limp/limited functionality of speed control or related throttle control symptoms if integrated with throttle actuator systems.

What to check

Read and record all stored codes and freeze frame/live data with a scan tool; note any related codes (throttle, actuator, brake switch).
Visual inspection of cruise servo/actuator, sensor connector, and wiring for damage, corrosion, or water intrusion.
Check fuses and power/ground circuits feeding the cruise servo and sensor.
Backprobe sensor connector with key ON and measure reference voltage, ground continuity, and signal voltage while commanding servo or moving throttle linkage (if serviceable).
Wiggle test harness while monitoring live data for intermittent changes.
If available, command the cruise servo/actuator with a bidirectional scan tool to observe movement and sensor feedback.

Signal parameters

Reference voltage: typically 5 V (may vary by model); verify exact spec from service manual.
Sensor signal: typically a variable analog voltage proportional to position (commonly ~0.5–4.5 V across travel).
At rest/parked position the sensor voltage often sits near one end of the range (vehicle-specific).
Signal should change smoothly and proportionally as the servo/actuator moves; erratic jumps, stuck values, or open/short indications are faults.
Expected resistance values (if applicable) depend on sensor design—consult vehicle service data before comparing ohms.

Diagnostic algorithm

Connect a professional scan tool. Read and record P1565 and any related codes; capture freeze frame and live data for cruise servo position and related sensors.
Verify vehicle inhibiting inputs (brake switch, clutch switch, park/neutral, cruise master switch) are correct and not preventing cruise operation.
Perform a visual inspection of the cruise servo/position sensor connector and wiring harness; repair obvious damage, corrosion, or loose pins.
With key ON (engine off unless specified), backprobe the sensor connector: confirm reference voltage present, good ground continuity, and measure signal voltage. Compare to service specifications.
Command the cruise servo (if supported) while watching live data: confirm the actuator moves and the position sensor output changes smoothly across its range. Note any dead spots or non-linear behavior.
Perform continuity/resistance checks on the harness between the sensor connector and the PCM to locate opens/shorts. Repair any wiring faults found.
If wiring and power/grounds are good but sensor output is incorrect or non-responsive, replace the cruise servo position sensor or the entire actuator assembly as required by design.
After repair or replacement, clear codes and road test. Re-scan to ensure P1565 does not return and that cruise operates normally.
If problem persists after component replacement and wiring verified, consider PCM/BCM fault and consult manufacturer technical service information for advanced diagnostics or software updates.

Likely causes

Wiring or connector fault between PCM and cruise servo position sensor (most common).
Failed position sensor within the cruise servo/actuator assembly.
Loss of sensor power or ground.
Mechanical binding preventing servo movement or giving implausible sensor readings.
PCM hardware/software fault (least common).

Fault status

⚠️ Status

P1565 — Cruise Servo Position Sensor: PCM has detected invalid or missing position sensor signal from the cruise servo/actuator circuit. Cruise control may be disabled until fault is corrected.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0-3.0 hours

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