Code
P1282
BUICK
P — Powertrain
Accelerator Pedal Position Sensor 2 Circuit Low Voltage
AI status
Completed
Completed
100%
Causes
- Damaged or disconnected accelerator pedal sensor connector
- Open or shorted APS2 wiring (short to ground)
- Corroded or bent pins in harness/connector
- Failed accelerator pedal position sensor (APS2)
- Low or absent reference voltage (VREF) from PCM (~5 V)
- Poor PCM ground or damaged PCM (rare)
Symptoms
- Check Engine MIL illuminated
- Reduced engine power / limp mode possible
- Poor or no throttle response from pedal
- Inconsistent or stuck idle or hesitation on acceleration
- Stored related freeze frame data showing low APS2 voltage
What to check
- Read freeze frame and current live data with a scan tool; note APS1 and APS2 voltages and correlation
- Visually inspect accelerator pedal assembly, connector, and wiring for damage, corrosion, or water intrusion
- Backprobe pedal connector and measure VREF (should be ~5.0 V) with key ON (engine off)
- Measure APS2 signal voltage at rest and with pedal movement using a DVOM or oscilloscope
- Check for continuity and shorts: APS2 signal to PCM, signal to ground, and to VREF
- Wiggle test pedal harness while monitoring live data for intermittent changes
Signal parameters
- VREF (reference) from PCM: approximately 5.0 V (key ON) — verify exact spec in service manual
- Sensor ground: ~0 V (good continuity to chassis/PCM ground)
- APS signal voltages typically range ~0.2–4.8 V depending on pedal position; at rest often ~0.5–1.0 V and at wide-open ~4.0–4.5 V (model-dependent)
- Low-voltage fault threshold: APS2 signal below ~0.2–0.4 V (manufacturer set) or signal not correlating with APS1 — check factory data for exact thresholds
Diagnostic algorithm
- Connect a scan tool and record freeze frame/live data: note APS1 and APS2 voltages and any related codes (e.g., P1281, P2138).
- Visually inspect pedal assembly, connector, and harness for damage, pins pushed out, corrosion, or water intrusion. Repair any physical damage.
- With key ON (engine off), backprobe the pedal connector: verify VREF ~5.0 V, sensor ground continuity to chassis/PCM ground, and measure APS2 signal voltage at rest. If VREF or ground missing, trace to PCM/power distribution and repair.
- Operate pedal while monitoring APS2 voltage. If voltage remains low or does not change, suspect wiring or sensor. Perform wiggle test on harness while observing live data to isolate intermittent faults.
- Check wiring for short to ground: disconnect pedal connector and measure resistance from APS2 signal pin to chassis ground — low resistance indicates short. Repair wiring as needed.
- If wiring and connectors test good, replace the accelerator pedal position sensor assembly (common service item). Use OEM or correct replacement part.
- After repair, clear codes and retest: verify APS voltages and proper correlation between APS1 and APS2 during full pedal travel and complete a road test to confirm no return of the code.
- If fault persists after sensor and wiring checks, evaluate PCM inputs and grounds; consult manufacturer service information for PCM bench testing or reprogramming procedures.
Likely causes
- Connector contamination/corrosion at pedal or harness
- Broken/shorted wire in harness near pedal or footwell (flex point)
- Failed APS2 internal electronics
- Lost 5V reference or ground at pedal assembly
Fault status
Status
P1282 — Accelerator Pedal Position Sensor 2 Circuit Low Voltage: PCM detected APS2 signal below expected threshold. Possible causes: bad sensor, open/shorted wiring, loss of VREF or ground, or connector corrosion. May result in reduced throttle response or limp mode.
Repair difficulty: Medium
Diagnostic time: 0.5-2.0 hours
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