Code
P0376
Generic
P — Powertrain
Timing Reference High Resolution Signal B Too Many Pulses
AI status
Completed
Completed
100%
Causes
- Faulty high-resolution timing sensor (cam/crank/secondary sensor B)
- Damaged or shorted wiring or connector (signal shorted to voltage or noisy ground)
- Incorrect or damaged timing reluctor/tone wheel (extra teeth or debris)
- Aftermarket or incompatible timing component installed
- PCM/ECM software or internal fault
- Electrical interference from adjacent circuits or ignition components
Symptoms
- Malfunction Indicator Lamp (MIL) illuminated
- Hard starting or no-start
- Rough idle, stalling, or misfires
- Poor throttle response or reduced power
- Irregular or incorrect cam/crank correlation on scope
- Possible limp-home mode or reduced functionality
What to check
- Read freeze frame data and note engine speed and operating conditions when code set
- Scan for related codes (cam/crank sensor, range/performance, circuit faults)
- Visually inspect sensor B connector and wiring for damage, corrosion, or pin push-out
- Check for loose or missing reluctor teeth, damaged tone wheel, or metal debris near sensor
- Backprobe sensor connector and observe signal with a good oscilloscope (compare to reference channel)
- Perform a wiggle test on harness with engine running (if safe) to reproduce code
Signal parameters
- Signal type: Hall-effect, Variable Reluctance (VR), or magnetic pickup depending on vehicle
- Amplitude: Hall sensors ~0–5V digital square wave; VR sensors produce AC voltage that rises with rpm (typical RMS varies by design)
- Duty cycle: Hall sensors usually near 50% at steady RPM; VR output is sinusoidal/AC
- Frequency: proportional to engine speed; pulses per cam/crank revolution determined by tone wheel design
- Expected pulse count: fixed pattern defined by manufacturer (extra pulses detected = fault)
- Noise tolerance: small jitter OK, but extra discrete edges/pulses beyond expected pattern indicate problem
Diagnostic algorithm
- Record freeze frame and all stored codes. Note engine speed and conditions.
- Inspect sensor B connector and wiring for corrosion, pin damage, exposed conductors, or repair splice issues.
- With a lab-quality oscilloscope, capture the high-resolution signal B waveform while cranking and at idle. Compare pattern, pulse count, and timing relationship to a known-good reference (or the other timing sensor channel).
- If extra pulses or noise are present on the waveform, inspect the reluctor/tone wheel for damage, foreign material, or incorrect installation. Repair or replace as needed.
- Check sensor mounting and air gap; adjust to spec. Replace sensor if waveform shows weak/noisy signal or internal chatter.
- Repair any damaged wiring (shorts to 12V or low resistance to ground) and secure connectors. Re-test waveform after repair.
- Clear codes and perform road test under similar conditions that set the fault. Re-scan for recurrence.
- If wiring and sensor are verified good but extra pulses persist, verify PCM software/calibration and consider PCM evaluation or reflash per manufacturer guidance.
- If code returns after replacement/repairs, document waveforms and consider professional assistance for advanced diagnosis.
Likely causes
- Broken or frayed signal wire causing intermittent shorts to battery or noise
- Contaminated or damaged sensor face (metal shavings, pitting) producing extra pulses
- Magnetic reluctor wheel with bent/extra material or foreign object producing spurious edges
- Loose connector or poor ground at sensor
- Failed Hall-effect or magnetic pickup sensor internal electronics
Fault status
Status
ECM detected more pulses than expected on Timing Reference High Resolution Signal B. The condition exceeded the allowed pattern tolerance and set DTC P0376; MIL may be illuminated and engine timing functions could be affected.
Repair difficulty: Medium
Diagnostic time: 0.5-3.0 hours
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Code
P0376
GWM
P — Powertrain
- The number of pulses of the timer B signal is higher than the norm
AI status
Completed
Completed
100%
Causes
- Faulty high-resolution timing sensor (cam/crank/secondary sensor B)
- Damaged or shorted wiring or connector (signal shorted to voltage or noisy ground)
- Incorrect or damaged timing reluctor/tone wheel (extra teeth or debris)
- Aftermarket or incompatible timing component installed
- PCM/ECM software or internal fault
- Electrical interference from adjacent circuits or ignition components
Symptoms
- Malfunction Indicator Lamp (MIL) illuminated
- Hard starting or no-start
- Rough idle, stalling, or misfires
- Poor throttle response or reduced power
- Irregular or incorrect cam/crank correlation on scope
- Possible limp-home mode or reduced functionality
What to check
- Read freeze frame data and note engine speed and operating conditions when code set
- Scan for related codes (cam/crank sensor, range/performance, circuit faults)
- Visually inspect sensor B connector and wiring for damage, corrosion, or pin push-out
- Check for loose or missing reluctor teeth, damaged tone wheel, or metal debris near sensor
- Backprobe sensor connector and observe signal with a good oscilloscope (compare to reference channel)
- Perform a wiggle test on harness with engine running (if safe) to reproduce code
Signal parameters
- Signal type: Hall-effect, Variable Reluctance (VR), or magnetic pickup depending on vehicle
- Amplitude: Hall sensors ~0–5V digital square wave; VR sensors produce AC voltage that rises with rpm (typical RMS varies by design)
- Duty cycle: Hall sensors usually near 50% at steady RPM; VR output is sinusoidal/AC
- Frequency: proportional to engine speed; pulses per cam/crank revolution determined by tone wheel design
- Expected pulse count: fixed pattern defined by manufacturer (extra pulses detected = fault)
- Noise tolerance: small jitter OK, but extra discrete edges/pulses beyond expected pattern indicate problem
Diagnostic algorithm
- Record freeze frame and all stored codes. Note engine speed and conditions.
- Inspect sensor B connector and wiring for corrosion, pin damage, exposed conductors, or repair splice issues.
- With a lab-quality oscilloscope, capture the high-resolution signal B waveform while cranking and at idle. Compare pattern, pulse count, and timing relationship to a known-good reference (or the other timing sensor channel).
- If extra pulses or noise are present on the waveform, inspect the reluctor/tone wheel for damage, foreign material, or incorrect installation. Repair or replace as needed.
- Check sensor mounting and air gap; adjust to spec. Replace sensor if waveform shows weak/noisy signal or internal chatter.
- Repair any damaged wiring (shorts to 12V or low resistance to ground) and secure connectors. Re-test waveform after repair.
- Clear codes and perform road test under similar conditions that set the fault. Re-scan for recurrence.
- If wiring and sensor are verified good but extra pulses persist, verify PCM software/calibration and consider PCM evaluation or reflash per manufacturer guidance.
- If code returns after replacement/repairs, document waveforms and consider professional assistance for advanced diagnosis.
Likely causes
- Broken or frayed signal wire causing intermittent shorts to battery or noise
- Contaminated or damaged sensor face (metal shavings, pitting) producing extra pulses
- Magnetic reluctor wheel with bent/extra material or foreign object producing spurious edges
- Loose connector or poor ground at sensor
- Failed Hall-effect or magnetic pickup sensor internal electronics
Fault status
Status
ECM detected more pulses than expected on Timing Reference High Resolution Signal B. The condition exceeded the allowed pattern tolerance and set DTC P0376; MIL may be illuminated and engine timing functions could be affected.
Repair difficulty: Medium
Diagnostic time: 0.5-3.0 hours
Similar codes
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Code
P0376
HUMMER
P — Powertrain
Timing Reference High Resolution Signal B Too Many Pulses
AI status
Completed
Completed
100%
Causes
- Faulty high-resolution timing sensor (cam/crank/secondary sensor B)
- Damaged or shorted wiring or connector (signal shorted to voltage or noisy ground)
- Incorrect or damaged timing reluctor/tone wheel (extra teeth or debris)
- Aftermarket or incompatible timing component installed
- PCM/ECM software or internal fault
- Electrical interference from adjacent circuits or ignition components
Symptoms
- Malfunction Indicator Lamp (MIL) illuminated
- Hard starting or no-start
- Rough idle, stalling, or misfires
- Poor throttle response or reduced power
- Irregular or incorrect cam/crank correlation on scope
- Possible limp-home mode or reduced functionality
What to check
- Read freeze frame data and note engine speed and operating conditions when code set
- Scan for related codes (cam/crank sensor, range/performance, circuit faults)
- Visually inspect sensor B connector and wiring for damage, corrosion, or pin push-out
- Check for loose or missing reluctor teeth, damaged tone wheel, or metal debris near sensor
- Backprobe sensor connector and observe signal with a good oscilloscope (compare to reference channel)
- Perform a wiggle test on harness with engine running (if safe) to reproduce code
Signal parameters
- Signal type: Hall-effect, Variable Reluctance (VR), or magnetic pickup depending on vehicle
- Amplitude: Hall sensors ~0–5V digital square wave; VR sensors produce AC voltage that rises with rpm (typical RMS varies by design)
- Duty cycle: Hall sensors usually near 50% at steady RPM; VR output is sinusoidal/AC
- Frequency: proportional to engine speed; pulses per cam/crank revolution determined by tone wheel design
- Expected pulse count: fixed pattern defined by manufacturer (extra pulses detected = fault)
- Noise tolerance: small jitter OK, but extra discrete edges/pulses beyond expected pattern indicate problem
Diagnostic algorithm
- Record freeze frame and all stored codes. Note engine speed and conditions.
- Inspect sensor B connector and wiring for corrosion, pin damage, exposed conductors, or repair splice issues.
- With a lab-quality oscilloscope, capture the high-resolution signal B waveform while cranking and at idle. Compare pattern, pulse count, and timing relationship to a known-good reference (or the other timing sensor channel).
- If extra pulses or noise are present on the waveform, inspect the reluctor/tone wheel for damage, foreign material, or incorrect installation. Repair or replace as needed.
- Check sensor mounting and air gap; adjust to spec. Replace sensor if waveform shows weak/noisy signal or internal chatter.
- Repair any damaged wiring (shorts to 12V or low resistance to ground) and secure connectors. Re-test waveform after repair.
- Clear codes and perform road test under similar conditions that set the fault. Re-scan for recurrence.
- If wiring and sensor are verified good but extra pulses persist, verify PCM software/calibration and consider PCM evaluation or reflash per manufacturer guidance.
- If code returns after replacement/repairs, document waveforms and consider professional assistance for advanced diagnosis.
Likely causes
- Broken or frayed signal wire causing intermittent shorts to battery or noise
- Contaminated or damaged sensor face (metal shavings, pitting) producing extra pulses
- Magnetic reluctor wheel with bent/extra material or foreign object producing spurious edges
- Loose connector or poor ground at sensor
- Failed Hall-effect or magnetic pickup sensor internal electronics
Fault status
Status
ECM detected more pulses than expected on Timing Reference High Resolution Signal B. The condition exceeded the allowed pattern tolerance and set DTC P0376; MIL may be illuminated and engine timing functions could be affected.
Repair difficulty: Medium
Diagnostic time: 0.5-3.0 hours
Similar codes
Repair manuals
Manual library for HUMMER
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