NO-START / SYNC

CKP/CMP CORRELATION

Capture crankshaft and camshaft signals together to evaluate signal integrity and mechanical synchronization.

ESTIMATED SETUP5–10 min2 channels

WHY BEFORE DISASSEMBLY

CAPTURE THE SYSTEM
AS IT FAILED.

Timing-cover or engine disassembly is expensive and can destroy the evidence. A correlation capture can show whether both sensors are active, whether dropouts exist and whether the relationship has shifted before mechanical access begins.

Reading the signal

Good waveform

Crank and cam edges maintain the specified relationship over repeated engine cycles. Missing-tooth or index features repeat at their intended locations. Compare at the same VVT command and operating state as a verified reference.

Faulty waveform

A repeatable phase displacement may indicate mechanical timing, phaser position or target movement. Random missing edges or noise point toward a signal or circuit issue. A visually tidy pattern can still be out of time; the reference must match the engine and test conditions.

Common mistakes

AVOID THE
FALSE CLUE.

Testing with the connector unplugged when the fault only appears under load.
Using a generic voltage value instead of the vehicle-specific specification.
Skipping power, ground and reference checks before condemning the component.
Moving the harness or clearing codes before capturing the original evidence.
Replacing a part without repeating the test.

PREPARE THE TEST

✓ Identify Hall, inductive or other sensor type✓ Verify reference, ground and signal pins✓ Select DC coupling for Hall; evaluate inductive sensors around their own reference✓ Obtain correct engine/variant reference data

STEP-BY-STEP PROCEDURE

Backprobe CKP and CMP signal circuits without disturbing connector tension.
Choose voltage ranges appropriate to each sensor type and a timebase showing at least two complete engine cycles.
Crank or run the engine at a stable speed and capture both channels simultaneously.
Inspect each trace for correct amplitude, clean switching, missing-tooth/index features and intermittent dropouts.
Locate the specified crank feature and compare its position to the cam edge or window.
Repeat at the operating condition that causes the fault. Do not declare jumped timing without a verified, application-specific known-good relationship.

WHAT THIS TEST CANNOT PROVE

Correlation changes with engine family, reluctor design and commanded cam position. A generic drawing cannot prove tooth alignment.

⚠ SAFETY / CONNECTION CAUTION

Keep leads clear of belts and the crank pulley. Do not resistance-test an active Hall sensor unless the service procedure specifically directs it.

STOP BEFORE CONDEMNING THE PART

Repeat the capture, verify the circuit under load and use vehicle-specific specifications. Follow with the most direct confirmation test indicated by the evidence.

NEXT QUICK TEST / SWEEPSensor Sweep + Dropout→