Crank/Cam Correlation Quick Reference for No-Start
No-start sync issues are sensing-first diagnostics. Post-transmission or front-cover service sync faults and heat-soak intermittents are the most documented patterns. The FSM blocks timing teardown until signals are proven.
Fault Overview
Crank/cam correlation quick reference is a process page for no-start or stall where CKP/CMP correlation or signal integrity is suspect. Failed CKP or CMP, tone ring damage, harness intermittents, incorrect sensor install after service, and timing component issues are the primary causes. Post-transmission or front-cover service sync faults and heat-soak intermittents are documented patterns. Timing teardown for a sensor or harness fault is the most documented and most expensive misdiagnosis pattern.
Engine & Platform Coverage
Symptoms
- •Crank cam correlation no start
- •Sync loss diesel
- •Intermittent stall cam crank
- •No RPM while cranking
- •Injector disable events from sync loss
Possible Causes
- 1.Failed CKP or CMP — failed CKP or CMP sensor producing no or incorrect signal
- 2.Tone ring damage — tone ring damage producing incorrect signal pattern
- 3.Harness intermittents — harness intermittents producing intermittent signal
- 4.Incorrect sensor install after service — incorrect sensor install after service producing incorrect signal
- 5.Timing component issues — timing component issues producing correlation fault (less common than sensing)
Diagnostic Flow — FSM Sequence
AI Diesel Tech enforces this evidence-gate sequence. Each gate must pass before advancing.
4 steps locked behind Technician Mode- 1Step 1 — Cranking RPM Present?: Confirm cranking RPM is present. No RPM while cranking usually equals a CKP problem. A cranking RPM that is present but incorrect or erratic confirms a CKP signal quality fault. A cranking RPM that is absent confirms a CKP circuit or sensor fault.
- 2Step 2 — CKP Pattern: Evaluate the CKP pattern. Confirm the CKP signal is present and correct during cranking. Post-transmission or front-cover service sync faults are a documented pattern — always inspect the CKP sensor and circuit after any recent transmission or front-cover service. Verify the CKP sensor is correctly installed.
- 3Step 3 — CMP Pattern: Evaluate the CMP pattern. Confirm the CMP signal is present and correct during cranking. A CMP signal that is present without a CKP signal or with a mismatched phase is a correlation path fault.
- 4Step 4 — Correlation Phase: Evaluate the correlation phase between CKP and CMP signals. A mismatched phase between CKP and CMP confirms a correlation fault. A correlation fault with correct individual signals may indicate a timing component issue.
- 5Step 5 — Mechanical Timing Only After Clean Signals: Evaluate mechanical timing only after clean signals are confirmed. Timing teardown for a sensor or harness fault is the most documented and most expensive misdiagnosis pattern. Confirm CKP and CMP signal integrity before any mechanical timing assessment.
Unlock the full evidence-gated diagnostic sequence, DVOM test steps, and repair procedures in Technician Mode.
Repair Steps
3 steps locked- 1Replace CKP sensor if signal fault is confirmed.
- 2Replace CMP sensor if signal fault is confirmed.
- 3Repair harness if intermittent is confirmed.
- 4Replace tone ring if damage is confirmed.
- 5Evaluate mechanical timing only after clean signals are confirmed.
Unlock full diagnostic steps, DVOM tests, and repair procedures.
Full Diagnostic Access
Verification steps, preventative measures, severity guidance, and legacy comparison are available in Technician Mode.
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Summary
No-start sync issues are sensing-first diagnostics. The AI Diesel Tech FSM blocks timing teardown until signals are proven.