A no-start diagnosis moves quickly when cranking speed, module communication, spark or ignition command, injector command, and mechanical timing are checked in order.
Why this matters
Cranking proves the starter can rotate the engine; it does not prove the battery voltage is stable, the control modules are awake, or combustion inputs are present.
Evidence to capture first
- Battery voltage and cranking rpm
- Communication with the engine controller and immobilizer status
- A safe indication of spark or ignition command, injector pulse, and relative compression
A disciplined path
- Record all codes and scan-data values with the key on before extended cranking.
- Confirm the engine controller sees a plausible rpm signal while cranking.
- Check one missing combustion requirement at a time: air path, ignition, fueling command, then compression and timing.
- Use current model service information to interpret immobilizer and sync data rather than guessing from a warning lamp.
Decision point
The best next test is the one that divides the possibilities. If rpm is absent, investigate the speed-signal path; if rpm and command are present, move to delivery and mechanical integrity.
Source desk
Use current model-specific service information for specifications, connector locations, disabling procedures, and tightening values. The following public resources support the broader safety or system context used in this guide.
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