FREE REPAIR MANUALS & LABOR GUIDES 1982-2013 Vehicles
Courtesy of Operation CHARM: Car repair manuals for everyone.

Engine Start-Up (Cranking)



This is an OPEN LOOP mode.

When the starter motor is engaged, the PCM receives input from:


- Battery voltage

- Crankshaft position (CKP) sensor

- Engine coolant temperature (ECT) sensor

- Intake air temperature (IAT) sensor

- Throttle position sensor (TPS)

- Camshaft position (CMP) sensor

- Starter relay

Based on these inputs the PCM will:

- Monitor crankshaft and camshaft position sensor. If signals are not received within 1 second, the PCM will shut down the ASD and fuel pump relays.

- Supply the injectors with a ground path, firing all injectors until the PCM determines crankshaft position.

- Fire injectors in sequence, once PCM has determined crankshaft position.

- Compare 0 RPM MAP sensor reading to idle speed MAP sensor reading. If the PCM does not detect a minimum difference it will set a Diagnostic Trouble Code.

- Determine proper ignition timing.