Powertrain Controls - ECM/PCM

DTC 19 Intermittent 7X Reference Circuit:

Ignition And Fuel System Schematic:

CIRCUIT DESCRIPTION
The crankshaft position sensor sends a reference signal to the Powertrain Control Module (PCM) seven times per revolution to indicate crankshaft position and RPM. The PCM can determine when to pulse the ignition coils and control ignition timing based on this information. This signal, is called the 7X reference because it occurs seven times per revolution. The seventh pulse is the sync pulse and is used for crankshaft position reference. The PCM applies 12 volts to terminal "J1-14" through CKT 1867 to crankshaft position sensor terminal "C".

DIAGNOSTIC TROUBLE CODE (DTC) 19 WILL SET WHEN
The PCM sees 15 resync pulses within 4 minutes and 16 seconds.

ACTION TAKEN (PCM WILL DEFAULT TO)
The Malfunction Indicator lamp (MIL) will illuminate, and the cooling fan will enable.

DTC CHART TEST DESCRIPTION
Number(s) below refer to circled number(s) on the diagnostic chart.

1. This determines if the PCM recognizes a problem.
2. When a 7X resync occurs, engine stumble may also occur. If a component connection or circuitry is at fault, engine stumble may be induced by wiggling the circuit or connection. This step determines if a component connection or circuit is at fault.
3. Operating faulty non-engine related electronic components may emit Electromagnetic Interference (EMI) which may cause a 7X resync. This step determines if the non-engine related component is at fault.

DIAGNOSTIC AIDS
^ An intermittent may be caused by a poor connection, rubbed through wire insulation, or a severed wire inside the insulation. Inspect PCM harness connector terminal "J1-17" and 1CM connector terminal "A" for proper mating, improperly formed or damaged terminals, or damaged harness.
^ An intermittent can also be the result of a defective reluctor wheel. Remove crankshaft sensor and inspect reluctor wheel through sensor mount hole. Check for porosity and condition of wheel.
^ If complaint was "Cranks But Will Not Run," DTC 19 may be set when engine start is attempted more than 15 times and ignition is not turned "OFF" between attempts.