Engine Cranks, But Will Not Run

Chart A-3 Engine Cranks But Will Not Run:

CIRCUIT DESCRIPTION
This chart assumes that battery condition and engine cranking speed are OK, and there is adequate fuel in the tank.

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

1. A Malfunction Indicator Lamp (MIL) (Service Engine Soon) "ON" is a basic test to determine if there is a 12 volts supply and ignition 12 volts to Powertrain Control Module (PCM). No Diagnostic Trouble Code (DTC) may be due to an PCM problem. If Throttle Position (TP) sensor is over 2.5 volts, the engine may be in the clear flood mode which will cause starting problems. The engine will not start without reference pulses and therefore the Tech 1 scanner (or equivalent) scan tool should read RPM (reference) during crank.

2. For the first two seconds with ignition "ON," or whenever reference pulses are being received, Tech 1 scanner should indicate fuel pump circuit voltage (8 to 12 volts).

3. Because the direct ignition system uses two plugs and wires to complete the circuit of each coil, the opposite spark should be left connected. If RPM was indicated during crank, the ignition control module is receiving a crank signal, but no spark at this test indicates the ignition module is not triggering the coils.

4. This test will determine if there is B+ battery voltage at the injectors. The injectors are powered by a 15 amp fuse located in the right side underhood electrical center (#1).

5. This test will determine if the ignition control module is not triggering the problem coil or if the tested coil is at fault. This test could also be performed by using another known good coil.

6. This test will determine if the ignition control module is not generating the reference pulse or if the wiring or PCM are at fault. By touching and removing a test light to 12 volts on CKT 430, a reference pulse should be generated. If RPM is indicated, the PCM and Wiring are OK.

DIAGNOSTIC AIDS
The PCM will disable injector drivers not receiving proper current while cranking the engine. The injector drivers will remain disabled until either the ignition key is cycled "OFF" for 10 seconds, or Tech 1 scanner is used to reset the injector fault.

Remember to use "INJ FAULT RS" on Tech 1 scanner each time the test light is moved to the next injector driver circuit to be tested.