Part 1 of 3
Chart A-3 - Part 1 Of 3:
Injector and Ignition Control:
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 MIL (Service Engine Soon) "ON" is a basic test to determine if there is a 12 volts supply and ignition 12 volts to ECM. No DLC may be due to an ECM problem and CHART A-2 will diagnose the ECM. If 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 (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, PPSW should indicate fuel pump circuit voltage (8 to 12 volts).
3. Because the electronic 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 control module is not triggering the coils.
4. This test will determine if there is B+ at the injectors. The injectors are powered by a 10 amp fuse located in the right side underhood electrical center.
5. This test will check the integrity of the ECM injector driver.
6. This test will determine if CKT 467 is open between the mini harness connector and the injectors.
7. 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.
8. This test will determine if the ignition control module is not generating the reference pulse or if the wiring or ECM 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 ECM and wiring are OK.