Part 1 of 2

Chart A-3 Part 1 Of 2:

Chart A-3 Wiring Diagram:

CIRCUIT DESCRIPTION:

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

TEST DESCRIPTION: Numbers below refer to circled numbers on the diagnostic chart.

1. A "SERVICE ENGINE SOON" (SES) light "ON" is a basic test to determine if there is a 12 volts supply and ignition 12 volts to Electronic Control Module (ECM). No Assembly Line Diagnostic Link (ALDL) may be due to an ECM problem and CHART A-2 will diagnose the ECM. If Throttle Position Sensor (TPS) 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 "Scan" should read rpm (reference) during crank.

2. No spark may be caused by one of several components related to the ignition system. CHART C-4 will address all problems related to the causes of a no spark condition.

3. The test light should blink, indicating the ECM is controlling the injectors OK. How bright the light blinks is not important. However, the test light should be a J-34730-3 or equivalent.

4. Use fuel pressure gauge J-34730-1 or equivalent. Wrap a shop towel around the fuel pressure tap to absorb any small amount of fuel leakage that may occur when installing the gauge.

DIAGNOSTIC AIDS:

An EGR valve sticking open can cause a low air/fuel ratio during cranking. Unless engine enters "Clear Flood" at the first indication of a flooding condition, it can result in a no start. Check for fouled plugs. Water in fuel line can cause a no start in cold weather. Also check that injectors on both sides of engine will cause a test light to "blink." If not OK, check injector fuses. If above are all OK, for hard starting diagnosis, refer to Diagnosis By Symptom Testing and Inspection