Chart A-3 Engine Cranks But Won't Run (VIN L)
Circuit Description:
The C(3)I uses a waste spark method of spark distribution. In this type of ignition system the ignition module triggers the #1/4 coil pair resulting in both #1 and #4 spark plugs firing at the same time. #1 cylinder is on the compression stroke at the same time #4 is on the exhaust stroke, resulting in a lower energy requirement to fire #4 spark plug. This leaves the remaining high voltage to fire #1 spark plug. This Simultaneous Fuel Injection type of fuel delivery system utilizes 2 injector driver circuits in parallel, to activate the 6 individual fuel injectors. The ECM activates all 6 injectors simultaneously (all at one time).
CHART A-3(Page 1 of 3) ENGINE CRANKS BUT WON'T RUN 1986-1987 3.0L (VIN L):
Test Description: Numbers below refer to circled numbers on the diagnostic chart.
1. This step verifies that "SES" light operation, TPS and coolant sensor signals are normal. A blinking injector test light verifies that the ECM is monitoring the C(3)I reference signal and attempting to activate the injectors.
2. Both the "Sync-Pulse" and crank signals have been verified, as is evidenced by the blinking injector test light. A fuel pressure test at this point will separate the diagnostic path into either a fuel related fault or ignition system malfunction.
3. The 3 terminal injector harness connector must be disconnected to avoid flooding of the engine and fouling of the spark plugs.
By testing for spark on plug leads 1, 3 and 5, each ignition coil's ability to produce at least 25,000 volts is verified.
4. By testing the problem coil's control circuit with a test light, a determination can be made as to the problem coil being faulty or the module's internal driver for that coil being the source of the complaint.
5. An injector with a resistance value of less than 10 ohms (shorted) must be replaced.
6. Tests for battery voltage on CKT 939. If voltage was present, the "light off" test result was caused by no activation pulse reaching the injector connector from the ECM.
CHART A-3
(Page 2 of 3)
ENGINE CRANKS BUT WON'T RUN
Circuit Description: 1986-1987 3.0L (VIN L) For synchronization of spark plug firing, a "Sync-Pulse" is created by the combination sensor "hall effect" switch, The sensor sends the "Sync-Pulse" to the ignition module, when cylinders #1 and #4 are 25~ after top dead center. This signal is used to start the correct sequence of coil firing with the #3/6 ignition coil. The crank signal portion of the combination sensor sends a signal to the ignition module for coil activation and then to the ECM for reference rpm and crankshaft position. There are three windows in a disc (interruptor) which is mounted to the harmonic balancer. As these windows pass through the slot in the sensor, the next coil is triggered.
CHART A-3(Page 2 of 3)ENGINE CRANKS BUT WON'T RUN 1986-1987 3.0L (VIN L):
Test Description: Numbers below refer to circled numbers on the diagnostic chart.
7. Verifies ignition feed voltage at terminal "P" of the C(3)I module. Less than battery voltage would be an indication of a CKT 439 fault.
8. The test light to 12 volts simulates a reference signal to the ECM which will result in an injector test light blink. This will validate CKT 430, the ECM and the injector driver circuit are all OK.
9. Jumping the combination sensor harness terminals "B" and "C" together simulates a "SyncPulse" signal to the C(3)I module.
Then, by repeatedly jumping the combination sensor harness terminals "B" and "D" together, a crank signal is simulated, which should result in the injector test light blinking.
10. Verifies a proper "Sync-Pulse" signal circuit voltage of 6 to 9 volts and a good ground from the C(3)I module to terminal "B" of the sensor connector.
11. Determines if reason for incorrect voltage reading was due to a fault in CKT 972, an open in CKT 952, or a faulty C(3)I module. If the C(3)I module was faulty, also verify that CKT 453 to ECM terminal "B3" is not open.
CHART A-3
(Page 3 of 3)
ENGINE CRANKS BUT WON'T RUN
Circuit Description: 1986-1987 3.0L (VIN L) For synchronization of spark plug firing, a "Sync-Pulse" is created by the combination sensor "hall effect" switch. The sensor sends the "Sync-Pulse" to the ignition module when cylinders #1 and #4 .are 25~ after top dead center. This signal is used to start the correct sequence of coil firing with the #3/6 ignition coil. The crank signal portion of the combination sensor sends a signal to the ignition module for coil activation and then to the ECM for reference rpm and crankshaft position. There are three windows in a disc (interruptor) which is mounted to the harmonic balancer. As these windows pass through the slot in the sensor, the next coil is triggered.
CHART A-3(Page 3 of 3)ENGINE CRANKS BUT WON'T RUN 1986-1987 3.0L (VIN L):
Test Description: Numbers below refer to circled numbers on the diagnostic chart.
12. Verifies a proper Crank signal circuit voltage of 7 to 9 volts and a good ground from the C(3)I module to terminal "B" of the sensor connector.
13. Determines if reason for incorrect voltage reading was due to a fault in CKT 971, an open in CKT 952 or a faulty C(3)I module.