System Description
This system includes the distributor, the camshaft position (CMP) sensor , the ignition coil with the ignition control (IC) module, the secondary wires, the spark plugs, the knock sensors (KS), and the crankshaft position (CKP) sensor. The ignition system is controlled by the powertrain control module (PCM). The PCM monitors the information from various engine sensors, computes the desired spark timing, and controls the dwell and firing of the ignition coil via an IC line to the IC module.
Diagnostic Aids
Check the following when the distributor rotor does not rotate, while engine is cranking:
| • | A broken distributor drive shaft |
| • | A worn distributor drive gear or camshaft timing chain and gears |
An intermittent may be caused by any of the following conditions:
| • | A poor connection |
| • | Rubbed through wire insulation |
| • | A broken wire inside the insulation |
Thoroughly inspect any circuitry that is suspected of causing the intermittent complaint. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
If a repair is necessary, refer to Wiring Repairs or Connector Repairs in Wiring Systems.
Test Description
Important: The battery should be fully charged prior to any tests.
The numbers below refer to the step numbers on the diagnostic table.
-
This step checks for proper spark output. The spark test requires a minimum of 25,000 volts to operate. This check can be used in case of an ignition miss, because the system may provide enough voltage to run the engine but not enough to operate a spark plug under heavy load.
-
This test separates the distributor cap, rotor, and ignition wires from the ignition coil in order to help identify a secondary ignition system problem.
-
This test checks the ignition control module, connections, and wiring.
-
This test begins to determine if the PCM is providing a signal to the ignition control module. If the PCM is not providing a signal to the ignition control module, the problem exists between the ignition control module and the PCM.
-
This test checks for a basic engine mechanical problem.
Step | Action | Values | Yes | No | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
Schematic Reference:
| ||||||||||||
1 | Did you perform the Diagnostic System Check-Engine Controls ? | -- | ||||||||||
2 |
Does the scan tool display engine RPM? | -- | ||||||||||
Does spark occur on all cylinders? | -- | Go to Intermittent Conditions | ||||||||||
Does spark occur? | -- | |||||||||||
5 | Measure the coil wire resistance. Does the resistance measure approximately the specified value? | 1,000 ohms/ft | ||||||||||
Does the test lamp flash while cranking the engine? | -- | |||||||||||
7 |
Does the test lamp illuminate? | -- | ||||||||||
8 |
Does the voltage measure above the specified value? | 10.0 V | ||||||||||
9 |
Did you find the condition? | -- | ||||||||||
10 |
Does the voltage measure above the specified value? | 10.0 V | ||||||||||
11 | Probe the IC module harness connector ground circuit with a test lamp connected to battery positive voltage. Does the test lamp illuminate? | -- | ||||||||||
Does the voltage measure within the specified values? | 1.0-4.0 V | |||||||||||
13 |
Did you find any of these conditions? | -- | ||||||||||
Did the distributor rotor turn? | -- | |||||||||||
15 |
Did you find the condition? | -- | ||||||||||
16 | Probe the ignition timing control circuit at the PCM with a test lamp connected to battery voltage. Does the test lamp illuminate? | -- | ||||||||||
17 |
Does the test lamp illuminate? | -- | ||||||||||
18 |
Did you complete the repair? | -- | -- | |||||||||
19 |
Did you find and correct the condition? | -- | ||||||||||
20 |
Did you complete the repair? | -- | -- | |||||||||
21 | Check for a poor IC module connection. Did you find a problem? | -- | ||||||||||
22 | Check for a poor coil connection . Did you find a problem? | -- | ||||||||||
23 | Check for a poor PCM connection. Did you find a problem? | -- | ||||||||||
24 | Repair the open IC module ground circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | -- | |||||||||
25 | Repair the open ignition timing control circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | -- | |||||||||
26 | Repair the grounded ignition timing control circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | -- | |||||||||
27 | Repair the short to voltage in the ignition timing control circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | -- | |||||||||
28 | Repair the open or short to voltage in the coil driver circuit between the ignition coil and the IC module. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | -- | |||||||||
29 | Repair the short to ground in the coil driver circuit between the ignition coil and the IC module. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | -- | |||||||||
30 | Repair the circuit as necessary. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | -- | |||||||||
31 | Replace the ignition coil. Refer to Ignition Coil Replacement . Did you complete the replacement? | -- | -- | |||||||||
32 | Replace the coil wire. Refer to Spark Plug Wire Replacement t. Did you complete the replacement? | -- | -- | |||||||||
33 | Replace the distributor rotor. Refer to Distributor Overhaul . Did you complete the replacement? | -- | -- | |||||||||
34 | Replace the distributor cap. Refer to Distributor Overhaul . Did you complete the replacement? | -- | -- | |||||||||
35 | Replace the IC module. Refer to Ignition Control Module Replacement . Did you complete the replacement? | -- | -- | |||||||||
36 | Replace the PCM. Refer to Powertrain Control Module Replacement . Did you complete the replacement? | -- | -- | |||||||||
37 | Operate the vehicle within the conditions under which the original symptom was noted. Does the system now operate properly? | -- | System OK | |||||||||
