System Description
This system includes the crankshaft position (CKP) sensor, the camshaft position (CMP) sensor, the ignition coil with the ignition control module (ICM), the secondary wires, the spark plugs, and the circuit conductors and connectors.
The powertrain control module (PCM) controls the ignition system. The PCM monitors the input signals from various engine sensors. The PCM controls the dwell of the ignition primary coil, computes the desired spark timing and firing of the ignition system via an ignition control (IC) timing control circuit to the ignition control module.
The distributor ignition (DI) system diagnostic table assumes the following conditions:
| • | The battery is fully charged. |
| • | There is adequate fuel in the fuel tank. |
| • | The fuel delivery system is functional. |
Diagnostic Aids
Engine mechanical conditions may prevent the distributor from rotating. Inspect the following conditions if the distributor rotor does not rotate:
| • | A broken distributor drive shaft |
| • | A worn or broken distributor drive gear |
| • | A worn or broken camshaft timing chain and gears |
An intermittent may be caused by a poor connection, rubbed through wire insulation, or a wire broken inside the insulation. Refer to Testing for Intermittent Conditions and Poor Connections . If a repair is necessary, refer to Wiring Repairs .
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
This step tests for a CKP signal to the PCM.
-
This step tests for an internally shorted CMP sensor.
-
This step tests for spark output at more than one spark plug wire. The J 26792 Spark Plug Tester requires a minimum of 25,000 volts to operate.
-
This step determines if spark is being delivered to the distributor cap.
-
This step tests if the PCM is providing a timing control signal to the ICM.
-
This step tests for a basic engine mechanical condition.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics Connector End View Reference: Engine Controls Connector End Views or Powertrain Control Module Connector End Views | ||||
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | |
2 | Test the fuse which supplies the ignition 1 voltage to the ignition coil assembly and the ignition control module (ICM). Refer to Circuit Protection - Fuses . Is the fuse open? | -- | Go to Step 32 | Go to Step 3 |
Is the engine speed parameter more than the specified value? | 125 RPM | Go to Step 9 | Go to Step 4 | |
Does the engine start and continue to run? | -- | Go to Step 26 | Go to Step 5 | |
5 |
Is the voltage equal the specified value? | B+ | Go to Step 6 | Go to Step 8 |
6 |
Is the voltage equal the specified value? | B+ | Go to Step 27 | Go to Step 7 |
7 |
Did you find and correct the condition? | -- | Go to Step 50 | Go to Step 8 |
8 |
Did you find and correct the condition? | -- | Go to Step 50 | Go to Step 30 |
Important: A few sparks then nothing is considered no spark. Does multiple spark events occur on both spark plug wires? | -- | Go to Step 31 | Go to Step 10 | |
Does multiple spark events occur? | -- | Go to Step 21 | Go to Step 11 | |
11 |
Is the resistance less than the specified value? | 1,000 ohms/ft | Go to Step 12 | Go to Step 44 |
12 |
Does the test lamp flash while cranking the engine? | -- | Go to Step 15 | Go to Step 13 |
13 |
Does the test lamp illuminate? | -- | Go to Step 14 | Go to Step 16 |
14 |
Does the test lamp illuminate? | -- | Go to Step 40 | Go to Step 47 |
15 |
Is the voltage more than the specified value? | 10 V | Go to Step 29 | Go to Step 33 |
16 |
Does the test lamp illuminate? | -- | Go to Step 39 | Go to Step 17 |
17 |
Did you find and correct the condition? | -- | Go to Step 50 | Go to Step 18 |
18 |
Is the voltage more than the specified value? | 10 V | Go to Step 19 | Go to Step 34 |
19 | Probe the ground circuit of the ICM with a test lamp that is connected to battery voltage. Does the test lamp illuminate? | -- | Go to Step 20 | Go to Step 35 |
Is the voltage within the specified value? | 1-4 V | Go to Step 28 | Go to Step 23 | |
Did you find a condition? | -- | Go to Step 46 | Go to Step 22 | |
22 |
Does the distributor rotor rotate when the engine cranks? | -- | Go to Step 45 | Go to Diagnostic Aids |
23 |
Did you find and correct the condition? | -- | Go to Step 50 | Go to Step 24 |
24 | Probe the IC timing control circuit of the PCM with a test lamp that is connected to battery voltage. Refer to Probing Electrical Connectors . Does the test lamp illuminate? | -- | Go to Step 37 | Go to Step 25 |
25 |
Does the test lamp illuminate? | -- | Go to Step 38 | Go to Step 30 |
26 | Test for an intermittent and for a poor connection at the CMP sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | -- | Go to Step 50 | Go to Step 41 |
27 | Test for an intermittent and for a poor connection at the CKP sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | -- | Go to Step 50 | Go to Step 42 |
28 | Test for an intermittent and for a poor connection at the ICM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | -- | Go to Step 50 | Go to Step 47 |
29 | Test for an intermittent and for a poor connection at the ignition coil. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | -- | Go to Step 50 | Go to Step 43 |
30 | Test for an intermittent and for a poor connection at the PCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | -- | Go to Step 50 | Go to Step 48 |
31 | Inspect the spark plugs for damage or contamination. Refer to Spark Plug Replacement and Spark Plug Inspection . Did you find and correct the condition? | -- | Go to Step 50 | Go to Testing for Intermittent Conditions and Poor Connections |
32 | Repair the short to ground in the ignition 1 voltage circuit. Refer to Circuit Testing and Wiring Repairs . Did you complete the repair? | -- | Go to Step 49 | -- |
33 | Repair the open or the high resistance in the ignition 1 voltage circuit between the underhood fuse block and the ignition coil. Refer to Wiring Repairs . Did you complete the repair? | -- | Go to Step 50 | -- |
34 | Repair the open or the high resistance in the ignition 1 voltage circuit between the underhood fuse block and the ICM. Did you complete the repair? | -- | Go to Step 50 | -- |
35 | Repair the open or the high resistance in the ground circuit of the ICM. Refer to Wiring Repairs . Did you complete the repair? | -- | Go to Step 50 | -- |
36 | Repair the open or the high resistance in the IC timing control circuit. Refer to Wiring Repairs . Did you complete the repair? | -- | Go to Step 50 | -- |
37 | Repair the short to ground in the IC timing control circuit. Refer to Wiring Repairs . Did you complete the repair? | -- | Go to Step 50 | -- |
38 | Repair the short to voltage in the IC timing control circuit. Refer to Wiring Repairs . Did you complete the repair? | -- | Go to Step 50 | -- |
39 | Repair the short to voltage in the ignition coil control circuit. Refer to Wiring Repairs . Did you complete the repair? | -- | Go to Step 50 | -- |
40 | Repair the short to ground in the ignition coil control circuit. Refer to Wiring Repairs . Did you complete the repair? | -- | Go to Step 50 | -- |
41 | Replace the CMP sensor. Refer to Camshaft Position Sensor Replacement . Did you complete the replacement? | -- | Go to Step 50 | -- |
42 | Replace the CKP sensor. Refer to Crankshaft Position Sensor Replacement . Did you complete the replacement? | -- | Go to Step 50 | -- |
43 | Replace the ignition coil. Refer to Ignition Coil Replacement . Did you complete the replacement? | -- | Go to Step 50 | -- |
44 | Replace the ignition coil wire. Refer to Spark Plug Wire Replacement . Did you complete the replacement? | -- | Go to Step 50 | -- |
45 | Replace the distributor rotor. Refer to Distributor Overhaul . Did you complete the replacement? | -- | Go to Step 50 | -- |
46 | Replace the distributor cap. Refer to Distributor Overhaul . Did you complete the replacement? | -- | Go to Step 50 | -- |
47 | Replace the ICM. Refer to Ignition Control Module Replacement . Did you complete the replacement? | -- | Go to Step 50 | -- |
48 | Replace the PCM. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement? | -- | Go to Step 50 | -- |
49 | Replace the fuse. Did you complete the replacement? | -- | Go to Step 50 | -- |
50 |
Does the vehicle operate normally with no malfunction indicator lamp (MIL) illumination and no stored DTCs? | -- | System OK | |
