Circuit Description
Each ignition coil supplies secondary voltage to a pair of spark plugs. This is called a waste spark ignition system. The engine control module (ECM) supplies ignition control (IC) signals to the ignition control module (ICM). The ICM fires the correct ignition coil at the correct time based on the IC signals. The ICM detects if cylinder 1 or cylinder 3 is on the compression stroke by sensing the secondary voltage and polarity of each side of the ignition coil. The higher voltage is on the compressing cylinder. The ICM provides a synthesized cam signal to the ECM based on these inputs. This is called compression sense ignition. The ECM uses the cam signals to synchronize fuel injection. This system consists of the following circuits:
| • | The ignition 1 voltage circuit |
| • | The ground circuit |
| • | The camshaft position (CMP) sensor signal circuit |
| • | The IC timing control B 2/3 circuit |
| • | The IC timing control 1/4 circuit |
Diagnostic Aids
| • | The following conditions may cause an engine cranks but won't start symptom: |
| - | Crankshaft reluctor wheel damage or improper installation |
| - | The sensor is coming in contact with the reluctor wheel |
| - | Foreign material passing between the sensor and the reluctor wheel |
| - | If the crankshaft rotates backwards, this symptom may occur. This condition is only with vehicles equipped with a manual transmission. This condition can occur when a vehicle is on an incline and the clutch is released and an engine stall occurs. |
| • | Excess crankshaft endplay will cause the CKP sensor reluctor wheel to move out of alignment with the CKP sensor. This could result in any of the following conditions: |
| - | A no start |
| - | A start and stall |
| - | Erratic performance |
| • | An improperly installed crankshaft could cause excess crankshaft endplay. |
| • | For an intermittent, refer to Intermittent Conditions . |
Step | Action | Values | Yes | No | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics Connector End View Reference: Engine Controls Connector End Views or Engine Control Module Connector End Views | ||||||||||||
1 | Did you perform the Diagnostic System Check-Engine Controls? | -- | Go to Step 2 | |||||||||
2 | Attempt to start the engine. Does the engine start and run. | -- | Go to Step 11 | Go to Step 3 | ||||||||
3 |
Does the CMP Resync counter increment? | -- | Go to Step 7 | Go to Step 4 | ||||||||
4 |
Is the resistance within the specified range? | 500-900ohms | Go to Step 20 | Go to Step 5 | ||||||||
5 | Test the signal 1 circuit of the CKP for the following conditions:
Did you find and correct the condition? | -- | Go to Step 23 | Go to Step 6 | ||||||||
6 | Test the low reference circuit for the following conditions:
Did you find and correct the condition? | -- | Go to Step 23 | Go to Step 12 | ||||||||
7 |
Does the voltage measure within the specified range? | 11-13 V | Go to Step 9 | Go to Step 8 | ||||||||
8 | Measure the voltage between the ignition 1 voltage circuit and a good ground with a DMM. Does the voltage measure within the specified range? | 11-13 V | Go to Step 17 | Go to Step 11 | ||||||||
9 |
Is the resistance less than the specified value? | 3 ohms | Go to Step 10 | Go to Step 17 | ||||||||
10 |
Does the voltage measure within the specified value? | 11-13 V | Go to Step 11 | Go to Step 13 | ||||||||
11 |
Does the test lamp flash on both coil control circuits during cranking? | -- | Go to Step 22 | Go to Step 13 | ||||||||
12 | Test for an intermittent or poor connection at the ECM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 23 | Go to Step 14 | ||||||||
13 | Test for an intermittent or poor connection at the harness and interconnect of the ICM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 23 | Go to Step 21 | ||||||||
14 | Test for an intermittent or poor connection at the CKP sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 23 | Go to Step 15 | ||||||||
15 |
Did you find and correct the condition? | -- | Go to Step 23 | Go to Step 18 | ||||||||
16 | Inspect the reluctor wheel for physical damage or looseness. Refer to Diagnostic Aids and Crankshaft and Bearing Cleaning and Inspection in Engine Mechanical. Did you find and correct the condition? | -- | Go to Step 23 | Go to Step 19 | ||||||||
17 | Repair the ignition 1 voltage circuit for one of the following conditions:
Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 23 | -- | ||||||||
18 | Repair the open in the ICM ground circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 23 | -- | ||||||||
19 | Replace the CKP sensor. Refer to Crankshaft Position Sensor Replacement . Did you complete the replacement? | -- | Go to Step 23 | -- | ||||||||
20 | Replace the ECM. Refer to Engine Control Module Replacement . Did you complete the replacement? | -- | Go to Step 23 | -- | ||||||||
21 | Replace the ICM. Refer to Ignition Control Module Replacement . Did you complete the replacement? | -- | Go to Step 23 | -- | ||||||||
22 | Replace the ignition coil housing. Refer to Ignition Coil Housing Replacement . Did you complete the replacement? | -- | Go to Step 23 | -- | ||||||||
23 | Attempt to start the engine. Does the engine start and continue to run? | -- | Go to Step 24 | Go to Step 2 | ||||||||
24 |
Are there any DTCs that have not been diagnosed? | -- | System OK | |||||||||
