Circuit Description
The Ignition System uses a ignition coil assembly for each bank. Each ignition coil assembly consist of 3 ignition coils. The ignition coil assemblies consist of the following circuits:
| • | An ignition voltage circuit |
| • | A ground circuit |
| • | An ignition control (IC) circuit for each ignition coil |
The ignition coil assemblies are mounted in the center of each camshaft cover with short boots connecting the coils to the spark plugs. The engine control module (ECM) primarily uses engine speed and position information from the crankshaft position (CKP) sensor and the camshaft position (CMP) sensor to control the sequence, dwell, and timing of the spark. The ECM can command each ignition coil ON/OFF by grounding the IC circuit of the ignition coil. The IC circuits are pulse width modulated (PWM) in order to precisely control the spark events.
Step | Action | Values | Yes | No | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics Connector End View Reference: Engine Control Module Connector End Views or Engine Controls 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 idle? | -- | Go to Step 3 | Go to Step 6 | ||||||
3 |
Did you have spark on all cylinders? | -- | Go to Step 4 | Go to Step 10 | ||||||
4 | Does the spark tester indicate a bright blue spark on all cylinders? | -- | Go to Step 5 | Go to Step 15 | ||||||
5 |
Are the spark plugs in good condition? | -- | System OK | Go to Step 21 | ||||||
6 |
Does the test lamp illuminate? | -- | Go to Step 7 | Go to Step 17 | ||||||
7 | Connect a test lamp from the ignition voltage circuit to the ground circuit of the ignition coil assembly. Does the test lamp illuminate? | -- | Go to Step 8 | Go to Step 18 | ||||||
8 |
Is the resistance less than the specified value? | 3 ohms | Go to Step 9 | Go to Step 19 | ||||||
9 | Measure the resistance of ground circuit of the ignition coil assembly from the harness connector of the ignition coil assembly to a good ground with a DMM. Is the resistance less than the specified value? | 3 ohms | Go to Step 15 | Go to Step 20 | ||||||
10 |
Important: If using a different test lamp, the bulb resistance needs to be 4 ohms or less. Does the test lamp flash? | -- | Go to Step 12 | Go to Step 11 | ||||||
11 | Does the test lamp remain ON? | -- | Go to Step 13 | Go to Step 14 | ||||||
12 |
Does the test lamp illuminate with same brightness for both circuits? | -- | Go to Step 15 | Go to Step 14 | ||||||
13 | Test the IC circuit of the inoperative ignition coil for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 24 | Go to Step 16 | ||||||
14 | Test the IC circuit of the inoperative ignition coil for one of the following conditions:
Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 24 | Go to Step 16 | ||||||
15 | Test for shorted terminals or a poor connection at the ignition coil assembly. 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 24 | Go to Step 22 | ||||||
16 | Test for shorted terminals or a poor connection at the engine control module (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 24 | Go to Step 23 | ||||||
17 | Repair an open or a short to ground in the ignition voltage circuit of the ignition coil assembly. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 24 | -- | ||||||
18 | Repair an open in the ground circuit of the ignition coil assembly. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 24 | -- | ||||||
19 | Repair the high resistance in the ignition voltage circuit of the ignition coil assembly. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 24 | -- | ||||||
20 | Repair the high resistance in the ground circuit of the ignition coil assembly. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 24 | -- | ||||||
21 | Replace the spark plugs. Refer to Spark Plug Replacement . Did you complete the replacement? | -- | Go to Step 24 | -- | ||||||
22 | Replace the ignition coil assembly. Refer to Ignition Coil Replacement - Bank 1 or Ignition Coil Replacement - Bank 2 . Did you complete the replacement? | -- | Go to Step 24 | -- | ||||||
23 | Replace the ECM. Refer to Engine Control Module Replacement . Did you complete the replacement? | -- | Go to Step 24 | -- | ||||||
24 |
Does the vehicle operate normally? | -- | System OK | Go to Step 2 | ||||||
