Circuit Description
The ignition system uses a ignition control module (ICM) for each bank. The ICM consist of a controller and ignition coils. The assemblies are mounted in the center of each camshaft cover, with short boots connecting the coils to the spark plugs. The ECM primarily uses engine speed and position information from the crankshaft (CKP) and camshaft position (CMP) sensors to control the sequence, dwell, and timing of the spark. The ECM can command each ignition coil ON/OFF by grounding the control circuit of the ignition coil. The control 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 4 | ||||||
3 |
Does the misfire counters indicate misfires for one cylinder? | -- | Go to Step 8 | Go to Step 4 | ||||||
4 |
Does the test lamp illuminate? | -- | Go to Step 5 | Go to Step 14 | ||||||
5 | Connect a test lamp from the ignition voltage circuit to the ground circuit of the ICM. Does the test lamp illuminate? | -- | Go to Step 6 | Go to Step 15 | ||||||
6 |
Is the resistance less than the specified value? | 3 ohms | Go to Step 7 | Go to Step 16 | ||||||
7 | Measure the resistance of ground circuit of the ICM from the harness connector of the ICM to a good ground with a DMM. Is the resistance less than the specified value? | 3 ohms | Go to Step 12 | Go to Step 17 | ||||||
8 |
Important: The fuel injector test lamp will be dim in brightness which is normal. If using a different fuel injector test lamp, bulb resistance needs to be 4 ohms or less. Does the fuel injector test lamp flash? | -- | Go to Step 12 | Go to Step 9 | ||||||
9 | Does the fuel injector test lamp remain ON steady? | -- | Go to Step 10 | Go to Step 11 | ||||||
10 | Test the control 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 20 | Go to Step 13 | ||||||
11 | Test the control 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 20 | Go to Step 13 | ||||||
12 | Test for shorted terminals or a poor connection at 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 20 | Go to Step 18 | ||||||
13 | 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 20 | Go to Step 19 | ||||||
14 | Repair an open or short to ground in the ignition voltage circuit of the ICM. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 20 | -- | ||||||
15 | Repair an open in the ground circuit of the ICM. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 20 | -- | ||||||
16 | Repair the high resistance in the ignition voltage circuit of the ICM. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 20 | -- | ||||||
17 | Repair the high resistance in the ground circuit of the ICM. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 20 | -- | ||||||
18 | Replace the ICM. Refer to Ignition Coil Module Replacement - Left Side or Ignition Coil Module Replacement - Right Side . Did you complete the replacement? | -- | Go to Step 20 | -- | ||||||
19 | Replace the ECM. Refer to Engine Control Module Replacement . Did you complete the replacement? | -- | Go to Step 20 | -- | ||||||
20 |
Does the vehicle operate normally? | -- | System OK | Go to Step 2 | ||||||
