For 1990-2009 cars

### Circuit Description

The ignition control (IC) module has independent power and ground circuits. The circuits between the IC module and the powertrain control module (PCM) consist of the following circuits:

• | The IC timing signal

• | The IC timing control

• | The low-resolution engine speed signal

• | A low reference

The IC module sends 3 X signals to the PCM. The IC module controls the timing advance during engine cranking. The timing advance changes to PCM control after the following actions:

• | The PCM receives the second 3 X signal.

• | The PCM applies 5 volts to the IC timing signal circuit.

• | The timing advance switches to PCM control.

### Conditions for Running the DTC

The engine is running.

### Conditions for Setting the DTC

• | The PCM detects an open circuit in the IC signal circuit.

• | The condition is present for 300 3 X reference periods, 106 crankshaft revolutions.

### Action Taken When the DTC Sets

• | The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.

• | The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

### Conditions for Clearing the MIL/DTC

• | The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.

• | A current DTC, Last Test Failed, clears when the diagnostic runs and passes.

• | A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.

• | Clear the MIL and the DTC with a scan tool.

### Diagnostic Aids

The engine will start and may run in bypass mode timing.

If the condition is intermittent, refer to Intermittent Conditions .

Step | Action | Values | Yes | No
--- | --- | --- | --- | ---
Schematic Reference: Engine Controls Schematics
1 | Did you perform the Diagnostic System Check-Engine Controls? | -- | Go to Step 2 | Go to Diagnostic System Check - Engine Controls
2 |

1. Observe the Freeze Frame/Failure Records for the DTC.
2. Turn the ignition OFF for 30 seconds.
3. Start the engine.
4. Operate the vehicle within the Conditions for Running the DTC, or within the parameters that are observed in the Freeze Frame/Failure Records.

Does the DTC fail this ignition?

--

Go to Step 3

Go to Intermittent Conditions

3 |

1. Turn OFF the ignition.
2. Disconnect the PCM.
3. Turn ON the ignition.
4. Probe the low reference circuit with a test lamp that is connected to the battery positive voltage.

Does the test lamp illuminate?

--

Go to Step 6

Go to Step 4

4 | Inspect the low reference circuit for an open. Did you find and correct the condition? | -- | Go to Step 6 | Go to Step 5
5 | Inspect for poor connections at the IC module. Did you find and correct the condition? | -- | Go to Step 6 | Go to Step 7
6 |

1. Turn OFF the ignition.
2. Disconnect the PCM.
3. Connect the DMM between the IC and the low reference circuits.
4. Turn ON the ignition.
5. Probe the IC signal circuit with a test lamp that is connected to the battery positive voltage.

Does the resistance measure greater than the specified value?

5,000 ohms

Go to Step 8

Go to Step 7

7 |

1. Turn OFF the ignition.
2. Do NOT reconnect the PCM.
3. Disconnect the IC module connector.
4. Test for an open in the IC signal circuit. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 12

Go to Step 9

8 | Inspect for poor terminal connections at the PCM. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 11
9 | Inspect for poor terminal connections at the IC module. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 10
10 | Replace the IC module. Refer to Ignition Control Module Replacement . Did you complete the replacement? | -- | Go to Step 12 | --
11 | Replace the PCM. Refer to Powertrain Control Module Replacement . Did you complete the replacement? | -- | Go to Step 12 | --
12 |

1. Use the scan tool in order to clear the DTCs.
2. Turn the ignition OFF for 30 seconds.
3. Start the engine.
4. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC run and pass?

--

Go to Step 3

Go to Step 13

13 | With a scan tool, observe the stored information, Capture Info. Does the scan tool display any DTCs that you have not diagnosed? | -- | Go to Diagnostic Trouble Code (DTC) List | System OK