GM Service Manual Online
For 1990-2009 cars only

Circuit Description

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

    • The ignition control (IC) timing signal
    • The IC timing control
    • The low resolution engine speed signal
    • The medium resolution engine signal
    • The camshaft position signal
    • The low reference

The ICM sends 3X signals to the PCM, and controls the timing advance during engine cranking. The timing advance changes to PCM control after the following actions occur:

    • The PCM receives the second 3X signal
    • The PCM applies 5 volts to the ignition control (IC) timing signal circuit.

The ICM monitors the CKP sync signal when the engine is cranking. The CKP sync signal is passed from the CKP sensor to the ICM on the CKP sensor 2 signal circuit. The CKP sync signal is used to determine the correct cylinder pair and initiate the ignition coil firing sequence. The 18X reference pulses are passed from the CKP sensor to the ICM on the CKP sensor 1 circuit. The 18X reference pulses are used for fuel injection and ignition control. After the ICM receives both signals, the ICM passes the 18X and 3X reference signals to the PCM. The CMP and the CKP sensors share a 12 volt reference and low reference circuit. The CKP sensor consists of the following circuits:

    • A 12 volt reference
    • A low reference
    • A CKP sensor 1 signal
    • A CKP sensor 2 signal

Conditions for Running the DTC

The engine is running.

Conditions for Setting the DTC

    • The powertrain control module (PCM) detects an open circuit in the IC signal circuit.
    • The condition is present for 300 3X 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 .

DTC P1352 - IC Signal Circuit Open

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 data for the DTC.
  2. Turn OFF the ignition for 30 seconds.
  3. Start the engine.
  4. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text, or as close to the Freeze Frame/Failure Records data that you observed.

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 connected to 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. Refer to Circuit Testing in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 6

Go to Step 7

6

  1. Turn OFF the ignition.
  2. Connect a DMM between the IC circuit and 3X LOW reference circuits.
  3. Turn ON the ignition.
  4. Probe the IC signal circuit with a test lamp connected to battery positive voltage.

Does the voltage measure within the specified range?

150-250 mV

Go to Step 8

Go to Step 7

7

  1. Turn OFF the ignition.
  2. Leave the PCM disconnected.
  3. Disconnect the ignition control 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 ignition control (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 OFF the ignition 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 13

Go to Step 2

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