DTC P1352 Ignition Bypass Circuit High Voltage. Buick GL7 (Export) 2000

For 1990-2009 cars

### Circuit Description

The ignition control module (ICM) sends the signals that the powertrain control module (PCM) requires for fuel control and spark advance calculations. At the start of engine crank, the ICM controls the spark advance. When the second 3X reference pulse is recognized by the PCM, the PCM applies 5 volts to the bypass circuit, commanding the ICM to switch the spark advance to PCM control. If the PCM detects an open in the bypass circuit, DTC P1352 will set. The engine will start and may run in Bypass mode timing.

### Conditions for Running the DTC

The engine is running.

### Conditions for Setting the DTC

• | The PCM detects an open circuit in the bypass circuit.

• | The condition is present for 300 3X reference periods (100 crankshaft revolutions).

### Action Taken When the DTC Sets

• | The PCM will illuminate the malfunction indicator lamp (MIL) during the second consecutive trip in which the diagnostic test has been run and failed.

• | The PCM will store conditions which were present when the DTC set as Freeze Frame/Failure Records data.

### Conditions for Clearing the MIL/DTC

• | The PCM will turn OFF the malfunction indicator lamp (MIL) during the third consecutive trip in which the diagnostic has run and passed.

• | The history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.

• | The DTC can be cleared by using a scan tool.

### Diagnostic Aids

Inspect for the following conditions:

• | A poor connection at the PCM. Inspect the harness connectors for the following conditions:

- | Backed-out terminals

- | Improper mating

- | Broken locks

- | Improperly formed or damaged terminals

- | Poor terminal-to-wire connection

• | A damaged harness. Inspect the wiring harness for damage. If the harness appears to be OK, disconnect the ICM, turn the ignition on, and observe a digital multimeter (DMM) connected between the IC circuit and B+ voltage while moving the connectors and the wiring harnesses related to the ICM. A change in voltage will indicate the location of the malfunction.

Reviewing the Failure Records vehicle mileage since the diagnostic test last failed may help determine how often the condition that caused the DTC to be set occurs. This may assist in diagnosing the condition.

#### DTC P1352 - Bypass Circuit Open

Step | Action | Values | Yes | No
--- | --- | --- | --- | ---
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | Go to Step 2 | Go to Powertrain On Board Diagnostic (OBD) System Check

2

1. Turn OFF the ignition switch.
2. Disconnect the PCM.
3. Connect a DMM between the IC circuit and the reference low circuit.
4. Turn ON the ignition switch.
5. Probe the Bypass circuit with a test lamp connected to B+ voltage.

Is the resistance more than the specified value?

5,000 ohms

Go to Step 4

Go to Step 3

3

1. Turn OFF the ignition switch.
2. Leave the PCM disconnected.
3. Disconnect the ICM.
4. Test for an open in the Bypass circuit.
5. If a problem is found, repair as necessary. Refer to Wiring Repairs in Wiring Systems.

Was a problem found?

--

Go to Step 8

Go to Step 5

4

1. Test for poor terminal connections at the PCM.
2. If a problem is found, repair as necessary. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

Was a problem found?

--

Go to Step 8

Go to Step 7

5

1. Test for poor terminal connections at the ICM.
2. If a problem is found, repair as necessary. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

Was a problem found?

--

Go to Step 8

Go to Step 6

6 | Replace the ignition control module. Is the action complete? | -- | Go to Step 8 | --
7 | Important: : The replacement PCM must be programmed. Replace the PCM. Refer to Powertrain Control Module Replacement/Programming . Is the action complete? | -- | Go to Step 8 | --

8

1. Review and record the scan tool Failure Records data.
2. Clear the DTCs.
3. Operate the vehicle within the Failure Records conditions.
4. Using the scan tool, monitor the Specific DTC Info for DTC P1352.

Does the scan tool indicate DTC 1352 failed this ignition?

--

Go to Step 2

System OK