DTC P0372 IC 24X Reference Circuit Missing Pulses. Oldsmobile Shelby Series 1 1999

For 1990-2009 cars
Engine Controls Components
Ignition Control Module
OBD II Symbol Description Notice
Powertrain Control Module Connector End Views
Handling ESD Sensitive Parts Notice
Handling ESD Sensitive Parts Notice

### Circuit Description

This diagnostic test checks for less than forty-eight pulses between CAM pulses. However, the number of 24X pulses is allowed to vary between 47 and 49, as long as any variances toggle between too few pulses, and too many pulses. If two variances do not toggle, i.e. they both had 47 reference pulses and eight 4X reference pulses were received between CAM events, then DTC P0372 is set because some 24X pulses were missed.

### Conditions for Running the DTC

• | At least one CAM pulse was received in the last 0.25 seconds.

• | Engine speed is between 496 and 1,200 RPM.

• | Number of CAM pulses since key ON is 7 or more.

• | Eight 4X reference pulses have been received between CAM pulses.

### Conditions for Setting the DTC

• | Less than 47 24X reference pulses seen between CAM pulses.

| OR

• | 47 24X reference pulses were received twice in a row.

### Action Taken When the DTC Sets

• | The PCM illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails.

• | The PCM records the operating conditions at the time the diagnostic fails. The PCM stores this information in the Freeze Frame and/or Failure Records.

### Conditions for Clearing the MIL/DTC

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

• | A last test failed, or current DTC, clears when the diagnostic runs and does not fail.

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

• | Use a scan tool in order to clear the MIL and the DTC.

### Test Description

The numbers below refer to the step numbers on the diagnostic table.

1. If DTC P1323 is set, diagnose it first.

2. Using the Freeze Frame and Failure Records can help locate an intermittent condition. Operate the vehicle within the same conditions that you observed in the Freeze Frame and Failure Records.

3. This step is testing for a poor connection or an intermittent open circuit which would set this DTC. Move all related ignition control and PCM harnesses in order to help isolate where the circuit condition is located.

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 | Is DTC P1323 also set? | -- | Go to DTC P1323 IC 24X Reference Circuit Low Frequency | Go to Step 3

3

1. Turn ON the ignition, with the engine OFF.
2. Review the Freeze Frame and/or Failure Records data for this DTC and observe the parameters.
3. Turn OFF the ignition for 15 seconds.
4. Start the engine.
5. Operate the vehicle within the conditions required for this diagnostic to run, and as close to the conditions recorded in Freeze Frame and Failure Records as possible. Special operating conditions that you need to meet before the PCM will run this diagnostic, where applicable, are listed in Conditions for Running the DTC.
6. Monitor the diagnostic trouble code (DTC) information with a scan tool.

Does the scan tool indicate that this diagnostic failed this ignition?

--

Go to Step 4

Go to Diagnostic Aids

4

1. Start and idle the engine.
2. Monitor the engine RPM with a scan tool while moving related harnesses and connectors.

Does the engine RPM displayed on the scan tool change abruptly with harness and connector movement?

--

Go to Step 5

Go to Step 6

5

1. Test for poor connections and intermittent opens in the 24X signal circuit. Refer to Intermittents and Poor Connections Diagnosis in Wiring Systems.
2. If you find a poor connection or open circuit repair as necessary. Refer to Wiring Repairs and Repairing Connector Terminals in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 7

Go to Step 6

6 | Repair the intermittent short to ground in the ignition control 24X signal circuit. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | Go to Step 7 | --

7

1. Select the Diagnostic Trouble Code (DTC) option and the Clear DTC option with the scan tool.
2. Idle the engine at the normal operating temperature.
3. Select the Diagnostic Trouble Code (DTC) option and the specific DTC option, then enter the DTC number with the scan tool.
4. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text, if applicable.

Does the scan tool indicate that this test ran and passed?

4.2 V

Go to Step 8

Go to Step 2

8 | Select the Capture Info option and the Review Info option with the scan tool. Does the scan tool display any DTCs that you have not diagnosed? | -- | Go to the applicable DTC table | System OK