DTC P1323 IC 24X Reference Circuit Low Frequency. Oldsmobile Shelby Series 1 1999

For 1990-2009 cars only

Makes 🢒 Oldsmobile 🢒 1999 🢒 Shelby Series 1 🢒 Engine 🢒 Engine Controls - 4.0L 🢒 DTC P1323 IC 24X Reference Circuit Low Frequency

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

The ignition control module (ICM) creates a 4X signal and a 24X signal that is used by the powertrain control module (PCM) for ignition and fuel control. In this diagnostic test, the PCM checks for 4X reference pulses being received without 24X reference pulses. When the engine is running and the PCM is receiving 4X reference pulses without 24X reference pulses and the 24X reference signal line is low for 4 seconds, DTC P1323 is set.

Conditions for Running the DTC

•	DTC P0340 is not set.

•	At least 7 CAM edges have been received this engine run cycle.

•	At least one CAM reference pulse was received within the last 4 seconds.

•	The engine speed is more than 496 RPM.

Conditions for Setting the DTC

No 24X reference pulses received by the PCM and the line is low for 4 seconds.

Action Taken When the DTC Sets

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

•	The PCM will record operating conditions at the time the diagnostic fails. This information will be stored in the Freeze Frame and Failure Records.

Conditions for Clearing the MIL/DTC

•	The PCM will turn the MIL OFF after three consecutive drive trips that the diagnostic runs and does not fail.

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

•	A History DTC will clear after forty consecutive warm-up cycles with no failures of any emission related diagnostic test.

•	Use a scan tool to clear DTCs.

•	Interrupting PCM battery voltage may or may not clear DTCs. This practice is not recommended. Refer to Clearing Diagnostic Trouble Codes in Powertrain Control Module Description .

Test Description

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

Using Freeze Frame and Failure Records may assist in locating an intermittent condition. Operate the vehicle within the same conditions that you observed in the Freeze Frame and Failure Records.

This step tests the camshaft position (CMP) sensor and wiring. If the DMM displays a frequency, then the CMP sensor and wiring are OK.

This step tests the output of the ignition control module (ICM). If the DMM displays a frequency, then the ignition module is OK.

DTC P0340

Step

Action

Values

Yes

Did you perform the Powertrain On-Board Diagnostic (OBD) System Check?

Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check

Turn ON the ignition, with the engine OFF.
Review the Freeze Frame and/or Failure Records data for this DTC and observe the parameters.
Clear the DTC.
Turn OFF the ignition for 15 seconds.
Attempt to start and idle the engine.
Using a scan tool, monitor the DTC information.

Is the CMP transitioning?

Did DTC P1323 set?

Go to Step 3

Go to Diagnostic Aids

Turn OFF the ignition.
Disconnect ICM connector C3.
Connect the DMM between the CMP reference signal circuits, at the ICM connector C3.
Measure the frequency from the CMP signal circuits.
Monitor the DMM while cranking the engine.

Does the DMM display a frequency while cranking the engine?

Go to Step 4

Go to Step 7

Inspect for poor connections at the ICM for the CMP sensor signal circuits. Refer to Intermittents and Poor Connections Diagnosis in Wiring Systems.
If you find a poor connection, repair the condition as necessary. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 11

Go to Step 5

Connect the ICM connector C3.
Disconnect the ICM connector C4.
Connect the DMM between the CMP signal terminal at the ICM and battery ground.
Measure the frequency from the ICM while cranking the engine.

Does the DMM display a frequency?

Go to Step 6

Go to Step 9

Disconnect the PCM connector C1.
Test the CMP signal circuit and the 24X spark reference circuit for the following:

•	An open circuit

•	A short to ground

•	A short to voltage

•	Poor connections

If you find a condition, repair as necessary. Refer to Wiring Repairs or Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 11

Go to Step 10

Disconnect the CMP sensor electrical connector.
Test the CMP signal circuits for the following:

•	An open circuit

•	A short to ground

•	A short to voltage

•	Poor connections

If you find a condition, repair as necessary. Refer to Wiring Repairs or Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 11

Go to Step 8

Replace the CMP sensor. Refer to Camshaft Position Sensor Replacement .

Is the action complete?

Go to Step 11

Replace the ICM. Refer to Ignition Control Module Replacement .

Is the action complete?

Go to Step 11

Important: The replacement PCM must be programmed.

Replace the PCM. Refer to Powertrain Control Module Replacement/Programming .

Is the action complete?

Go to Step 11

Select the Diagnostic Trouble Code (DTC) option and the Clear DTC option with the scan tool.
Idle the engine at the normal operating temperature.
Select the Diagnostic Trouble Code (DTC) option and the specific DTC option, then enter the DTC number with the scan tool.
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?

Go to Step 12

Go to Step 2

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