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For 1990-2009 cars only
Makes 🢒 Oldsmobile 🢒 1999 🢒 Aurora 🢒 DTC 🢒 DTC P1323 IC 24X Reference Circuit Low Frequency

Object Number: 191605 Size: SF
Cell 21: IAT, ECT, TP, MAP Sensors
Engine Controls Components
OBD II Symbol Description Notice
ESD Notice

Circuit Description

The Ignition Control Module creates a 4X signal and a 24X signal that is used by the 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
    •  DTCs P0340 and P1376 are 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.
    •  Engine speed greater 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 (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

Number(s) below refer to the step number(s) on the Diagnostic Table.

  1. Check to see if DTC P1376 is set because a REF LO problem can cause other ignition problems.

    2.

  2. IC module output should be 4.2 volts or more.

    3.

  3. IC module frequency output should be 30 Hz or more.

    A diagnostic jumper can be created with the terminals supplied in the J 38125-A Terminal Repair Kit. Assemble the jumpers and terminals and cover the exposed terminals with heat shrink tubing. Do not cover the spade of the male terminals.

Step

Action

Value(s)

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 P1376 also set?

--

Go to DTC P1376 Ignition Ground Circuit

Go to Step 3

3
  1. Record fluid life indexes, turn the key to LOCK and wait 30 seconds.
  2. Disconnect IC module connector C4.
  3. Disconnect PCM connector C2.
  4. Using DMM J 39200 measure the resistance to ground at PCM connector C2 terminal 5.

Is the resistance more than the value specified?

10K ohms

Go to Step 4

Go to Step 8

4

Measure the resistance between IC module connector C4 terminal A and PCM connector C2 terminal 5.

Is the resistance the same or less than the value specified?

5 ohms

Go to Step 5

Go to Step 9

5

  1. Reconnect IC module connector C4.
  2. Turn the key ON.
  3. Measure the voltage to ground at PCM connector C2 terminal 5.

Is the voltage more than the value specified?

4.2 volts

Go to Step 6

Go to Step 10

6

  1. Turn the key to LOCK.
  2. Reconnect PCM connector C2.
  3. Disconnect IC module connector C4.
  4. Install diagnostic jumper.

    5. OR:

    • Jumper C4 terminal A to module pin A.
    • Jumper C4 terminal B to module pin B.
    • Jumper C4 terminal C to module pin C.
    • Jumper C4 terminal D to module pin D.
    • Jumper C4 terminal E to module pin E.
    • Jumper C4 terminal F to module pin F.
  5. Set the DMM to 400 mV A/C scale and push the Hz button.
  6. Start the engine.
  7. Connect the DMM between jumper A and ground.

Does the FREQUENCY measure less than the value specified?

200 Hertz

Go to Step 10

Go to Step 7

7
  1. Remove all jumpers.
  2. Reconnect IC module connector C4.
  3. Clear the DTC.
  4. Start and idle engine.
  5. Using a scan tool select DTC Information.

Has DTC P1323 Failed This Ign.?

--

Go to Step 13

Fault not present. Refer to Diagnostic Aids

8

Repair the short to ground in the 24X Spark Reference circuit.

Is the repair complete?

--

Go to Powertrain Control Module Diagnosis for Verify Repair

--

9

Repair the open in the 24X Spark Reference circuit.

Is the repair complete?

--

Go to Powertrain Control Module Diagnosis for Verify Repair

--

10
  1. Check terminal contact at the IC module.
  2. Repair terminal contact if needed.

Was terminal contact repaired?

--

Go to Powertrain Control Module Diagnosis for Verify Repair

Go to Step 12

12

Replace the Ignition Control Module. Refer to Ignition Control Module Replacement .

Is the replacement complete?

--

Go to Powertrain Control Module Diagnosis for Verify Repair

--

13
  1. Check terminal contact at the PCM connector C2 terminal 5.
  2. Repair terminal contact if needed.

Was terminal contact repaired?

--

Go to Powertrain Control Module Diagnosis for Verify Repair

Go to Step 14

14

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

Is the replacement complete?

--

Go to Powertrain Control Module Diagnosis for Verify Repair

--