P023

Diagnostic Trouble Code Chart P023 (Part 1 Of 2):

Diagnostic Trouble Code Chart P023 (Part 2 Of 2):

Ignition Control Module Circuit:

CIRCUIT DESCRIPTION
For complete description of how ignition spark is controlled by the Powertrain Control Module (PCM) and Ignition Control Module (ICM), refer to Ignition System/Description and Operation. Description and Operation

FAILURE CONDITION
Code P023 will set under either of the two following conditions:

1. 4X reference pulses are being received by the PCM and the bypass line is low, and the PCM detects pulses on the ignition control line. This could be caused by the bypass line shorted to voltage, or a faulty ignition control module.
2. 4X reference pulses are being received by the PCM and the bypass line is high, and the PCM does NOT detect a signal on the ignition control line. This could be caused by an open or a shorted to ground ignition control line or bypass line open or shorted to ground.

TEST CONDITION # 1 CRANK
1. Code P035 is not set.
2. Bypass line low (0 volt).
3. At least two 4X reference pulses have been received by the PCM;
OR
Test # 2 failed previously this ignition cycle.

TEST CONDITION # 2 RUN
1. Code P035 is not set.
2. Bypass line High (5 volts).
3. At least two 4X reference pulses have been received by the PCM.

FAILURE CONDITION # 1 CRANK
Ignition control pulses detected on CKT 423 in bypass;
OR
Test # 2 failed previously this ignition cycle.

FAILURE CONDITION # 2 RUN
No ignition control pulses detected on CKT 423.

ACTION TAKEN
1. PCM turns "ON" Malfunction Indicator Lamp (Service Engine Soon) (MIL).
2. PCM-controlled spark is disabled for ignition cycle.
3. PCM disables Exhaust Gas Recirculation (EGR).
4. Transaxle shift adapts are maintained at current levels.

NOTES ON FAULT TREE
(Part 1 of 2)
1. Check if Code P035 is set because a REF LO problem can cause other ignition problems.
2. Checking to see if Code P023 was set during "CRANK" or while engine was running.
3. Checking if there is a short to voltage on CKT 424 or if a PCM failure is causing the ignition control system to be in bypass spark control when it should not be.
4. Checking to see if there is an open in CKT 423 that is causing no ignition control pulses to reach the ignition control module or if pulses are reaching the ignition control module and it is doing nothing with them.
5. Checking for a short to voltage on CKT 424.

(Part 2 of 2)
6. Checking if bypass control is being sent by the PCM to the ignition control module. If bypass control is being sent the voltage will be greater than 4.1 volts.
7. Checking if bypass control being sent by the PCM is being received by the ignition control module. If CKT 424 is good, resistance will be less than 5.
8. Checking if PCM is providing proper signal to the ICM. If PCM terminal "3F3" has between 30 and 100 Hertz, the PCM is not at fault.
9. Checking if PCM can produce the proper ignition control pulses. If max voltage exceeds 3.7 volts, the PCM is OK and the ICM is at fault.
10. Checking CKT 424 for a short to ground.
11. Checking if the ICM is able to recognize a Bypass Signal. If it does, Code P023 will not set again. If Code P023 resets the ICM is faulty, if it does not reset the PCM is faulty.
12. Checking if ICM is causing incorrect voltage or if PCM is supplying incorrect signal.