Refer to
Cell 21: Ignition Controls
.
Circuit Description
During cranking, the Ignition Control Module (ICM) monitors the 7X crankshaft position sensor signal. Once the ICM determines spark synchronization, 3X reference signals are sent to the PCM. The PCM will command all six injectors ON for one priming shot of fuel in all cylinders. After the priming, the injectors are left OFF for the next six fuel control reference signals (two crankshaft revolutions). This allow each cylinder a chance to use the fuel from the priming shot. During this waiting period, a cam pulse will have been received by the PCM. The PCM uses the Cam signal pulses to initiate sequential fuel injection. The PCM constantly monitors the number of pulses on the Cam signal circuit and compares the number of Cam pulses to the number of 24X reference pulses and the number of 3 X reference pulses being received. If the PCM receives an incorrect number of pulses on the Cam reference circuit, DTC P034 will set and the PCM will initiate injector sequence without the Cam signal with a one in six chance that injector sequence is correct. The engine will continue to start and run normally, although the misfire diagnostic will be affected if a misfiring condition occurs.
Conditions for Running the DTC
The engine is running (3X reference pulses are being received).
Conditions for Setting the DTC
CMP sensor reference pulse is not detected every engine cycle.
Action Taken When the DTC Sets
| • | The PCM will illuminate the malfunction indicator lamp (MIL) during the second consecuitive trip in which the diagnostic has been run and failed. |
| • | If equipped with traction control, the PCM will command the EBTCM via the serial data circuit to turn OFF traction control, and the EBTCM will illuminate the TRACTION OFF lamp. |
| • | The PCM will store conditions which were present when the DTC set as Freeze Frame and Failure Records data. |
Conditions for Clearing the MIL/DTC
| • | The PCM will turn OFF the MIL during the third consecutive trip in which the diagnostic has been 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 the scan tool. |
Diagnostic Aids
DTC P0341 can be caused by secondary components leaking high voltage into the ignition module. Check for the following conditions:
| • | Incorrect harness routing near secondary ignition component. |
| • | Ignition coil arcing to wiring harness or Ignition Control Module (check ignition coils for cracks, carbon tracking, or other signs of damage). |
| • | Secondary ignition wire(s) arcing to wiring harness. |
An intermittent may be caused by a poor connection, rubbed through wire insulation or a wire broken inside the insulation. Check for:
| • | Faulty Ignition Coil. Inspect the ignition coils for cracks, carbon tracking, or other signs that indicate that the coil secondary circuit is arcing to the IC Module or IC Module wiring harness. |
| • | Poor connection. Inspect the PCM harness and connectors for improper mating, broken locks, improperly formed or damaged terminals, and poor terminal to wire connection. |
| • | Damaged harness. Inspect the wiring harness for damage. If the harness appears to be OK, disconnect the PCM, turn the ignition on and observe a voltmeter connected to the CAM signal circuit at the PCM harness connector while moving connectors and wiring harnesses related to the 24X CKP Sensor and CMP Sensor. The CMP and 24X CKP sensors share the same sensor feed from the PCM. A change in voltage will indicate the location of the fault. |
| • | It may also be helpful to monitor the CAM SIGNAL PRESENT on the scan tool. |
Refer to Intermittents and Poor Connections Diagnosis Connector Repairs and Wiring Repairs in Wiring Systems.
Reviewing the Fail 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.
Test Description
Number(s) below refer to the step number(s) on the Diagnostic Table:
-
The Cam Signal on the scan tool should change each time the signal circuit is touched.
-
If the fuse blows in the jumper wire, there is a short to ground on the signal circuit.
-
This vehicle is equipped with a PCM which utilizes an Electrically Erasable Programmable Read only Memory (EEPROM). When the PCM is being replaced, the new PCM must be programmed.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Was the Powertrain on Board Diagnostic (OBD) System Check performed? | -- | ||
2 |
Does scan tool indicate DTC P0341 failed this ignition? | -- | Go To Diagnostic Aids | |
3 | Using the scan tool monitor Cam Signal. Is Cam Signal Present? | -- | Go To Diagnostic Aids | |
4 |
Does J 39200 DMM display a voltage near the specified value? | B+ | ||
5 |
Was a problem found? | -- | ||
6 |
Does J 35616-200 test lamp light? | -- | ||
7 |
Was a problem found? | -- | ||
Does Cam Signal change EACH time the signal circuit is touched? | -- | |||
Did the fuse in the jumper wire blow? | -- | |||
10 | Check signal circuit for an open or a short to voltage, if a problem is found repair as necessary. Refer to Wiring Repairs . Was a problem found? | -- | ||
11 | Check signal circuit for a short to ground, if a problem is found repair as necessary. Refer to Wiring Repairs in Wiring Systems. Was a problem found? | -- | ||
12 | Check connections at PCM and replace terminals as necessary. Refer to Intermittents and Poor Connections Diagnosis Repairing Connector Terminals and Connector Repairs in Wiring Systems. Did any terminals require replacement? | -- | ||
13 |
Important: : Replacement PCM must be reprogrammed. Refer to Powertrain Control Module Replacement/Programming . Replace the PCM. Is the action complete? | -- | -- | |
14 | Check connections at CMP sensor and replace terminals as necessary. Refer to Intermittents and Poor Connections Diagnosis Repairing Connector Terminals and Connector Repairs in Wiring Systems. Did any terminals require replacement? | -- | ||
15 | Replace CMP sensor. Refer to Camshaft Position (CMP) Sensor Replacement . Is the action complete? | -- | -- | |
Does scan tool indicate DTC P0341 failed this ignition? | -- | System OK |
