Circuit Description
The 18X reference signal is produced by the ignition control module. The ICM calculates the 18X reference signal by filtering the crankshaft position (CKP) sensor 18X pulses when the engine is running and CKP sync pulses are also being received. The PCM uses the 18X reference signal to calculate engine RPM and crankshaft position at engine speeds less than 1200 RPM. The PCM constantly monitors the number of pulses on the 18X reference circuit and compares the number of 18X reference pulses to the number of 3 X reference pulses and CAM signal pulses being received. If the PCM receives an incorrect number of pulses on the 18X reference circuit, DTC P0336 will set and the PCM will use the 3X reference signal circuit for fuel and ignition control. The engine will continue to start and run using the 3X reference and CAM signals only.
Conditions for Running the DTC
The engine is running (3X reference pulses are being received).
Conditions for Setting the DTC
No 18X reference pulses are not received in one engine cycle (720 degrees of crankshaft rotation).
Action Taken When the DTC Sets
| • | The PCM illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails. |
| • | The PCM records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the PCM stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the PCM records the operating conditions at the time of the failure. |
| • | The PCM writes the conditions to the Freeze Frame and updates the Failure Records. |
Conditions for Clearing the MIL/DTC
| • | The PCM will turn OFF the malfunction indicator lamp (MIL) during the third consecutive trip in which the diagnostic has 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 a scan tool. |
Diagnostic Aids
Inspect for the following:
| • | Incorrect harness routing near secondary ignition components. |
| • | Faulty Ignition Coil - Remove the ignition coils and inspect the ignition control module and coils for cracks, carbon tracking, or other signs that indicate that the coil secondary circuit is arcing to the ICM or ICM wiring harness. Refer to Ignition Coil Replacement . |
| • | Secondary ignition wires arcing to wiring harness - Inspect secondary ignition wires for carbon tracking or other signs of damage. |
Many situations may lead to an intermittent condition. Perform each inspection or test as directed.
Important: : Remove any debris from the connector surfaces before servicing a component. Inspect the connector gaskets when diagnosing or replacing a component. Ensure that the gaskets are installed correctly. The gaskets prevent contaminate intrusion.
| • | Loose terminal connection |
| - | Use a corresponding mating terminal to test for proper tension. Refer to Testing for Intermittent Conditions and Poor Connections , and to Connector Repairs in Wiring Systems for diagnosis and repair. |
| - | Inspect the harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and faulty terminal to wire connection. Refer to Testing for Intermittent Conditions and Poor Connections , and to Connector Repairs in Wiring Systems for diagnosis and repair. |
| • | Damaged harness--Inspect the wiring harness for damage. If the harness inspection does not reveal a problem, observe the display on the scan tool while moving connectors and wiring harnesses related to the sensor. A change in the scan tool display may indicate the location of the fault. Refer to Wiring Repairs in Wiring Systems for diagnosis and repair. |
| • | Inspect the powertrain control module (PCM) and the engine grounds for clean and secure connections. Refer to Wiring Repairs in Wiring Systems for diagnosis and repair. |
If the condition is determined to be intermittent, reviewing the Snapshot or Freeze Frame/Failure Records may be useful in determining when the DTC or condition was identified.
Step | Action | Values | Yes | No | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics Connector End View Reference: Engine Controls Connector End Views or Powertrain Control Module Connector End Views | ||||||||||||
1 | Did you perform the Powertrain On-Board (OBD) system check? | -- | Go to Step 2 | |||||||||
2 | Attempt to start the engine. Does the engine start and run? | -- | Go to Step 3 | Go to Step 8 | ||||||||
3 | Observe the 18X Crank Sensor parameter with the scan tool. Does the 18X Crank Sensor parameter change with engine speed? | -- | Go to Step 4 | Go to Step 5 | ||||||||
4 |
Does the DTC fail this ignition? | -- | Go to Step 5 | Go to Testing for Intermittent Conditions and Poor Connections | ||||||||
5 |
Does the test lamp illuminate? | -- | Go to Step 10 | Go to Step 6 | ||||||||
6 |
Does the test lamp illuminate? | -- | Go to Step 9 | Go to Step 7 | ||||||||
7 |
Does the 18X Crank Sensor change? | -- | Go to Step 13 | Go to Step 11 | ||||||||
8 |
Is the voltage within the specified range? | 4-8 V | Go to Step 14 | Go to Step 12 | ||||||||
9 | Test the 18X reference medium resolution engine speed signal circuit between the ICM and the powertrain control module (PCM) for a short to ground. Refer to Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 20 | Go to Step 19 | ||||||||
10 | Test the 18X reference medium resolution engine speed signal circuit between the ICM and the PCM for a short to voltage. Refer to Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 20 | Go to Step 19 | ||||||||
11 | Test the 18X reference medium resolution engine speed signal circuit between the ICM and the PCM for an open. Refer to Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 20 | Go to Step 16 | ||||||||
12 | Test the CKP sync signal circuit for an open. Refer to Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 20 | Go to Step 15 | ||||||||
13 | Inspect for the following conditions:
Did you find and correct the condition? | -- | Go to Step 20 | Go to Step 15 | ||||||||
14 | Test for an intermittent or for poor connections at the CKP sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | -- | Go to Step 20 | Go to Step 17 | ||||||||
15 | Test for an intermittent or for poor connections at the ICM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | -- | Go to Step 20 | Go to Step 18 | ||||||||
16 | Test for poor connections at the PCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | -- | Go to Step 20 | Go to Step 19 | ||||||||
17 | Replace the CKP sensor. Refer to Crankshaft Position Sensor Replacement . Did you complete the replacement? | -- | Go to Step 20 | -- | ||||||||
18 | Replace the ICM. Refer to Ignition Control Module Replacement . Did you complete the replacement? | -- | Go to Step 20 | -- | ||||||||
19 | Replace the PCM. Refer to Powertrain Control Module Replacement/Programming for replacement, setup, and programming. Did you complete the replacement? | -- | Go to Step 20 | -- | ||||||||
20 |
Did the DTC fail this ignition? | -- | Go to Step 2 | Go to Step 21 | ||||||||
21 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | -- | System OK | |||||||||
