Circuit Description
The Crankshaft Position (CKP) Sensor sensds an AC voltage signal to the Ignition Control Module (ICM).The Ignition Control Module (ICM) sends a reference signal to the Powertrain Control Module (PCM) seven times per crankshaft revolution to indicate crankshaft position and RPM so that the PCM can determine when to pulse the ignition coils and control the ignition timing. This signal is called medium resolution (7X reference) because it occurs seven times per crankshaft revolution. The ICM applies 5 volts through the 7X reference circuit and, in effect, switches this circuit to ground for a very short period of time. The seventh pulse is the sync pulse and is used for crankshaft position reference.
Conditions For Running The DTC
| • | No active ECT DTC's |
| • | No active TP DTC's |
| • | The engine running. |
Conditions for Setting the DTC
The CKP resync counter is more than 15 counts within 4 minutes and 15 seconds.
Action Taken When the DTC Sets
| • | The control module illuminates the malfunction indicator lamp (MIL) if a failure is detected during 2 consecutive key cycles. |
| • | The control module sets the DTC and records the operating conditions at the time the diagnostic failed. The failure information is stored in the scan tool Freeze Frame/Failure Records. |
Conditions for Clearing the MIL or DTC
| • | The control module turns OFF the MIL after 3 consecutive drive trips when the test has run and passed. |
| • | A history DTC will clear if no fault conditions have been detected for 40 warm-up cycles. A warm-up cycle occurs when the coolant temperature has risen 22°C (40°F) from the startup coolant temperature and the engine coolant reaches a temperature that is more than 70°C (158°F) during the same ignition cycle. |
| • | Use a scan tool in order to clear the DTCs. |
Diagnostic Aids
| • | Inspect the CKP sensor harness in order to ensure that it is not routed too close to any non-engine related electronic component or harness. |
| • | Inspect the wiring harness for damage. If the harness appears to be OK, observe the medium resolution resync counter on the scan tool while moving connectors and wiring harnesses related to the CKP sensor. If the medium resolution resync counter still does not count, then while still observing the scan tool operate any non-engine related electrical components on the vehicle. A change in display will indicate the location of the malfunction. |
| • | A rubbed through wire insulation or a poor connection may cause an intermittent problem. |
| • | A defective reluctor wheel or a cracked or damaged CKP sensor can result in an intermittent. Remove the crankshaft sensor and inspect for any damage. With the CKP sensor removed you can also inspect the reluctor wheel through the hole. Check the porosity and condition of the wheel. |
An intermittent may be caused by any of the following conditions:
| • | A poor connection |
| • | Rubbed through wire insulation |
| • | A broken wire inside the insulation |
Thoroughly check any circuitry that is suspected of causing the intermittent complaint. Refer to Intermittents and Poor Connections Diagnosis in Wiring Systems.
If a repair is necessary, refer to Wiring Repairs or Connector Repairs in Wiring Systems.
Test Description
The numbers below refer to the step numbers on the Diagnostic Table.
Step | Action | Value(s) | Yes | No | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | ||||||||||
2 | Attempt to start the engine. Will the engine start? | -- | ||||||||||
3 | Visually inspect the wiring harness of the CKP sensor including the CKP reference signal circuit from the ICM to the PCM for improper routing near high voltage circuits, all other circuitry or for contacting any metal surface and moving components. Did you find and correct any condition? | -- | ||||||||||
|
Caution: Avoid contact with moving parts and hot surfaces while working around a running engine in order to prevent physical injury. With the engine running, wiggle the harness connectors of the following components and related circuits, while listening for the engine to stumble:
Does the engine stumble? | -- | Go to Diagnostic Aids | ||||||||||
5 |
Did you find a problem? | -- | ||||||||||
6 |
Did you find a problem? | -- | ||||||||||
7 |
Did you find a problem? | -- | Go to Diagnostic Aids | |||||||||
8 |
Does the scan tool indicate that this diagnostic has ran and passed? | -- | ||||||||||
9 | Check to see if any additional DTCs are set. Does the scan tool display any DTCs that you have not diagnosed? | -- | Go to the applicable DTC table | System OK |
