Circuit Description
The PCM supplies B+ and a ground to the crankshaft position (CKP) sensor. The CKP sensor sends a reference signal to the PCM seven times per revolution in order to indicate the CKP position and the engine speed. This signal is called the 7X reference signal because the signal occurs seven times per revolution. The seventh pulse is the sync pulse. The PCM uses this seventh pulse for the crankshaft position reference. The PCM can calculate when to pulse the ignition coils based on this information.
Conditions For Setting The DTC
The 7X resync counter goes greater than 15 within 4 minutes and 15 seconds.
Action Taken When the DTC Sets
| • | The malfunction indicator lamp (MIL) will illuminate. |
| • | The PCM will record the operating conditions at the time that the diagnostic fails. The Freeze Frame and Failure Records buffers will store this information. |
| • | A history DTC stores. |
Conditions for Clearing the MIL/DTC
| • | The malfunction indicator lamp (MIL) will turn OFF after 3 consecutive ignition cycles in which the diagnostic runs without a fault. |
| • | A history DTC will clear after 40 consecutive warm up cycles without a fault. |
| • | Use a scan tool to clear the DTCs. |
Diagnostic Aids
| • | If the complaint was Cranks But Will Not Run, the DTC P0335 may set when attempting to start the engine more than 15 times and the ignition is not turned OFF between the attempts. |
| • | A rubbed through wire insulation or a poor connection may cause an intermittent problem. |
| • | A defective reluctor wheel can result in an intermittent. Remove the crankshaft sensor and inspect the reflector wheel through the hole. Check the porosity and condition of the wheel. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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The Powertrain OBD System Check prompts the technician to complete some basic checks and store Freeze Frame Data and Failure Records on the scan tool if applicable. This creates an electronic copy of the data taken when the fault occurs. Refer to this information on the scan tool later.
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When a med. resync occurs, engine stumble also occurs. Whenever a component connection or wire is at fault, wiggling the circuit or connector will induce an engine stumble.
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Operating a faulty non-engine related electronic components may emit electromagnetic interferences which may cause a med. resync.
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Before replacing the PCM, check the terminals for improper mating, broken locks, or physical damage to the wiring harness. Reprogram the replacement PCM. Refer to the latest Techline information for programming procedures.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | |||
2 | Attempt to start the engine. Does the engine start and continue to run. | -- | ||
3 |
Did the MIL illuminate? | 5 | ||
|
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 connectors of the PCM and the CKP sensor and related circuits while listening for an engine stumble. Does the engine stumble? | -- | |||
Operate any non-engine related electronic components on the vehicle. Does the Med. Resolution Resync Counter on the scan tool resync while operating any non-engine related electronic components? | -- | |||
6 |
Is the action complete? | -- | -- | |
7 | Did the MIL illuminate in Step 3? | -- | ||
8 | Check the wiring to the PCM and the CKP sensor for rubbed through wire insulation or for being pinched and repair as necessary. Refer to Wiring Repairs in Engine Electrical. Was a repair necessary? | -- | ||
9 | Repair the circuitry or faulty or interfering component. Refer to Wiring Repairs in Engine Electrical. Is the action complete? | -- | -- | |
10 |
Did the MIL illuminate? | 5 | ||
Replace the PCM. Refer to Powertrain Control Module Replacement/Programming . Is the action complete? | -- | -- | ||
12 |
Does the scan tool indicate that this diagnostic ran and passed? | 90°-95° C | ||
13 | Check if any additional DTCs are set. Are any DTCs displayed that have not been diagnosed? | -- | Go to the Applicable DTC Table | System OK |
