Circuit Description
The crankshaft position (CKP) sensor B is a 7X variable reluctance sensor. This produces 7 digital ON/OFF pulses per engine revolution. These pulses occur when a reluctor wheel, mounted to the crankshaft and containing 6 slots evenly spaced 60 degrees apart and 1 slot spaced at 10 degrees, passes by the sensor. The 7X sensor is connected directly to the ignition control module (ICM). The sensor wiring includes 2 circuits, a CKP sensor signal circuit and a low reference circuit. The ICM uses the 7X signal to determine the engine position and speed. A signal converter within the ICM produces a digital 3X output pulse to the powertrain control module (PCM) on the low resolution engine speed signal circuit. The PCM monitors the low resolution engine speed signal circuit for errors. If the PCM receives no signal from the ICM, DTC P0385 sets.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P0385 Crankshaft Position (CKP) Sensor B Circuit
Conditions for Running the DTC
| • | The engine run time is more than 3 seconds. |
| • | DTC P0385 runs continuously when the above condition is met. |
Conditions for Setting the DTC
| • | The PCM detects the following for every 2 engine revolutions: |
| - | Forty eight medium resolution engine speed signals |
| - | One CMP sensor signal |
| - | Zero low resolution engine speed signals |
| • | The condition exists for more than 8 seconds. |
Action Taken When the DTC Sets
| • | The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails. |
| • | The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records. |
Conditions for Clearing the MIL/DTC
| • | The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail. |
| • | A current DTC, Last Test Failed, clears when the diagnostic runs and passes. |
| • | A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic. |
| • | Clear the MIL and the DTC with a scan tool. |
Step | Action | 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 Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information |
2 |
Does the scan tool display 3X Crank Sensor RPM? | Go to Step 3 | Go to Step 4 |
3 |
Did the DTC fail this ignition? | Go to Step 4 | Go to Intermittent Conditions |
4 |
Does the test lamp illuminate? | Go to Step 8 | Go to Step 5 |
5 |
Does the test lamp illuminate? | Go to Step 7 | Go to Step 6 |
6 |
Does the 3X Crank Sensor RPM change? | Go to Step 10 | Go to Step 9 |
7 | Test the low resolution engine speed signal circuit between the ICM and the powertrain control module (PCM) for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 14 | Go to Step 13 |
8 | Test the low resolution engine speed signal circuit between the ICM and the PCM for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 14 | Go to Step 13 |
9 | Test the low resolution engine speed signal circuit between the ICM and the PCM for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 14 | Go to Step 11 |
10 | Test for an intermittent and poor connection at the ICM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 14 | Go to Step 12 |
11 | Test for an intermittent and poor connection at the PCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 14 | Go to Step 13 |
12 | Replace the ICM. Refer to Ignition Control Module Replacement . Did you complete the replacement? | Go to Step 14 | -- |
13 | Replace the PCM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming. Did you complete the replacement? | Go to Step 14 | -- |
14 |
Did the DTC fail this ignition? | Go to Step 2 | Go to Step 15 |
15 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | Go to Diagnostic Trouble Code (DTC) List - Vehicle in Vehicle DTC Information | System OK |
