Circuit Description
The crankshaft position (CKP) sensor contains 2 hall-effect switches in one housing. This sensor configuration produces 2 separate CKP sensor pulses. These pulses occur when 2 interrupter rings, mounted to the crankshaft balancer, the outer one containing 18 evenly spaced windows and blades, the inner one containing 3 unevenly spaced windows and blades, pass by the sensors. The 18X sensor produces 18 pulses per engine revolution. The 3X sync sensor produces 3 pulses per engine revolution, each pulse representing a pair of companion cylinders. Both sensors are connected directly to the ignition control module (ICM). The sensor wiring includes the following circuits:
| • | The CKP sensor 1 signal circuit |
| • | The CKP sensor 2 signal circuit |
| • | A shared 12-volt reference circuit |
| • | A shared low reference circuit |
The ICM uses the sensors to determine the engine position and speed. A signal converter within the ICM, using the CKP sensor 1 18X pulse, produces a digital 3X output signal 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 does not receive a 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 a fault in the low resolution engine speed signal circuit 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: Powertrain Control Module Connector End Views or Engine Controls 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 indicate that the 18X Crank Sensor parameter is more than 2,000 RPM? | Go to Step 4 | Go to Step 3 |
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 parameter 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 |
