2002 Deville

[LINDAL]

Car started back up again. I checked for codes and it had the PCM PO385 current code.

DTC P0385

Crankshaft Position (CKP) Sensor B Circuit

Can someone tell me what the code means?

Turned the motor off at the grocery store. Checked the codes again and it was gone. I must be resetting them some how. I just turn the ignition off when it asks if I want to reset.

After posting I see that the other 2002 I had was showing a po340 code and the crankshaft sensor is not too bad to change. Is this correct?

[Bruce Nunnally]

DTC P0385

Circuit Description

The powertrain control module (PCM) uses dual crankshaft position (CKP A and CKP sensors in order to determine crankshaft position. The PCM supplies an ignition voltage and a ground for each sensor. During engine rotation, a slotted ring, machined into the crankshaft, causes the sensors to return a series of ON and OFF pulses to the PCM. The PCM uses these pulses to decode the position of the engine crankshaft.

The PCM uses two basic methods of decoding the engine position: Angle Based and Time Based (using either CKP A or CKP B sensor input). During normal operation, the PCM uses the angle based method. In order to operate in this mode, the PCM must receive signal pulses from both CKP sensors. The PCM uses the signal pulses to determine an initial crankshaft position, and to generate MEDRES (24X reference) and LORES (4X reference) signals. Once the initial crank position is determined, the PCM continuously monitors both sensors for valid signal inputs. As long as both signal inputs remain, the PCM will continue to use the angle based mode.

When either CKP signal is lost, the PCM will compare the MEDRES signal to the camshaft position (CMP) sensor signal. If the PCM detects a valid CMP signal, and the MEDRES to CMP signal correlation is correct, the PCM determines that CKP sensor A is at fault. However, if the MEDRES to CMP correlation is incorrect, the PCM determines that CKP sensor B is at fault. If the PCM determines that CKP sensor B is at fault, DTC P0385 will set. The PCM will switch from angle based mode to Time Based Mode A using CKP sensor A signal input.

Conditions for Running the DTC

The engine is cranking or running.

Conditions for Setting the DTC

The PCM detects a loss of CKP sensor B signal.

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.

The diagnostic steps through how to determine if the problem is the sensor, or the wiring going to the sensor, or the connector for the sensor.

We do know however that these sensors do fail. Sounds like something that even I could replace:

Camshaft Position (CMP) Sensor Replacement

Removal Procedure

Remove the camshaft sensor electrical connector.

Remove the camshaft retaining bolt.

Remove the camshaft sensor.

Installation Procedure

Important

Inspect the camshaft sensor o-ring for wear or damage. If a problem is found, replace the o-ring.

Lubricate the camshaft o-ring with engine oil.

Notice

Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.

Install the camshaft sensor and retaining bolt. Tighten

Tighten the retaining bolt between 10 N·m (89 lb in).

Reconnect the camshaft sensor electrical connector.

Operate the engine and inspect the camshaft sensor for engine oil leaks.

[LINDAL]

Thanks!

[Ranger]

Linda,

GM had a bad supplier of CKP sensors from 2000 - early '03. Nearly every one will have to be changed. They are located above the oil filter adapter, which will need to be removed first. Change both sensors while your there. The symptoms are engine stalls. It may happen at idle or while driving on the highway. The engine will always restart with no trouble.

[LINDAL]

Thanks!

[Poobah]

I had the same problem with my 2000. I bought the sensors and had my mechanic switch them out. I'm told they are hard to reach unless you have skinny hands and get the car up on a hoist.

Cadillac has redesigned the crankshaft sensors twice since 2000 - 2003. The current ones are supposed to be quite reliable.