DTC P0385 Without RPO CTF
Circuit Description
The injection pump cam (CMP) sensor, also known as the auxiliary engine RPM sensor, is located in the fuel injection pump assembly, and is used to provide injection pump timing information to the engine control module (ECM). This sensor also acts as a backup system if the primary crankshaft position (CKP) sensor fails.
Conditions for Running the DTC
A crankshaft position (CKP) signal is detected for 1 second.
Conditions for Setting the DTC
No auxiliary engine RPM sensor signal is detected.
Action Taken When the DTC Sets
The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails.
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. |
| • | Clear the MIL and the DTC with a scan tool. |
Diagnostic Aids
Inspect for the following conditions:
| • | Poor connections at the ECM |
| Inspect the harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals, and poor terminal-to-wire connection. |
| • | Damaged harness |
| Inspect the wiring harness for damage, shorts to ground, shorts to battery, and open circuits. If the harness appears to be OK, observe the crank signal present display on the scan tool while moving connectors and wiring harnesses related to the CMP sensor. A change in the scan tool display will indicate the location of the fault. |
| • | White smoke |
| • | Inaccurate tachometer operation |
| CKP failure until the engine is turned OFF. |
| • | Unstable idle |
Step | Action | Value | Yes | No |
|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics | ||||
1 | Does the DTC set within 20 seconds after the engine is started and ran at 700 RPM or less? | -- | Go to Step 2 | Go to Intermittent Conditions |
2 |
Does the resistance measure within the specified range? | 1850-2450 ohms | Go to Step 6 | Go to Step 3 |
3 |
Does the resistance for each circuit measure less than the specified value? | 2 ohms | Go to Step 4 | Go to Step 8 |
4 | Measure the resistance between the auxiliary engine RPM sensor terminals. Does the resistance measure within the specified range? | 1850-2450 ohms | Go to Step 5 | Go to Step 9 |
5 | Measure the resistance between the auxiliary engine RPM sensor terminal, positive and negative, and the auxiliary engine RPM sensor body. Does the resistance measure more than the specified value? | 10 M ohms | Go to Step 11 | Go to Step 9 |
6 |
Does the voltage measure within the specified range? | 0.4 V/260 RPM Over 3.4 V/2,600 RPM | Go to Step 10 | Go to Step 9 |
7 |
Does the DTC reset? | -- | Go to Step 10 | Go to Step 11 |
8 | Repair the sensor wiring harness. Did you complete the repair? | -- | Go to Step 12 | -- |
9 | Replace the sensor. Did you complete the replacement? | -- | Go to Step 12 | -- |
10 | Replace the ECM. Did you complete the replacement? | -- | Go to Step 12 | -- |
11 | Inspect for poor connections at the auxiliary engine RPM sensor and ECM. Repair as necessary. Did you complete the actions? | -- | Go to Step 12 | -- |
12 |
Does the DTC reset? | -- | Go to Step 1 | Go to Step 13 |
13 | Do any other DTCs set? | -- | System OK | |
