Circuit Description
The camshaft position (CMP) sensor is a Hall-effect type sensor. The sensor produces one signal for each revolution of the camshaft in order to control the sequential fuel injection. There are no direct circuits to the powertrain control module (PCM). All of the circuits are between the CMP sensor and the ignition control module (ICM). These circuits are the CMP signal circuit, the 12-volt reference circuit, and the low reference circuit. The PCM compares the CMP sensor signal to the number of 3X, low-resolution, engine speed signals generated by the ICM. The normal ratio of 3X signals is 6-to-1. If the PCM receives an incorrect number of CMP sensor signals, this DTC sets.
Conditions for Running the DTC
The engine is running, and 3X reference pulses are being received.
Conditions for Setting the DTC
The PCM does not receive CMP sensor reference pulses during one rotation of the camshaft.
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. |
Diagnostic Aids
Inspect for the following conditions:
| • | Any secondary ignition wires arcing to a wiring harness--Inspect the secondary ignition wires for carbon tracking or for other signs of damage. |
| • | A faulty ignition coil--Remove the ignition coils and inspect the ignition control module and the coils for cracks, for carbon tracking, or for other signs that indicate that the coil secondary circuit is arcing to the ICM or to the ICM wiring harness. Refer to Ignition Coil Replacement . |
If the condition is suspected of being intermittent, refer to Intermittent Conditions .
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
This step verifies that the fault is present.
-
This step determines if the fault is caused by a missing camshaft magnet or by a faulty PCM. The voltage measured in this step should be near 4 volts, and decrease to near 0 volts when the CMP sensor interfaces with the camshaft magnet.
Step | Action | Values | Yes | No | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics | ||||||||||||
1 |
Important:: If the engine cranks but will not run, refer to Engine Cranks but Does Not Run . Did you perform the Diagnostic System Check-Engine Controls? | -- | Go to Step 2 | |||||||||
2 |
Is the CMP sensor input signal present? | -- | Go to Step 3 | Go to Step 4 | ||||||||
Does the DTC set again? | -- | Go to Step 4 | Go to Diagnostic Aids | |||||||||
4 |
Important: If voltage measures 0 volts, bump over the engine in order to ensure the CMP sensor magnet is not located under the CMP sensor at the time of this test. Is the voltage near the specified value? | 5 V | Go to Step 5 | Go to Step 6 | ||||||||
5 |
Important:
Does the voltage toggle from 5 volts to 0 volts when the magnet is placed on the sensor? | -- | Go to Step 17 | Go to Step 9 | ||||||||
6 | Does the voltage on the camshaft position signal circuit measure more than the specified value? | 5 V | Go to Step 8 | Go to Step 7 | ||||||||
7 |
Did you find and correct the condition? | -- | Go to Step 25 | Go to Step 14 | ||||||||
8 |
Did you find and correct the condition? | -- | Go to Step 25 | Go to Step 19 | ||||||||
9 |
Does the voltage measure near the specified value? | B+ | Go to Step 10 | Go to Step 13 | ||||||||
10 | Measure the voltage from the signal circuit of the CMP sensor to the low reference circuit of the CMP sensor with a DMM. Does the voltage measure within the specified range? | 5-7 V | Go to Step 11 | Go to Step 12 | ||||||||
11 |
Does the voltage switch from 0 volts to 5 volts when the test lamp is repeatedly touched to the CMP sensor signal circuit? | -- | Go to Step 16 | Go to Step 15 | ||||||||
12 | Test for the following conditions:
Refer to Circuit Testing and to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 25 | Go to Step 15 | ||||||||
13 | Test the following circuits for an open between the ICM and the CMP sensor:
Refer to Circuit Testing and to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 25 | Go to Step 15 | ||||||||
14 | Test for an open in the camshaft position signal circuit between the PCM and the ICM. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 25 | Go to Step 15 | ||||||||
15 | Inspect for faulty connections at the ICM. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 25 | Go to Step 18 | ||||||||
16 | Inspect for faulty connections at the CMP sensor. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 25 | Go to Step 20 | ||||||||
17 | Inspect for faulty connections at the PCM. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 25 | Go to Step 21 | ||||||||
18 |
Did you find and correct the condition? | -- | Go to Step 25 | Go to Step 19 | ||||||||
19 | Replace the ICM. Refer to Ignition Control Module Replacement . Did you complete the replacement? | -- | Go to Step 25 | -- | ||||||||
20 | Replace the CMP sensor. Refer to Camshaft Position Sensor Replacement . Did you complete the replacement? | -- | Go to Step 25 | -- | ||||||||
21 | Inspect for the following conditions:
Did you find and correct the condition? | -- | Go to Step 25 | Go to Step 22 | ||||||||
Does the voltage toggle between the specified values? | 0 V 5 V | Go to Step 23 | Go to Step 24 | |||||||||
23 | Replace the PCM. Refer to Powertrain Control Module Replacement . Did you complete the replacement? | -- | Go to Step 25 | -- | ||||||||
24 | Replace a faulty or missing CMP sensor magnet. Did you complete the replacement? | -- | Go to Step 25 | -- | ||||||||
25 |
Does the diagnostic test run and pass? | -- | Go to Step 26 | Go to Step 2 | ||||||||
26 | With a scan tool, observe the stored information, Capture Info. Does the scan tool display any DTCs that you have not diagnosed? | -- | System OK | |||||||||
