Circuit Description
The crankshaft position (CKP) sensor signal indicates the crankshaft speed and position. The CKP sensor produces an AC voltage of different amplitude and frequency. The frequency depends on the velocity of the crankshaft, and the AC voltage output depends on the crankshaft position and battery voltage. The CKP sensor works in conjunction with a 58X reluctor wheel attached to the crankshaft. The engine control module (ECM) can synchronize the ignition timing, fuel injector timing, and spark knock control based on the CKP and the CMP sensor inputs. The CKP sensor is also used to detect misfire and tachometer display. The CKP sensor signal circuit and the low reference circuits are connected directly to the ECM. The shielded ground circuit is connected to ground. The circuits between the CKP sensor and the ECM consists of the following circuits:
| • | A signal |
| • | A low reference |
| • | A shielded ground |
If the ECM detects no pulses from the CKP sensor, DTC P0337 sets.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P0337 Crankshaft Position (CKP) Sensor Circuit Low Duty Cycle
Conditions for Running the DTC
| • | The ECM monitors the CKP sensor while the engine is cranking. The ECM uses the CMP sensor to determine if the engine is cranking. If DTC P0341 or P0342 is set, the ECM then monitors the manifold absolute pressure (MAP) sensor signal to determine if the engine is cranking. |
| • | The engine is cranking. |
| • | DTC P0337 runs continuously when the above conditions are met. |
Conditions for Setting the DTC
The ECM detects no CKP pulses during engine cranking for 8 seconds.
Action Taken When the DTC Sets
| • | The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails. |
| • | The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame/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 | Values | Yes | No | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics Connector End View Reference: Engine Control Module Connector End Views or Engine Controls Connector End Views | ||||||||||||||||||
1 | Did you perform the Diagnostic System Check - Engine Controls? | -- | Go to Step 2 | |||||||||||||||
2 | Attempt to start the engine. Does the engine start and run? | -- | Go to Step 3 | Go to Step 4 | ||||||||||||||
3 |
Did the DTC fail this ignition? | -- | Go to Step 4 | Go to Intermittent Conditions | ||||||||||||||
4 |
Is the resistance within the specified range? | 460-620 ohms | Go to Step 5 | Go to Step 6 | ||||||||||||||
5 | Test the CKP sensor circuits between the ECM connector and the CKP connector for a short to voltage or a short to ground. Refer to Circuit Testing in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 14 | Go to Step 9 | ||||||||||||||
6 | Test the CKP sensor circuits between the ECM connector and the CKP connector for the following conditions:
Refer to Circuit Testing in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 14 | Go to Step 7 | ||||||||||||||
7 | Test for an intermittent and for a poor connection at the ECM. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring System. Did you find and correct the condition? | -- | Go to Step 14 | Go to Step 8 | ||||||||||||||
8 | Test for an intermittent and for a poor connection at the CKP sensor. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 14 | Go to Step 10 | ||||||||||||||
9 | Test for shorted terminals and poor connections at the ECM. 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 | ||||||||||||||
10 |
Important: If the sensor lead is damaged in any way, DO NOT repair the lead.
Did you find and correct the conditions? | -- | Go to Step 14 | Go to Step 11 | ||||||||||||||
11 |
Important: If the reluctor wheel is also damaged, replace the CKP sensor and the crankshaft. Inspect the CKP reluctor wheel for the following conditions:
Refer to Crankshaft and Bearing Cleaning and Inspection in Engine Mechanical - 2.0L (L34GMDAT). Did you find and correct the condition? | -- | Go to Step 14 | Go to Step 12 | ||||||||||||||
12 | Replace the CKP sensor. Refer to Crankshaft Position Sensor Replacement . Did you complete the replacement? | -- | Go to Step 14 | -- | ||||||||||||||
13 | Replace the ECM. Refer to Engine Control Module Replacement . 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? | -- | System OK | |||||||||||||||
