Circuit Description
WARNING: This page is about a different car, the 2004 Buick Regal. However, it is still accessible from the selected car via links, so may be relevant.
The ignition control module (ICM) monitors the crankshaft position (CKP) sensor sync signal when the engine is cranking. The CKP sync signal is passed from the CKP sensor to the ICM on the CKP sensor 2 signal circuit. The CKP sync signal is used to determine the correct cylinder pair and initiate the ignition coil firing sequence. The 18X reference pulses are passed from the CKP sensor to the ICM on the CKP sensor 1 signal circuit. The 18X reference pulses are used for fuel injection and ignition control. After the ICM receives both signals, the ICM passes the 18X and 3X reference signals to the powertrain control module (PCM). The camshaft position sensor and the CKP sensor share a 12-volt reference and a low reference circuit. The CKP sensor consists of the following circuits:
- A 12-volt reference circuit
- A low reference circuit
- A CKP sensor 1 signal circuit
- A CKP sensor 2 signal circuit
Crankshaft Position Sensor (CKP) System Diagnosis
| Step | Action | Values | Yes | No |
|---|---|---|---|---|
| Schematic Reference: Engine Controls Schematics Connector End View Reference: Engine Controls Connector End Views or Powertrain Control Module (PCM) Connector End Views |
||||
| 1 | Did you perform the Diagnostic System Check-Engine Controls? | - | Go to Step 2 | Go to Diagnostic System Check - Engine Controls |
| 2 | Attempt to start the engine. Does the engine start and run? |
- | Go to Intermittent Conditions | Go to Step 3 |
| 3 |
|
- | Go to Step 12 | Go to Step 4 |
| 4 |
|
B+ | Go to Step 5 | Go to Step 14 |
| 5 | Test the ignition 1 voltage circuit of the ICM for high resistance. Refer to Circuit Testing
and Wiring Repairs
in Wiring Systems. Is the resistance greater than the specified value? |
1 Ω | Go to Step 26 | Go to Step 6 |
| 6 | Measure the voltage between the ignition 1 voltage circuit and the ground circuit of the ICM with a DMM. Refer to Circuit Testing
in Wiring Systems. Is the voltage within the specified value? |
B+ | Go to Step 7 | Go to Step 15 |
| 7 |
|
1 V | Go to Step 16 | Go to Step 8 |
| 8 | Measure the voltage between the 12-volt reference circuit and the low reference circuit of the CKP sensor with a DMM. Refer to Circuit Testing
in Wiring Systems. Is the difference between the measured voltage and the system voltage more than the specified value? |
1 V | Go to Step 17 | Go to Step 9 |
| 9 | Test for high resistance in the 12-volt reference circuit and the low reference circuit of the CKP sensor. Refer to Circuit Testing
and Wiring Repairs
in Wiring Systems. Did you find and correct the condition? |
- | Go to Step 31 | Go to Step 10 |
| 10 | Measure the voltage between the CKP sensor 1 signal circuit and the low reference circuit of the CKP sensor with a DMM. Refer to Circuit Testing
in Wiring Systems. Is the voltage within the specified range? |
4-8 V | Go to Step 23 | Go to Step 11 |
| 11 | Is the voltage more than the specified range? | 4-8 V | Go to Step 18 | Go to Step 19 |
| 12 | Measure the voltage between the CKP sensor 2 signal circuit and the low reference circuit of the CKP sensor with a DMM. Refer to Circuit Testing
in Wiring Systems. Is the voltage within the specified range? |
4-8 V | Go to Step 22 | Go to Step 13 |
| 13 | Is the voltage more than the specified range? | 4-8 V | Go to Step 20 | Go to Step 21 |
| 14 | Repair the ignition 1 voltage circuit for an open and for a short to ground. Refer to Circuit Testing
and Wiring Repairs
in Wiring Systems. Did you complete the repair? |
- | Go to Step 31 | - |
| 15 | Repair the ground circuit for an open or high resistance. Refer to Circuit Testing
and Wiring Repairs
in Wiring Systems. Did you complete the repair? |
- | Go to Step 31 | - |
| 16 | Test the 12-volt reference circuit for an open or a short to ground. Refer to Circuit Testing
and Wiring Repairs
in Wiring Systems. Did you find and correct the condition? |
- | Go to Step 31 | Go to Step 24 |
| 17 | Test the low reference circuit for an open and for high resistance. Refer to Circuit Testing
and Wiring Repairs
in Wiring Systems. Did you find and correct the condition? |
- | Go to Step 31 | Go to Step 24 |
| 18 | Test the CKP sensor 1 signal circuit 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 31 | Go to Step 24 |
| 19 | Test the CKP sensor 1 signal circuit for the following conditions:
Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? |
- | Go to Step 31 | Go to Step 24 |
| 20 | Test the CKP sensor 2 signal circuit 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 31 | Go to Step 24 |
| 21 | Test the CKP sensor 2 signal circuit for an open or a short to ground. Refer to Circuit Testing
and Wiring Repairs
in Wiring Systems. Did you find and correct the condition? |
- | Go to Step 31 | Go to Step 24 |
| 22 | Test the CKP sensor 2 signal circuit for high resistance. Refer to Circuit Testing
and Wiring Repairs
in Wiring Systems. Did you find and correct the condition? |
- | Go to Step 31 | Go to Step 27 |
| 23 | Test the CKP sensor 1 signal circuit for high resistance, and for the CKP sensor signal 1 circuit shorted to the CKP sensor signal 2 circuit. Refer to Circuit Testing
and Wiring Repairs
in Wiring Systems. Did you find and correct the condition? |
- | Go to Step 31 | Go to Step 27 |
| 24 | Test for an intermittent and for a poor connection at the CKP sensor. 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 31 | Go to Step 25 |
| 25 | Test for an intermittent and for a 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 31 | Go to Step 30 |
| 26 | Repair the high resistance in the ignition 1 voltage circuit. Refer to Wiring Repairs
in Wiring Systems. Did you complete the repair? |
- | Go to Step 31 | - |
| 27 |
|
- | Go to Step 31 | Go to Step 28 |
| 28 | Inspect the crankshaft reluctor wheel for the following conditions:
Refer to Crankshaft and Bearings Cleaning and Inspection in Engine Mechanical. Did you find and correct the condition? |
- | Go to Step 31 | Go to Step 29 |
| 29 | Replace the CKP sensor. Refer to Crankshaft Position (CKP) Sensor Replacement
. Did you complete the replacement? |
- | Go to Step 31 | - |
| 30 | Replace the ICM. Refer to Ignition Control Module Replacement
. Did you complete the replacement? |
- | Go to Step 31 | - |
| 31 |
|
- | System OK | Go to Step 2 |