Circuit Description
The engine control module (ECM) determines engine misfire by detecting variations in crankshaft speed. Crankshaft speed variations can also occur when a vehicle is operating over a rough road. The wheel speed sensor produces an alternating current (AC) voltage that increases with wheel speed. The ECM receives a rough road signal from an electronic brake control module (EBCM), if equipped with the anti-lock brake system (ABS). The ABS can determine if the vehicle is on a rough road surface based on the signal from each wheel speed sensor. On vehicles with Non-ABS, a rough road signal is sent to an Analog/Digital (AD) Converter from a wheel speed sensor located at the left front wheel. The AD converter converts the analog signal to a digital signal, and sends the signal to the ECM. The ECM can determine if the vehicle is on a rough road surface based on the signal from the wheel speed sensor. When the ECM detects a rough road condition, misfire diagnostics will be de-activated. If the ECM detects an incorrect wheel speed signal, this DTC sets.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P1382 Wheel Speed Sensor Circuit
Conditions for Running the DTC
| • | DTCs P0501 and P1504 are not set. |
| • | The vehicle speed is between 5-130 km/h (3.1-80.7 mph). |
| • | The wheel speed change is less than 2 km/h (1.2 mph) and vehicle speed change is more than 5 km/h (3 mph). |
| • | DTC P1382 runs continuously once the above conditions are met. |
Conditions for Setting the DTC
The ECM does not detect a rough road signal for more than 10 seconds.
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
The AD converter is located underneath the drivers side dash in the instrument panel (IP) relay center.
If the wheel speed sensor harness is damaged in any way, DO NOT repair the harness.
For an intermittent condition, refer to Intermittent Conditions .
A/D Convertor | |
|---|---|
Ignition 1 Voltage | |
Wheel Speed Sensor Signal | Rough Road Sensor Signal |
Ground | |
Front of Vehicle | |
Test Description
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This step determines if a fault is in the speed sensor signal circuit between the wheel speed sensor and the AD converter.
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This step determines if the wheel speed sensor is unable to generate the proper voltage.
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This step determines if the wheel speed sensor is has an internal resistance condition.
Step | Action | Values | Yes | No | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics | ||||||||||||
1 | Did you perform the Diagnostic System Check - Engine Controls? | -- | Go to Step 2 | |||||||||
2 |
Did DTC P1382 fail this ignition? | -- | Go to Step 4 | Go to Step 3 | ||||||||
Does the DTC fail this ignition? | -- | Go to Step 4 | Go to Diagnostic Aids | |||||||||
4 | Is the vehicle equipped with an Anti-Lock Brake System (ABS)? | -- | Go to Step 12 | Go to Step 5 | ||||||||
5 |
Is the voltage at the specified value? | B+ | Go to Step 6 | Go to Step 18 | ||||||||
6 |
Is the resistance less than the specified value? | 5 ohms | Go to Step 7 | Go to Step 19 | ||||||||
Is the voltage within the specified range? | 4.8-5.2 V | Go to Step 8 | Go to Step 13 | |||||||||
Is the resistance within the specified range? | 1-1.2K ohms | Go to Step 9 | Go to Step 10 | |||||||||
|
Important: If the wheel speed sensor harness is damaged in any way, DO NOT repair the harness.
Notice: Support the lower control arms in the normal horizontal position in order to avoid damage to the drive axles. Do not operate the vehicle in gear with the wheels hanging down at full travel. Is the voltage more than the specified value? | 70 mV | Go to Step 11 | Go to Step 15 | |||||||||
|
Important: If the wheel speed sensor harness is damaged in any way, DO NOT repair the harness.
Is the resistance within the specified range? | 1-1.2K ohms | Go to Step 21 | Go to Step 15 | |||||||||
11 |
Is the resistance less than the specified value? | 5 ohms | Go to Step 14 | Go to Step 20 | ||||||||
12 | Test the circuit between the electronic brake control module (EBCM) and the engine control module (ECM) for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 25 | |||||||||
13 | Test the rough road signal circuit for one of the following conditions:
Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 25 | Go to Step 17 | ||||||||
14 | Test the wheel speed sensor signal circuit for an short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 25 | Go to Step 16 | ||||||||
15 | Test for an intermittent and for a poor connection at the wheel speed sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Repairing Connector Terminals in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 25 | Go to Step 22 | ||||||||
16 | Test for an intermittent and for a poor connection at the AD converter. Refer to Testing for Intermittent Conditions and Poor Connections and Repairing Connector Terminals in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 25 | Go to Step 23 | ||||||||
17 | Test for an intermittent and for a poor connection at the ECM. Refer to Testing for Intermittent Conditions and Poor Connections and Repairing Connector Terminals in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 25 | Go to Step 24 | ||||||||
18 |
Did you complete the repair? | -- | Go to Step 25 | -- | ||||||||
19 | Repair the open or high resistance in the ground circuit of the AD converter. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 25 | -- | ||||||||
20 | Repair the open or high resistance in the ground circuit of the wheel speed sensor. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 25 | -- | ||||||||
21 | Repair the wheel speed sensor signal circuit for one of the following conditions.
Did you complete the repair? | -- | Go to Step 25 | -- | ||||||||
22 | Replace the wheel speed sensor. Did you complete the replacement? | -- | Go to Step 25 | -- | ||||||||
23 | Replace the AD converter. Did you complete the replacement? | -- | Go to Step 25 | -- | ||||||||
24 | Replace the ECM. Refer to Engine Control Module Replacement . Did you complete the replacement? | -- | Go to Step 25 | -- | ||||||||
25 |
Did the DTC fail this ignition? | -- | Go to Step 2 | Go to Step 26 | ||||||||
26 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | -- | System OK | |||||||||
