Circuit Description
The engine control module (ECM) determines linear wheel speed excessive variation. The wheel speed variation test detects at least one missing edge from the wheel speed sensor signal.
Conditions for Setting the DTC
| • | The wheel speed variation test detects at least one missing edge from the wheel speed sensor signal. |
| • | DTCs P0106, P0107, P0108, P0115, P0116, P0117, P0118, P0122, P0123, P0126, P0201, P0202, P0203, P0204, P0217, P0300, P0351, P0352, P0402, P0404, P0405, P0406, and P1404 are not set. |
| • | Coolant temperature is greater than or equal to 60°C (140°F). |
| • | Vehicle voltage is between 11-16 volts. |
| • | Engine state is run. |
Action Taken When the DTC Sets
| • | The malfunction indicator lamp (MIL) will not illuminate. |
| • | The ECM will store conditions which were present when the diagnostic trouble code (DTC) set as failure records data only. This information will not be stored as freeze frame data. |
| • | A history DTC is stored. |
Conditions for Clearing the MIL/DTC
| • | A history DTC will clear about 40 consecutive warm-up cycles without a fault. |
| • | The DTCs can be cleared by using the scan tool. |
| • | Disconnecting the ECM battery feed for more than 10 seconds |
Diagnostic Aids
Inspect for the following conditions:
| • | Poor connection at the ECM--Inspect the harness connections 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 form damage. If the harness appears to be OK, observe the G sensor display on the scan tool while moving connectors and wiring harnesses related to the sensor. A change in the display will indicate the location of the fault. |
An open pulse width modulation (PWM) serial data line between the ECM and the electronic brake control module (EBCM) will cause this DTC to set.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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The diagnostic system check prompts the technician to complete some basic checks and store the freeze frame and failure records data on the scan tool if applicable. This creates an electronic copy of the data taken when the malfunction occurred. The information is then stored on the scan tool for later reference.
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The replacement ECM must be reprogrammed. Refer to the latest Techline procedure for ECM reprogramming.
Step | Action | Yes | No |
|---|---|---|---|
Did you perform the Diagnostic System Check - Engine Controls? | Go to Step 2 | ||
2 |
Are any additional DTCs set? | Go to Step 3 | |
3 |
Does the scan tool indicate that DTC P1391 failed? | Go to Step 4 | Go to Diagnostic Aids |
4 |
Is the problem found? | Go to Step 5 | Go to Step 6 |
5 | Repair an open or short in the wire between ECM connector terminal K7 and EBCM connector terminal 23. Did you complete the repair? | Go to Step 7 | -- |
Is the repair complete? | Go to Step 7 | -- | |
7 |
Does the scan tool indicate that this diagnostic ran and passed? | Go to Step 8 | Go to Step 2 |
8 | Check if any additional DTCs are set. Are any DTCs displayed that have not been diagnosed? | System OK |
