• | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
• | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
• | Diagnostic Procedure Instructions provides an overview of each diagnostic category. |
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 from a wheel speed sensor located at the left front wheel 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 disabled.
• | DTCs P0106, P0107, P0108, P0117, P0118, P0122, P0123, P0201, P0202, P0203, P0204, P0300, P0351,P0352, P0402, P0404, P0405, P0406, and P1404 are not set. |
• | The engine is running. |
• | The engine coolant temperature is greater than 60°C (140°F). |
• | The ignition 1 voltage is between 11-16 volts. |
• | The DTCs run continuously once the above condition are met. |
The ECM detects an invalid rough road signal from the wheel speed sensor.
The ECM detects an invalid rough road signal from the EBCM.
DTC P1396 and P1397 are Type C DTCs
DTC P1396 and P1397 are Type C DTCs
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Engine running, DTCs P1396 or P1397 should not set.
Important: If the ABS lamp is illuminated, the ABS system must be diagnosed prior to using this diagnostic procedure. Refer to Diagnostic System Check - Vehicle .
⇒ | If greater than 5.2 volts, test the rough road signal circuit for a short to voltage . If the circuit/connections test normal, replace the ECM. |
⇒ | If less than 4.8 volts, test the rough road signal circuit for a short to ground or an open. If the circuit/connections test normal, replace the ECM. |
⇒ | If greater than 5 ohms, test the low reference circuit of the wheel speed sensor for an open/high resistance. If the circuit/connections test normal, replace the ECM. |
Important: This procedure is for vehicle without ABS. 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.
⇒ | If less than 70 mV AC, replace the wheel speed sensor. |
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
Control Module References for engine control module or electronic brake control module replacement, setup, and programming