P1231

DTC P1231: Active Stability Control Plausibility

TECHNICAL DESCRIPTION

- Checks for an abnormal signal of active stability control (ASC) via the CAN communication.

DTC SET CONDITIONS

Check Condition

- Ignition switch is "ON" position.
Judgment Criterion

- A torque demand signal from the active stability control is not normal.

FAIL-SAFE AND BACKUP FUNCTION

- Torque requested by active stability control (ASC) is ignored.

TROUBLESHOOTING HINTS (The most likely causes for this code to be set are:)

- Active stability control system failed.
- ECM failed.

DIAGNOSIS

Required Special Tools:

- MB991958: Scan Tool (M.U.T.-III Sub Assembly)
- MB991824: V.C.I.
- MB991827: USB Cable
- MB991910: Main Harness A

STEP 1. Using scan tool MB991958, read the diagnostic trouble code (DTC).





CAUTION:
To prevent damage to scan tool MB991958, always turn the ignition switch to the "LOCK"
(OFF) position before connecting or disconnecting scan tool MB991958.

(1)Connect scan tool MB991958 to the data link connector.
(2)Turn the ignition switch to the "ON" position.
(3)Read the DTC.
(4)Turn the ignition switch to the "LOCK" (OFF) position.

Q. Is the DTC P1231 set?

YES Go to Step 2.

NO It can be assumed that this malfunction is intermittent. How to Cope With Intermittent Malfunctions.

STEP 2. Using scan tool MB991958, read the diagnostic trouble code
(DTC).

(1)Turn the ignition switch to the "ON" position.

(2)After the DTC has been deleted, read the ASC-DTC.

(3)Turn the ignition switch to the "LOCK" (OFF) position.

Q. Is the ASC-DTC set?

YES Active Stability Control System (ASC).
NO Replace the ECM (Refer to, Removal and Installation Removal and Replacement).