DTC B1B8D: Driver Seat Slide Sensor Open Circuit

caution

If DTC B1B8D is set in the occupant classification-ECU, always diagnose the CAN main bus lines.

CIRCUIT OPERATION

The seat slide sensor sets the current value Hi or Low determined by the seat position.
The occupant classification-ECU determines the seat position according to the current value from the seat slide sensor.

DTC SET CONDITIONS

This DTC is set if there is abnormal resistance between the input terminals of the seat slide sensor. The most likely causes for this code to be set are the followings:

Open circuit in the seat slide sensor or harness

TROUBLESHOOTING HINTS

Open circuit in the seat slide sensor circuit
Disengaged seat slide sensor connector
Improper connector contact
Malfunction of the seat slide sensor
Malfunction of the occupant classification-ECU

DIAGNOSIS

Required Special Tools:

MB991958: Scan Tool (M.U.T.-III Sub Assembly)

MB991824: Vehicle Communication Interface (V.C.I.)
MB991827: M.U.T.-III USB Cable
MB991910: M.U.T.-III Main Harness A (Vehicles with CAN communication system)

STEP 1. Using scan tool MB991958, diagnose the CAN bus line.

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. Refer to "How to connect the scan tool

."
(2)Turn the ignition switch to the "ON" position.
(3)Diagnose the CAN bus line.
(4)Turn the ignition switch to the "LOCK" (OFF) position.

Q. Is the CAN bus line found to be normal?

Go to Step 2.

Repair the CAN bus line (Refer to GROUP 54C, Diagnosis

STEP 2. Recheck for diagnostic trouble code.

Check again if the DTC is set.

(1)Erase the DTC.

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

(3)Check if the DTC is set.

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

Q. Is the DTC set?

	Go to Step 3.

	There is an intermittent malfunction such as poor engaged connector(s) or open circuit (Refer to GROUP 00, How to Cope with Intermittent Malfunction ).

STEP 3. Check the harness for open circuit between occupant classification-ECU connector D-35-2 (terminal No.27 and 29) and the seat slide sensor connector D-28 (terminal No.2 and 1).

(1)Disconnect occupant classification-ECU connector D-35-2 and seat slide sensor connector D-28.

(2)

caution

Do not insert a test probe into the terminal from its front side directly, as the connector contact pressure may be weakened.

Check for continuity between the following terminals. It should be less than 2 ohms.

Occupant classification-ECU connector D-35-2 (terminal No.27) and the seat slide sensor connector D-28 (terminal No.2)
Occupant classification-ECU connector D-35-2 (terminal No.29) and the seat slide sensor connector D-28 (terminal No.1)

Q. Does continuity exist?

Go to Step 4.

Repair the harness wires between occupant classification-ECU connector D-35-2 and seat slide sensor connector D-28.

STEP 4. Recheck for diagnostic trouble code.

Check again if the DTC is set to the occupant classification-ECU.

(1)Erase the DTC.

(2)Turn the ignition switch from "LOCK" (OFF) position to "ON" position.

(3)Check if DTC is set.

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

Q. Is the DTC B1B8Dset?

	Replace the front seat cushion frame (LH) (Refer to GROUP 52A, Front seat assembly ) <Except RALLIART> or replace the slide adjuster (LH) (Refer to GROUP 52A, Front Seat Assembly ) <RALLIART>. Then go to Step 5.

	There is an intermittent malfunction such as poor engaged connector(s) or open circuit (Refer to GROUP 00, How to Cope with Intermittent Malfunction ).

STEP 5. Recheck for diagnostic trouble code.

Check again if the DTC is set to the occupant classification-ECU.

(1)Erase the DTC.

(2)Turn the ignition switch from "LOCK" (OFF) position to "ON" position.

(3)Check if DTC is set.

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

Q. Is the DTC set?

	Replace the front seat cushion frame (RH) (Refer to GROUP 52A, Front seat assembly ) <Except RALLIART> or replace the slide adjuster (RH) (Refer to GROUP 52A, Front Seat Assembly ) <RALLIART>.

	There is an intermittent malfunction such as poor engaged connector(s) or open circuit (Refer to GROUP 00, How to Cope with Intermittent Malfunction ).