DTC 21
DIAGNOSTIC TROUBLE CODE PROCEDURESDTC 21: Height Sensor Abnormality (Rear)
CAUTION: Before replacing the ECU, ensure that the communication circuit is normal.
Height Sensor (Rear) Circuit (Part 1):
Height Sensor (Rear) Circuit (Part 2):
TROUBLE JUDGMENT
When the headlight automatic leveling-ECU receives an abnormal voltage signal from the rear height sensor, DTC 21 is set.
TECHNICAL DESCRIPTION (COMMENT)
The rear height sensor, the headlight automatic leveling-ECU, or wiring harness and connectors between the two may have a problem.
TROUBLESHOOTING HINTS
- Malfunction of the rear height sensor
- Malfunction of the headlight automatic leveling-ECU
- The wiring harness or connectors may have loose, corroded, or damaged terminals, or terminals pushed back in the connector
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. Check rear height sensor connector D-118 for loose, corroded or damaged terminals, or terminals pushed back in the connector.
Q: Is rear height sensor connector D-118 in good condition?
YES : Go to Step 2.
NO : Repair the damaged parts.
STEP 2. Check headlight automatic leveling-ECU connector C-110 for loose, corroded or damaged terminals, or terminals pushed back in the connector.
Q: Is headlight automatic leveling-ECU connector C-110 in good condition?
YES : Go to Step 3.
NO : Repair the damaged parts.
STEP 3. Check the wiring harness between rear height sensor connector D-118 (terminal No. 1/2/3) and the headlight automatic leveling-ECU connector C-110 (terminal No 16/18/20).
NOTE: Before the wiring harness check, check the intermediate connectors C-129 and D-117, and then repair that if necessary.
Q: Is wiring harness between rear height sensor connector D-118 (terminal No. 1/2/3) and the headlight automatic leveling-ECU connector C-110 (terminal No 16/18/20) in good condition?
YES : Go to Step 4.
NO : Repair the wiring harness.
STEP 4. Check the rear height sensor.
Check that the rear height sensor is normal. Rear Height Sensor Check
Q: Does the rear height sensor work normal?
YES : Go to Step 5.
NO : Replace the rear height sensor.
STEP 5. Using scan tool MB991958, Check whether the diagnostic trouble code is reset.
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."How to connect scan tool." Scan Tool Connecting
2. Turn the ignition switch to the "ON" position.
3. Erase the DTC.
4. Turn the ignition switch from "LOCK" (OFF) position to "ON" position.
5. Check if DTC is set.
Q: Is DTC 21 set?
YES : Replace the headlight automatic leveling-ECU.
NO : The trouble, such as a poor connector connection from the rear height sensor to headlight automatic leveling-ECU or an open circuit of wiring harness, can be an intermittent malfunction. (Refer to general (body and chassis) - How to use Troubleshooting/inspection Service Points - How to cope with Intermittent Malfunction.)