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DTC B1E1C Stoplight Overload or Short Circuit
 
 
cautionBefore replacing the ECU, ensure that the power supply circuit, the ground circuit and the communication circuit are normal.
 
 
TROUBLE JUDGMENT
If the stop light wiring harness wires are shorted, the ETACS-ECU will set DTC No. B1E1C.
 
 
TECHNICAL DESCRIPTION (COMMENT)
DTC No. B1E1C will be set if the ETACS-ECU detects a short between itself and any of the stop lights.
 
 
PROBABLE CAUSES
  • The rear combination light unit may be defective
  • The high-mounted stop light assembly may be defective
  • The stop light circuit fails
  • The ETACS-ECU may be defective
 
 
DIAGNOSIS
Required Special Tools:
  • MB991223: Harness Set
  • MB992006: Extra Fine Probe
STEP 1. Check the following wiring harness.
Check the wiring harness for short circuit between the following connectors:
  • Check of short circuit in STLO line high-mounted stop light connector and ETACS-ECU connector.
  • Check of short circuit in STLO line rear combination light (Stop: RH) connector and ETACS-ECU connector.
  • Check of short circuit in STLO line rear combination light (Stop: LH) connector and ETACS-ECU connector.
Is the check result normal?
Go to Step 2.
Repair the connector(s) or wiring harness.
 
STEP 2. Check the following wiring harness.
Check the wiring harness for ground circuit between the following connectors:
  • Check of short circuit in ground line high-mounted stop light connector and body ground.
  • Check of short circuit in ground line rear combination light (Stop: RH) connector and body ground.
  • Check of short circuit in ground line rear combination light (Stop: LH) connector and body ground.
Is the check result normal?
Go to Step 3.
Repair the connector(s) or wiring harness.
 
STEP 3. Using scan tool (M.U.T.-IIISE), Check whether the DTC is set again.
Check again if the DTC No.B1E1C is set in the ETACS-ECU.
(1)
cautionTo prevent damage to scan tool (M.U.T.-IIISE), always turn off the power supply mode of the electric motor switch before connecting or disconnecting scan tool (M.U.T.-IIISE).
Connect scan tool (M.U.T.-IIISE). Refer to "How to connect Scan Tool (M.U.T.-IIISE) ."
(2) Erase the DTC.
(3) Turn the electric motor switch from the "OFF" position to the "ON" position.
(4) Depress the brake pedal.
(5) Check the DTC No.B1E1C is set.
Is the DTC set?
Go to Step 4.
The trouble can be an intermittent malfunction (Refer to GROUP 00 - How to use Troubleshooting/inspection Service Points - How to Cope with Intermittent Malfunction ).
 
STEP 4. Using scan tool (M.U.T.-IIISE), check whether the DTC is set again.
Check again if the DTC No.B1E1C is set in the ETACS-ECU.
(1) Erase the DTC.
(2) Disconnect connector (a).
  1. High-mounted stop light connector
  2. Rear combination light (Stop: RH) connector
  3. rear combination light (Stop: LH) connector
(3) Turn the electric motor switch from the "OFF" position to the "ON" position.
(4) Depress the brake pedal.
(5) Check the DTC No.B1E1C is set.
(6) Repeat steps (1) to (5) for parts (b) to (d) to determine a fault cause.
Is the DTC set?
Replace the ETACS-ECU.
Replace a defective light (the rear combination light unit or the high-mounted stop light assembly).