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DTC B16A8 Tail light(LH) circuit short <Short circuit in the position light (LH) circuit, taillight (LH) circuit or the license plate light circuit>
 
 
caution
  • Before replacing the ECU, ensure that the power supply circuit, the ground circuit and the communication circuit are normal.
 
 
DIAGNOSTIC FUNCTION
When a short circuit is detected in the following light circuit, the ETACS-ECU sets DTC B16A8.
  • Taillight
  • License light
  • Position light
 
 
TROUBLE JUDGMENT
The problem detection of taillight is made based on the digital feed back signal (input signal to ETACS-ECU) which operates the taillight. When the ignition switch is "ON", the ETACS-ECU determines the taillight circuit state from the load placed on the line. After 100 ms has elapsed since the start of the check, the ETACS-ECU performs a sampling with each 10 ms. If an abnormality is detected, it increases the counter by 2, and when no abnormality is detected, it decreases the counter by 1. Once the counter reaches "10," the ETACS-ECU sets DTC B16A8 if no load is detected.
 
 
TROUBLESHOOTING HINTS
  • Malfunction of headlight assembly (position/side marker: LH)
  • Malfunction of rear combination light unit (tail/side marker: LH)
  • Malfunction of taillight unit (LH)
  • Malfunction of license plate light bulbs
  • Damaged harness wires and connectors
  • Malfunction of the ETACS-ECU
 
 
DIAGNOSIS
Required Special Tools:
  • MB992006: Extra fine probe
  • MB991223: Harness set
STEP 1. Resistance measurement at the rear combination light (tail/side marker: LH) connector (power supply terminal).
(1) Disconnect the connector, and measure at the wiring harness side.
(2) Measure the resistance between the rear combination light (tail/side marker: LH) connector (power supply terminal) and body ground.
OK: Is the measured resistance 2 ohms or less
Is the check result normal?
Go to Step 3.
Go to Step 2.
 
STEP 2. Check of short to ground and power supply in (TAL2) lines between the rear combination light (tail/side marker: LH) connector and ETACS-ECU connector.
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), read the DTC again.
(1)
cautionTo prevent damage to scan tool (M.U.T.-IIISE), always turn the ignition switch to the "LOCK" (OFF) position 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 ignition switch from "LOCK" (OFF) position to "ON" position.
(4) Check if DTC 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), read the DTC again.
(1) Erase the DTC.
(2) Disconnect the rear combination light (tail/side marker: LH) connector.
(3) Lighting operation of a taillight is performed.
(4) Check if DTC is set.
Is the DTC set?
Go to Step 5.
Replace the rear combination light unit (LH).
 
STEP 5. Resistance measurement at the taillight (LH) connector (power supply terminal).
(1) Disconnect the connector, and measure at the wiring harness side.
(2) Measure the resistance between the taillight (LH) connector (power supply terminal) and the body ground.
OK: Is the measured resistance 2 ohms or less
Is the check result normal?
Go to Step 7.
Go to Step 6.
 
STEP 6. Check of short to ground and power supply in (TAL2) lines between the taillight (LH) connector and ETACS-ECU connector.
Is the check result normal?
Go to Step 7.
Repair the connector(s) or wiring harness.
 
STEP 7. Using scan tool (M.U.T.-IIISE), read the DTC again.
(1) Erase the DTC.
(2) Turn the ignition switch from "LOCK" (OFF) position to "ON" position.
(3) Check if DTC is set.
Is the DTC set?
Go to Step 8.
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 8. Using scan tool (M.U.T.-IIISE), read the DTC again.
(1) Erase the DTC.
(2) Disconnect the taillight (LH) connector.
(3) Lighting operation of a taillight is performed.
(4) Check if DTC is set.
Is the DTC set?
Go to Step 9.
Replace the taillight unit (LH).
 
STEP 9. Check the license plate light bulbs.
Check the continuity at the license light bulb (RH) or (LH) to confirm whether it is normal.
Is the check result normal?
Go to Step 10.
Replace the rear combination light bulb (RH) or (LH).
 
STEP 10. Resistance measurement at the license plate light (RH), or (LH) connector (power supply terminal).
(1) Disconnect the connector, and measure at the wiring harness side.
(2) Measure the resistance between the license plate light (RH) or (LH) connector (power supply terminal) and the body ground.
OK: Is the measured resistance 2 ohms or less
Is the check result normal?
Go to Step 12.
Go to Step 11.
 
STEP 11. Check of short to ground and power supply in (TAL2) lines between the license plate light (RH) or (LH) connector and ETACS-ECU connector.
Is the check result normal?
Go to Step 12.
Repair the connector(s) or wiring harness.
 
STEP 12. Using scan tool (M.U.T.-IIISE), read the DTC again.
(1) Erase the DTC.
(2) Turn the ignition switch from "LOCK" (OFF) position to "ON" position.
(3) Check if DTC is set.
Is the DTC set?
Go to Step 13.
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 13. Resistance measurement at the headlight assembly (position/side marker: LH) connector (power supply terminal).
(1) Disconnect the connector, and measure at the wiring harness side.
(2) Measure the resistance between the headlight assembly (position/side marker: LH) connector (power supply terminal) and the body ground.
OK: Is the measured resistance 2 ohms or less
Is the check result normal?
Go to Step 15.
Go to Step 14.
 
STEP 14. Check of short to ground and power supply in (TAR1) lines between the headlight assembly (position/side marker: LH) connector and ETACS-ECU connector.
Is the check result normal?
Go to Step 15.
Repair the connector(s) or wiring harness.
 
STEP 15. Using scan tool (M.U.T.-IIISE), read the DTC again.
(1) Erase the DTC.
(2) Turn the ignition switch from "LOCK" (OFF) position to "ON" position.
(3) Check if DTC is set.
Is the DTC set?
Go to Step 16.
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 16. Using scan tool (M.U.T.-IIISE), read the DTC again.
(1) Erase the DTC.
(2) Disconnect the headlight (position/side marker: LH) connector.
(3) Lighting operation of a position light is performed.
(4) Check if DTC is set.
Is the DTC set?
Replace the ETACS-ECU.
Replace the headlight assembly (LH).