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DTC B16A7: Taillight (RH) circuit short <Short circuit in the position light (RH) circuit or the taillight (RH) circuit>
 
 
caution
  • Before replacing the ECU, ensure that the power supply circuit, the ground circuit and the communication circuit are normal.
  • When the ETACS-ECU of vehicles without KOS is replaced, the encrypted code of the ignition key needs to be registered to the ETACS-ECU. (If the encrypted code is not registered, the engine cannot be started. Register the encrypted code as described in Immobilizer System - How to Register Key ID .)
 
 
DIAGNOSTIC FUNCTION
When a short circuit is detected in the position light circuit or the taillight circuit, the ETACS-ECU sets DTC No. B16A7.
 
 
TROUBLE JUDGMENT
The problem detection of taillight is made based on the digital feedback 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 No. B16A7 if no load is detected.
 
 
TROUBLESHOOTING HINTS
  • The headlight assembly (RH) may be defective
  • The rear combination light assembly (RH) may be defective
  • The taillight assembly (RH) may be defective
  • The ETACS-ECU may be defective
  • The wiring harness or connectors may have loose, corroded, or damaged terminals, or terminals pushed back in the connector
 
 
DIAGNOSIS
Required Special Tools:
  • MB992006: Extra fine probe
  • MB991223: Harness set
STEP 1. Determine a trouble spot.
Which of light does not work?
: Go to Step 2.
: Go to Step 7.
: Go to Step 13.
 
STEP 2. Resistance measurement at the headlight assembly (position/side marker: RH) connector (ground terminal).
(1) Disconnect the connector, and measure at the wiring harness side.
(2) Measure the resistance between the headlight assembly (position/side marker: RH) connector (ground terminal) and ground.
OK: The resistance should be 2 ohms or less
Is the check result normal?
Go to Step 4.
Go to Step 3.
 
STEP 3. Check of open circuit in ground line between the headlight assembly (position/side marker: RH) connector and ground.
Is the check result normal?
Go to Step 5.
Repair the connector(s) or wiring harness.
 
STEP 4. Check of short to power supply, short to ground, and open circuit in TAR1 line between the headlight assembly (position/side marker: RH) connector and ETACS-ECU connector.
Is the check result normal?
Go to Step 5.
Repair the connector(s) or wiring harness.
 
STEP 5. Using scan tool (M.U.T.-III), Check whether the diagnostic trouble code is set again.
(1)
cautionTo prevent damage to scan tool (M.U.T.-III), always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool (M.U.T.-III).
Connect scan tool (M.U.T.-III). Refer to "How to connect Scan Tool (M.U.T.-III) ."
(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 6.
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 6. Substitute a known good headlight assembly (RH), and recheck for diagnostic trouble code.
(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?
Replace the ETACS-ECU.
Replace the headlight assembly (RH).
 
STEP 7. Check the rear combination light socket.
Check the continuity at the rear combination light socket to confirm whether it is normal.
Is the check result normal?
Go to Step 8.
Replace the rear combination light socket (RH).
 
STEP 8. Resistance measurement at the rear combination light (taillight/side marker: RH) connector (ground terminal).
(1) Disconnect the connector, and measure at the wiring harness side.
(2) Measure the resistance between the rear combination light (taillight/side marker: RH) connector (ground terminal) and ground.
OK: The resistance should be 2 ohms or less
Is the check result normal?
Go to Step 10.
Go to Step 9.
 
STEP 9. Check of open circuit in ground line between the rear combination light (taillight/side marker: RH) connector and ground
Is the check result normal?
Go to Step 11.
Repair the connector(s) or wiring harness.
 
STEP 10. Check of short to power supply, short to ground, and open circuit in TAR2 line between the rear combination light (taillight/side marker: RH) connector and ETACS-ECU connector.
Is the check result normal?
Go to Step 11.
Repair the connector(s) or wiring harness.
 
STEP 11. Using scan tool (M.U.T.-III), Check whether the diagnostic trouble code is set again.
(1)
cautionTo prevent damage to scan tool (M.U.T.-III), always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool (M.U.T.-III).
Connect scan tool (M.U.T.-III). Refer to "How to connect Scan Tool (M.U.T.-III) ."
(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 12.
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 12. Substitute a known good rear combination light assembly (RH), and recheck for diagnostic trouble code.
(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?
Replace the ETACS-ECU.
Replace the rear combination light assembly (RH).
 
STEP 13. Resistance measurement at the taillight (RH) connector (ground terminal).
(1) Disconnect the connector, and measure at the wiring harness side.
(2) Measure the resistance between the taillight (RH) connector (ground terminal) and the ground.
OK: The resistance should be 2 ohms or less
Is the check result normal?
Go to Step 15.
Go to Step 14.
 
STEP 14. Check of open circuit in ground lines between the taillight (RH) connector and ground.
Is the check result normal?
Go to Step 16.
Repair the connector(s) or wiring harness.
 
STEP 15. Check of short to power supply, short to ground, and open circuit in TAR2 line between the taillight (RH) connector and ETACS-ECU connector.
Is the check result normal?
Go to Step 16.
Repair the connector(s) or wiring harness.
 
STEP 16. Using scan tool (M.U.T.-III), Check whether the diagnostic trouble code is set again.
(1)
cautionTo prevent damage to scan tool (M.U.T.-III), always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool (M.U.T.-III).
Connect scan tool (M.U.T.-III). Refer to "How to connect Scan Tool (M.U.T.-III) ."
(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 17.
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 17. Substitute a known good taillight assembly (RH), and recheck for diagnostic trouble code.
(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?
Replace the ETACS-ECU.
Replace the taillight assembly (RH).