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DTC U1515 No bus activity error for LIN
 
 
cautionBefore replacing the ECU, ensure that the power supply circuit, the ground circuit and the communication circuit are normal.
 
 
TROUBLE JUDGMENT
The ETACS-ECU will set DTC U1515 when no communication has been carried out for more than a certain period after it received last valid data.
 
 
PROBABLE CAUSES
  • Malfunction of the ETACS-ECU
  • Malfunction of the slave ECU
  • LIN bus lines shorted to power supply
  • LIN bus lines shorted to ground
 
 
DIAGNOSIS
Required Special Tools:
  • MB991223: Harness Set
  • MB992006: Extra Fine Probe
STEP 1. Measure the voltage at the LIN bus lines.
Check the LIN bus lines for short to power supply.
(1) Disconnect all the connectors leading to the LIN bus lines.
(2) Turn the ignition switch from "LOCK" (OFF) to "ON" position.
(3) Measure the voltage between the column switch connector (DATA terminal) and the body ground.
  • The voltmeter needle does not swing.
noteIf the LIN bus lines are short to power supply, the voltmeter indicates a constant value.
(4) Measure the voltage between the sunroof motor assembly connector (LIN2 terminal) and the body ground. <Vehicles with sunroof>
  • The voltmeter needle does not swing.
noteIf the LIN bus lines are short to power supply, the voltmeter indicates a constant value.
(5) Measure the voltage between the lighting control sensor connector (LIN2 terminal) and the body ground.
  • The voltmeter needle does not swing.
noteIf the LIN bus lines are short to power supply, the voltmeter indicates a constant value.
Is the check result normal?
Go to Step 2.
Repair the connector(s) or wiring harness.
 
STEP 2. Measure the resistance at the LIN bus lines.
Check the LIN bus lines for short to ground.
(1) Disconnect all the connectors leading to the LIN bus lines.
(2) Measure the resistance between the column switch connector (DATA terminal) and the body ground.
  • No continuity (1 kΩ or more)
(3) Measure the resistance between the sunroof motor assembly connector (LIN2 terminal) and the body ground. <Vehicles with sunroof>
  • No continuity (1 kΩ or more)
(4) Measure the resistance between the lighting control sensor connector (LIN2 terminal) and the body ground.
  • No continuity (1 kΩ or more)
Is the check result normal?
Go to Step 3.
Repair the connector(s) or wiring harness.
 
STEP 3. Check the column switch.
Disconnect column switch connector, and recheck whether DTC U1515 is set.
(1) Connect all the relevant ECUs, and disconnect column switch connector only.
(2) Erase the DTC.
(3) Turn the ignition switch from "LOCK" (OFF) to "ON" position.
(4) Check whether DTC U1515 is set.
noteIf DTC U1515 is not set, DTC U1109 is set because the column switch is disconnected. This is normal.
(5) Turn the ignition switch to the "LOCK" (OFF) position.
Is DTC U1515 set?
Reconnect the column switch connector, and go to Step 4.
Replace the column switch (Refer to GROUP 54A - Column switch ).
 
STEP 4. Check the sunroof motor assembly.
Disconnect sunroof motor assembly connector, and recheck whether DTC U1515 is set.
(1) Connect all the relevant ECUs, and disconnect sunroof motor assembly connector only.
(2) Erase the DTC.
(3) Turn the ignition switch from "LOCK" (OFF) to "ON" position.
(4) Check whether DTC U1515 is set.
noteIf DTC U1515 is not set, DTC U0169 is set because the sunroof motor assembly is disconnected. This is normal.
(5) Turn the ignition switch to the "LOCK" (OFF) position.
Is DTC U1515 set?
Reconnect the sunroof motor assembly connector, and go to Step 5.
Replace the sunroof motor assembly (Refer to GROUP 42A - Sunroof Assembly ).
 
STEP 5. Check the lighting control sensor.
Disconnect lighting control sensor connector, and recheck whether DTC U1515 is set.
(1) Connect all the relevant ECUs, and disconnect lighting control sensor connector only.
(2) Erase the DTC.
(3) Turn the ignition switch from "LOCK" (OFF) to "ON" position.
(4) Check whether DTC U1515 is set.
noteIf DTC U1515 is not set, DTC U0231 is set because the lighting control sensor is disconnected. This is normal.
(5) Turn the ignition switch to the "LOCK" (OFF) position.
Is DTC U1515 set?
Reconnect the lighting control sensor, and go to Step 6.
Replace the lighting control sensor (Refer to GROUP 54A - Lighting Control Sensor ).
 
STEP 6. Recheck for DTC.
Check again if the DTC is set in the ETACS-ECU.
(1) Erase the DTC.
(2) Turn the ignition switch from "LOCK" (OFF) to "ON" position.
(3) Check whether DTC U1515 is set.
(4) Turn the ignition switch to the "LOCK" (OFF) position.
Is the DTC set?
Replace the ETACS-ECU (Refer to GROUP 54A - ETACS-ECU ).
The trouble can be an intermittent malfunction (Refer to GROUP 00 - How to Cope with Intermittent Malfunction ).