54B-CODE NO. U1515 BUS ERROR (LIN)

DTC U1515 No bus activity error for LIN

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 GROUP 54A, Immobilizer System - How to Register Key ID .)

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.

TROUBLESHOOTING HINTS

The ETACS-ECU may be defective.
The slave ECU may be defective.
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 ground.

The voltmeter needle does not swing.

note	If 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 ground. <Vehicles with sunroof>

The voltmeter needle does not swing.

note	If 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 ground. <Vehicles with lighting control sensor>

The voltmeter needle does not swing.

note	If the LIN bus lines are short to power supply, the voltmeter indicates a constant value.

(6) Measure the voltage between the power window main switch connector (LIN terminal) and ground.

The voltmeter needle does not swing.

note	If 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 ground.

No continuity (1 kΩ or more)

(3) Measure the resistance between the sunroof motor assembly connector (LIN2 terminal) and ground. <Vehicles with sunroof>

No continuity (1 kΩ or more)

(4) Measure the resistance between the lighting control sensor connector (LIN2 terminal) and ground. <Vehicles with lighting control sensor>

No continuity (1 kΩ or more)

(5) Measure the resistance between the power window main switch connector (LIN terminal) and 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)

caution

To 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 the Scan Tool (M.U.T.-III)

(2) Erase the DTC.

(3) Turn the ignition switch from "LOCK" (OFF) to "ON" position.

(4) Check whether DTC U1515 is set.

note	If DTC 1515 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 lighting switch.

STEP 4. Check the sunroof motor assembly.

Disconnect sunroof motor assembly connector, and recheck whether DTC U1515 is set.

(1)

caution

To 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 the Scan Tool (M.U.T.-III)

(2) Erase the DTC.

(3) Turn the ignition switch from "LOCK" (OFF) to "ON" position.

(4) Check whether DTC U1515 is set.

note	If 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.

STEP 5. Check the lighting control sensor.

Disconnect lighting control sensor connector, and recheck whether DTC U1515 is set.

(1)

caution

To 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 the Scan Tool (M.U.T.-III)

(2) Erase the DTC.

(3) Turn the ignition switch from "LOCK" (OFF) to "ON" position.

(4) Check whether DTC U1515 is set.

note	If 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.

STEP 6. Check the power window main switch.

Disconnect power window main switch connector, and recheck whether DTC U1515 is set.

(1)

caution

To 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 the Scan Tool (M.U.T.-III)

(2) Erase the DTC.

(3) Turn the ignition switch from "LOCK" (OFF) to "ON" position.

(4) Check whether DTC U1515 is set.

note	If DTC U1515 is not set, DTC U0215 is set because the power window main switch is disconnected. This is normal.

(5) Turn the ignition switch to the "LOCK" (OFF) position.

Is DTC U1515 set?

Reconnect the power window main switch, and go to Step 7

Replace the power window main switch.

STEP 7. Recheck for diagnostic trouble code.

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.

The trouble can be an intermittent malfunction (Refer to GROUP 00 - How to Cope with Intermittent Malfunction