DTC U1840[86] Invalid Data Received From BCM (Stop Lamp) (ABS/ESC)

1. Brake control system check

Refer to "54.Brake Control 4A.Troubleshooting(ABS/ESC) diagnostic System Check - Brake Controls".

2. Prioritized DTC check

1) Turn OFF the ignition switch.

2) Connect the scan tool.

3) Turn ON the ignition switch.

4) Observe the BCM DTC information on the scan tool. Is a DTC set?

Yes

Go to the applicable DTC diagnosis.

No

=>Go to Repair verification.

3. Repair verification

1) Clear the DTC with a scan tool.

2) Turn OFF the ignition switch.

3) Start the engine.

4) Observe the DTC information with a scan tool.