Introduction:
Some 2010 Prius vehicles may exhibit a Master Warning Light (MWL) “ON” condition with DTC P0A2D/249, Drive Motor “A” Temperature Sensor Open Circuit, detected. This condition may be caused by water exposure to the engine relay block if the relay block cover is not properly installed.
Repair Procedure:
1. Remove the engine bay relay block cover and inspect it for signs of water intrusion or contamination inside.
• If water intrusion or contamination is present, proceed to step 2.
• If no water intrusion or contamination is present, proceed to step 3.
2. If any fuses or relays show any signs of corrosion, repair or replace as necessary.
3. Disconnect and inspect connector DA1 at the relay block for signs of water intrusion or contamination.
• If water intrusion or contamination is found, clean and dry as needed, then proceed to step 4.
• If no water intrusion or contamination is found, proceed to step 4.
4. Reinstall the relay block cover and ensure it is properly secured.
• Secure the rear hooks of the relay block cover.
• Secure the front hook of the relay block cover.
5. Clear all DTCs and retest. If P0A2D/249 recurs, follow the repair manual diagnostic procedure.
Courtesy of ALLDATA
