DTC B1503: Exhaust Heat Management Warning Detected: Procedure

1. Set the vehicle in the maintenance mode using the Techstream. Refer to INSPECTION MODE PROCEDURE .
2. Connect the Techstream to the DLC3.
3. Turn the power switch on (IG).
4. Turn the Techstream on.
5. Enter the following menus: Body Electrical / Combination Meter / Data List.
6. Check the values by referring to the table below.
   COMBINATION METER
   
   

   Tester Display	Measurement Item/Range	Normal Condition	Diagnostic Note
   Coolant Temperature	Engine coolant temperature/-40 to 127.5°C (-40 to 261.5°F)	After warming up: 80 to 100°C (176 to 212°F)	-

   HINT: 

   • The engine coolant temperature value in this inspection is the data sent from the engine coolant temperature sensor for the SFI system.
   • When the Data List values do not match, a signal output error of the ECM is suspected.

   OK

   Engine coolant temperature displayed on the Techstream is 80 to 100°C (176 to 212°F) after warming up

NG → See step   4 

OK: Go to next step 

1. Disconnect the G2 engine coolant temperature sensor connector.
2. Disconnect the L27 combination meter assembly connector.
3. Measure the resistance according to the value(s) in the table below.

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   G2-2 (TWS3) - L27-16 (TWS3)	Always	Below 1 Ω
   G2-1 (E2) - L27-9 (E2)	Always	Below 1 Ω
   G2-2 (TWS3) or L27-16 (TWS3) - Body ground	Always	10 kΩ or higher

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

OK: Go to next step 

1. Remove the engine coolant temperature sensor. Refer to REMOVAL .
   Fig 1: Inspecting Engine Coolant Temperature Sensor

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. Measure the resistance according to the value(s) in the table below.

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   2 (TWS3) - 1 (E2)	Temperature is 20 °C (68°F)	2.32 to 2.59 kΩ
   2 (TWS3) - 1 (E2)	Temperature is 80 °C (176°F)	0.310 to 0.326 kΩ

   TEXT IN ILLUSTRATION
   
   

   *a	Component without harness connected (Engine Coolant Temperature Sensor)
   *b	Resistance kΩ
   *c	Temperature °C (°F)

NG → See step   5 

OK → See step   6