Pinpoint tests of additional heating

A1: CHECKING FUSE F23

1Enter the OFF position.

2CHECK Fuse F23 (BJB).

• Is the fuse good?

→ Yes

Go to A2

→ No

REPLACE fuse F23 (20A). CHECK the system for proper operation. If the fuse blows again, LOCATE and REPAIR the short to ground using the wiring diagrams.

A2: CHECKING THE VOLTAGE AT FUSE F23

1Connect Fuse F23 (BJB).

2Measure the voltage between fuse F23 (20 A) and ground.

• Is battery voltage registered?

→ Yes

Go to A3

→ No

RESTORE power to fuse F23 using the wiring diagrams. CHECK that the system is operating correctly.

A3: CHECKING FUSE F28

1CHECK Fuse F28 (BJB).

• Is the fuse good?

→ Yes

Go to A4

→ No

REPLACE fuse F28 (10A). CHECK the system for proper operation. If the fuse blows again, LOCATE and REPAIR the short to ground using the wiring diagrams.

A4: CHECKING THE VOLTAGE AT FUSE F28

1Connect Fuse F28 (BJB).

2Enter the ON position.

3Measure the voltage between fuse F28 (10 A) and ground.

• Is battery voltage registered?

→ Yes

Go to A5

→ No

RESTORE power to fuse F28 using the wiring diagrams. CHECK that the system is operating correctly.

A5: CHECKING THE VOLTAGE IN THE ADDITIONAL HEATER

1Enter the OFF position.

2Disconnect C878 auxiliary heater.

3Measure the voltage between pin 1 of the auxiliary heater connector C878, circuit 30-RD18 (red), wiring harness side, and ground.

• Is battery voltage registered?

→ Yes

Go to A6

→ No

LOCATE and REPAIR the open in the electrical circuit between the booster heater and fuse F23 using the wiring diagrams. CHECK the system for proper operation.

A6: CHECKING THE VOLTAGE IN THE ADDITIONAL HEATER

1Enter the ON position.

2Measure the voltage between pin 4 of the auxiliary heater connector C878, circuit 15-RD18 (green/red), wiring harness side, and ground.

• Is battery voltage registered?

→ Yes

Go to A7

→ No

LOCATE and REPAIR the open in the electrical circuit between the booster heater and solder joint S117 using the wiring diagrams. CHECK the system for proper operation.

A7: CHECKING CONTROL VOLTAGE IN THE ADDITIONAL HEATER

NOTE:Use suitable methods to cool the outside temperature sensor to at least 5°C.

1Enter the START position.

2Measure the voltage between pin 5 of the auxiliary heater connector C878, circuit 64S-RD18 (blue/white), wiring harness side, and ground.

• Is battery voltage registered?

→ Yes

Go to A8

→ No

Go to A9

A8: CHECKING THE ADDITIONAL HEATER GROUND CIRCUIT

1Enter the OFF position.

2Measure the resistance between pin 2 of auxiliary heater connector C878, circuit 31-RD18 (black), wiring harness side, and ground.

• Resistance less than 2 ohms?

→ Yes

CHECK and if necessary REPLACE the auxiliary heater. CHECK that the system is operating correctly.

→ No

LOCATE and REPAIR the open in the electrical circuit between the booster heater and ground point G37 using the wiring diagrams. CHECK the system for proper operation.

A9: CHECKING THE VOLTAGE IN THE OUTDOOR TEMPERATURE SENSOR

1Enter the OFF position.

2Disconnect the outside temperature sensor C875.

3Enter the START position.

4Measure the voltage between pin 1 of the outside temperature sensor connector C875, circuit 64-RD18 (blue/white), wiring harness side, and ground.

• Is battery voltage registered?

→ Yes

Go to A10

→ No

Go to A11

A10: CHECKING THE ELECTRICAL CIRCUIT BETWEEN THE OUTSIDE TEMPERATURE SENSOR AND THE BOOSTER HEATER FOR OPEN CIRCUIT

1Enter the OFF position.

2Measure the resistance between pin 2 of the outside temperature sensor connector C875, circuit 64S-RD18 (blue/white), wiring harness side, and pin 5 of the auxiliary heater connector 878, circuit 64S-RD18 (blue/white), wiring harness side.

• Resistance less than 2 ohms?

→ Yes

REPLACE the outside temperature sensor. CHECK the system for proper operation.

→ No

LOCATE and REPAIR the open in the 64S-RD18 (Blue/White) circuit between the outside temperature sensor and the booster heater using the wiring diagrams. CHECK for proper system operation.

A11: CHECKING THE VOLTAGE IN THE ENGINE RUN RELAY

1Enter the OFF position.

2Disconnect C1013 Engine Run Relay (BJB).

3Enter the ON position.

4Measure the voltage between pin 3 of the engine run relay connector C1013, circuit 15-PA20 (green/orange), wiring harness side, and ground.

• Is battery voltage registered?

→ Yes

Go to A12

→ No

LOCATE and REPAIR the open in the 15-PA20 (Green/Orange) circuit between the Engine Run Relay and Fuse F28 using the Wiring Diagrams. CHECK for proper system operation.

A12: CHECKING CONTROL VOLTAGE IN ENGINE RUN RELAY

1Measure the voltage between pin 1 of the engine run relay connector C1013, circuit 15-PA19 (BK/GN), wiring harness side, and ground.

• Is battery voltage registered?

→ Yes

Go to A13

→ No

LOCATE and REPAIR the open in the electrical circuit between the engine run relay and solder joint S117 using the wiring diagrams. CHECK the system for proper operation.

A13: CHECKING THE ENGINE RUN RELAY GROUND CIRCUIT

CAUTION: When performing the following test, it is necessary to use a test lamp with a rated voltage of 12 V and a rated power of 1.2 W. Otherwise, the PCM may be damaged or the test may give incorrect results.

NOTE:Before performing the next measurement, make sure the generator is working properly.

1Enter the START position.

2To check the voltage between pins 1 and 2 of the engine run relay connector C1013, use a test lamp (12 V, 1.2 W).

• Is the indicator light on?

→ Yes

Go to A14

→ No

Vehicles with 104-pin EEC: Go to A15

Vehicles with 121-pin EEC: Go to A16

A14: CHECKING THE ELECTRICAL CIRCUIT BETWEEN THE ENGINE RUN RELAY AND THE OUTSIDE TEMPERATURE SENSOR FOR AN OPEN CIRCUIT

1Enter the OFF position.

2Measure the resistance between pin 1 of engine run relay connector C1013, circuit 64-PA20 (YE/BU), harness side and pin 1 of outside temperature sensor connector C875, circuit 64-RD18 (WH/BU), harness side.

• Resistance less than 2 ohms?

→ Yes

REPLACE the engine run relay. CHECK the system for proper operation.

→ No

LOCATE and REPAIR the open in the electrical circuit between the engine run relay and the outside temperature sensor using the wiring diagrams. CHECK the correct operation of the system.

A15: CHECK FOR OPEN WIRE BETWEEN ENGINE RUN RELAY AND POWERTRAIN CONTROL MODULE (PCM)

1Enter the OFF position.

2Disconnect C415 PCM.

3Measure the resistance between engine run relay connector C1013 pin 2, harness side and PCM connector C415 pin 6, circuit 31S-PA19 (GRN/BK), harness side.

• Resistance less than 2 ohms?

→ Yes

CHECK and REPLACE the PCM if necessary. CHECK the system is operating correctly.

→ No

LOCATE and REPAIR the open in the circuit between the engine run relay and the PCM using the wiring diagrams. CHECK the system for proper operation.

A16: CHECK FOR OPEN CIRCUIT BETWEEN ENGINE RUN RELAY AND POWERTRAIN CONTROL MODULE (PCM)

1Enter the OFF position.

2Disconnect C414 PCM.

3Measure the resistance between engine run relay connector C1013 pin 2, harness side and PCM connector C414 pin 23, circuit 31S-PA19 (BK/GN), harness side.

• Resistance less than 2 ohms?

→ Yes

CHECK and REPLACE the PCM if necessary. CHECK the system is operating correctly.

→ No

LOCATE and REPAIR the open in the circuit between the engine run relay and the PCM using the wiring diagrams. CHECK the system for proper operation.