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Auxiliary Heating - Electric Booster Heater Mondeo 2001 (10/2000-02/2007)
Diagnosis and Testing

Refer to Wiring Diagrams Section 412-02B, for schematic and connector information.

Special Tool(s)

Terminal Probe Kit

418-S035

General Equipment
Digital Multimeter
Clip-on Ammeter (DC)
Worldwide Diagnostic System (WDS)

Inspection and Checking

  1. VERIFY customer concern.
  1. Visually CHECK for any obvious mechanical or electrical damage.

Visual Inspection

Mechanical Electrical
  • Coolant level
  • Electric engine coolant heater mounting
  • Fuses
  • Wiring harness
  • Connectors
  1. RECTIFY any obvious causes for a concern found during the visual inspection before performing any further tests. CHECK the operation of the system.
  1. If the concern persists, PERFORM a fault diagnosis on the electronic engine management (PCM) with WDS and RECTIFY any displayed faults in accordance with the displayed fault description. CHECK the operation of the system.
  1. For vehicles with no stored faults, PROCEED in accordance with the Symptom Chart according to the fault symptom.
  1. Following checking or elimination of the fault and after completion of operations, the fault memories of all vehicle modules must be READ OUT and any stored faults must be DELETED. READ OUT all fault memories again following a road test.

Symptom Chart

Symptom Chart

Symptom Possible Sources Action
Electric engine coolant heater inoperative / partly inoperative
*
Fuse(s)
*
Circuit(s)
*
Intake air temperature signal
*
Relay 1, electric engine coolant heater
*
Relay 2, electric engine coolant heater
*
Electric engine coolant heater
*
Powertrain control module (PCM)
*
GO to Pinpoint Test A.

System Check

PINPOINT TEST A : ELECTRIC ENGINE COOLANT HEATER INOPERATIVE / PARTLY INOPERATIVE

TEST CONDITIONS DETAILS/RESULTS/ACTIONS
A1: CHECK THE ELECTRIC ENGINE COOLANT HEATER
NOTE:
NOTE:The electric engine coolant heater only works when the ambient temperature is below 5°C, the coolant temperature does not exceed 71°C and sufficient generator capacity is available.
1
Allow the engine to run.

2
Measure the current in circuits 15S-RH24 (GN/OG), 15S-RH26A (GN/WH) and 15S-RH26B (GN/WH) at the electric engine coolant heater using the clip-on ammeter.

Is a current measured?
Yes
No
A2: CHECK 1ST STAGE OF ELECTRIC ENGINE COOLANT HEATER CIRCUIT

1
Measure the current in circuit 15S-RH24 (GN/OG) at the electric engine coolant heater using the clip-on ammeter.

Is a current of more than 10 A measured?
Yes
No
A3: CHECK FUSE F3
1
Ignition switch in position 0.
2
CHECK fuse F3 (BJB).

Is the fuse OK?
Yes
No
RENEW fuse F3 (60 A). If the fuse blows again, LOCATE and REPAIR the short to ground using the Wiring Diagrams. CHECK the operation of the system.
A4: CHECK THE VOLTAGE AT FUSE F3
1
Connect fuse F3 (BJB).
2
Measure the voltage between fuse F3 (60 A) and ground.

Does the meter display battery voltage?
Yes
No
REPAIR the voltage supply to fuse F3 using the Wiring Diagrams. CHECK the operation of the system.
A5: CHECK FUSE F82
1
CHECK fuse F82 (CJB).

Is the fuse OK?
Yes
No
RENEW fuse F82 (7.5 A). If the fuse blows again, LOCATE and REPAIR the short to ground using the Wiring Diagrams. CHECK the operation of the system.
A6: CHECK THE VOLTAGE AT FUSE F82
1
Connect fuse F82 (CJB).
2
Ignition switch in position II.
3
Measure the voltage between fuse F82 (7.5 A) and ground.

Does the meter display battery voltage?
Yes
No
REPAIR the voltage supply to fuse F82 using the Wiring Diagrams. CHECK the operation of the system.
A7: CHECK VOLTAGE AT RELAY 1, ELECTRIC ENGINE COOLANT HEATER
1
Ignition switch in position 0.
2
Disconnect relay 1, electric engine coolant heater from socket C125.

3
Measure the voltage between relay 1, electric engine coolant heater, connector C125, pin 3, circuit 30-RH24A (RD), wiring harness side and ground.

Does the meter display battery voltage?
Yes
No
LOCATE and REPAIR the break in the circuit between fuse F3 and soldered connection S361 using the Wiring Diagrams. CHECK the operation of the system.
A8: CHECK CONTROL VOLTAGE AT RELAY 1, ELECTRIC ENGINE COOLANT HEATER
1
Ignition switch in position II.

2
Measure the voltage between relay 1, electric engine coolant heater, connector C125, pin 1, circuit 15-RH23 (GN/RD), wiring harness side and ground.

Does the meter display battery voltage?
Yes
No
LOCATE and REPAIR break in circuit between relay 1, electric engine coolant heater or relay 2, electric engine coolant heater and fuse F82 using the Wiring Diagrams. CHECK the operation of the system.
A9: CHECK THE GROUND CONNECTION OF THE ENGINE COOLANT HEATER
1
Ignition switch in position 0.

2
Measure the resistance between relay 1, electric engine coolant heater, connector C125, pin 5, circuit 15S-RH24 (GN/OG) and ground.

Is a resistance of less than 1.2 Ohm registered?
Yes
No
A10: CHECK THE ELECTRIC ENGINE COOLANT HEATER GLOW PLUG

1
Measure the resistance between electric engine coolant heater, connector C123, pin 1, circuit 15S-RH24 (GN/OG), component side and electric engine coolant heater housing.

Is a resistance of less than 1.2 Ohm registered?
Yes
CHECK the ground connection of the electric engine coolant heater, if necessary CLEAN the threaded connection(s) on the bulkhead. CHECK the operation of the system.
No
RENEW the electric engine coolant heater. CHECK the operation of the system.
A11: CHECK THE SIGNAL FROM THE INTAKE AIR TEMPERATURE SENSOR
NOTE:
NOTE:The intake air temperature sensor is integrated in the mass air flow sensor (MAF, engine management).
1
Connect the diagnostic tool.
2
Check the intake air temperature signal using the diagnostic unit.

Is the intake air temperature signal OK, i.e. is the indicated temperature value plausible?
Yes
Check the powertrain control module (PCM) and RENEW as necessary. CHECK the operation of the system.
No
A12: CHECK VOLTAGE AT RELAY 1, ELECTRIC ENGINE COOLANT HEATER
1
Ignition switch in position 0.
2
Disconnect relay 1, electric engine coolant heater from socket C125.

3
Measure the voltage between relay 1, electric engine coolant heater, connector C125, pin 3, circuit 30-RH24A (RD), wiring harness side and ground.

Does the meter display battery voltage?
Yes
No
LOCATE and RECTIFY the break in circuit 30-RH24A (RD) between relay 1, electric engine coolant heater and solder point S361 using the Wiring Diagrams. CHECK the operation of the system.
A13: CHECK CONTROL VOLTAGE AT RELAY 1, ELECTRIC ENGINE COOLANT HEATER
1
Ignition switch in position II.

2
Measure the voltage between relay 1, electric engine coolant heater, connector C125, pin 1, circuit 15-RH23 (GN/RD), wiring harness side and ground.

Does the meter display battery voltage?
Yes
No
LOCATE and RECTIFY the break in circuit 15-RH23 (GN/RD) between relay 1, electric engine coolant heater and fuse F82 using the Wiring Diagrams. CHECK the operation of the system.
A14: CHECK THE CIRCUIT BETWEEN RELAY 1, ELECTRIC ENGINE COOLANT HEATER AND THE ELECTRIC ENGINE COOLANT HEATER FOR OPEN CIRCUIT.
1
Ignition switch in position 0.

2
Measure the resistance between relay 1, electric engine coolant heater, socket C125, pin 5, circuit 15S-RH24 (GN/OG), wiring harness side and ground.

Is a resistance of less than 1.2 Ohm registered?
Yes
No
A15: CHECK THE ELECTRIC ENGINE COOLANT HEATER
1
Disconnect connector C124.

2
Measure the resistance between connector C124, pin 1, circuit 15S-RH24 (GN/OG), component side and ground.

Is a resistance of less than 1.2 Ohm registered?
Yes
LOCATE and RECTIFY the break in circuit 15S-RH24 (GN/OG) between relay 1, electric engine coolant heater and the electric engine coolant heater using the Wiring Diagrams. CHECK the operation of the system.
No
RENEW the electric engine coolant heater. CHECK the operation of the system.
A16: CHECK RELAY 1, ELECTRIC ENGINE COOLANT HEATER
1
Check relay 1, electric engine coolant heater in accordance with the component test at the end of this section.

Is relay 1, electric engine coolant heater OK?
Yes
- All except vehicles with common rail injection system and integrated injector module (IDM):GO to A17.
- Vehicles with common rail injection system and integrated IDM:GO to A18.
No
RENEW relay 1, electric engine coolant heater. CHECK the operation of the system.
A17: CHECK FOR BREAK IN CIRCUIT BETWEEN THE PCM AND RELAY 1, ELECTRIC ENGINE COOLANT HEATER - ALL EXCEPT VEHICLES WITH COMMON RAIL INJECTION SYSTEM AND INTEGRATED IDM
1
Disconnect connector C100 from PCM.

2
Measure resistance between relay 1, electric engine coolant heater, socket C125, pin 2, circuit 91S-RH23 (BK/OG), wiring harness side and PCM, connector C100, pin 98, circuit 91S-RH23 (BK/OG), wiring harness side.

Is a resistance of less than 2 Ohm registered?
Yes
CHECK the PCM and RENEW if necessary. CHECK the operation of the system.
No
LOCATE and RECTIFY the break in circuit 91S-RH23 (BK/OG) between PCM and relay 1, electric engine coolant heater using the Wiring Diagrams. CHECK the operation of the system.
A18: CHECK FOR BREAK IN CIRCUIT BETWEEN THE PCM AND RELAY 1, ELECTRIC ENGINE COOLANT HEATER - VEHICLES WITH COMMON RAIL INJECTION SYSTEM AND INTEGRATED IDM
1
Disconnect connector C200 from PCM.

2
Measure resistance between relay 1, electric engine coolant heater, socket C125, pin 2, circuit 91S-RH23 (BK/OG), wiring harness side and PCM, connector C200, pin 61, circuit 91S-RH23 (BK/OG), wiring harness side.

Is a resistance of less than 2 Ohm registered?
Yes
CHECK the PCM and RENEW if necessary. CHECK the operation of the system.
No
LOCATE and RECTIFY the break in circuit 91S-RH23 (BK/OG) between PCM and relay 1, electric engine coolant heater using the Wiring Diagrams. CHECK the operation of the system.
A19: CHECK VOLTAGE AT RELAY 2, ELECTRIC ENGINE COOLANT HEATER
1
Ignition switch in position 0.
2
Disconnect relay 2, electric engine coolant heater from socket C126.

3
Measure the voltage between relay 2, electric engine coolant heater, connector C126, pin 3, circuit 30-RH26 (RD), wiring harness side and ground.

Does the meter display battery voltage?
Yes
No
LOCATE and RECTIFY the break in circuit 30-RH26 (RD) between relay 2, electric engine coolant heater and solder point S361 using the Wiring Diagrams. CHECK the operation of the system.
A20: CHECK CONTROL VOLTAGE AT RELAY 2, ELECTRIC ENGINE COOLANT HEATER
1
Ignition switch in position II.

2
Measure the voltage between relay 2, electric engine coolant heater, connector C126, pin 1, circuit 15-RH25 (GN/BK), wiring harness side and ground.

Does the meter display battery voltage?
Yes
No
LOCATE and RECTIFY the break in circuit 15-RH25 (GN/BK) between relay 2, electric engine coolant heater and fuse F82 using the Wiring Diagrams. CHECK the operation of the system.
A21: CHECK THE CIRCUIT BETWEEN RELAY 2, ELECTRIC ENGINE COOLANT HEATER AND THE ELECTRIC ENGINE COOLANT HEATER FOR OPEN CIRCUIT.
1
Ignition switch in position 0.

2
Measure the resistance between relay 2, electric engine coolant heater, connector C126, pin 5, circuit 15S-RH26 (GN/WH), wiring harness side and ground.

Is a resistance of less than 0.7 Ohm registered?
Yes
No
A22: CHECK THE ELECTRIC ENGINE COOLANT HEATER
1
Disconnect connector C124.

2
Measure the resistance between connector C124, pin 3, circuit 15S-RH26B (GN/WH), component side and ground.

Is a resistance of less than 1.2 Ohm registered?
Yes
No
RENEW the electric engine coolant heater. CHECK the operation of the system.
A23: CHECK THE ELECTRIC ENGINE COOLANT HEATER

1
Measure the resistance between connector C124, pin 5, circuit 15S-RH26A (GN/WH), component side and ground.

Is a resistance of less than 1.2 Ohm registered?
Yes
LOCATE and RECTIFY the break in circuit 15S-RH26 (GN/WH), 15S-RH26A (GN/WH) or 15S-RH26B (GN/WH) between relay 2, electric engine coolant heater and the electric engine coolant heater using the Wiring Diagrams. CHECK the operation of the system.
No
RENEW the electric engine coolant heater. CHECK the operation of the system.
A24: CHECK RELAY 2, ELECTRIC ENGINE COOLANT HEATER
1
Check relay 2, electric engine coolant heater in accordance with the component test at the end of this section.

Is relay 2, electric engine coolant heater OK?
Yes
- All except vehicles with common rail injection system and integrated injector module (IDM):GO to A25.
- Vehicles with common rail injection system and integrated IDM:GO to A26.
No
RENEW relay 2, electric engine coolant heater. CHECK the operation of the system.
A25: CHECK FOR BREAK IN CIRCUIT BETWEEN THE PCM AND RELAY 2, ELECTRIC ENGINE COOLANT HEATER - ALL EXCEPT VEHICLES WITH COMMON RAIL INJECTION SYSTEM AND INTEGRATED IDM
1
Disconnect connector C100 from PCM.

2
Measure resistance between relay 2, electric engine coolant heater, socket C126, pin 2, circuit 91S-RH25 (BK/GN), wiring harness side and PCM, connector C100, pin 75, circuit 91S-RH25 (BK/GN), wiring harness side.

Is a resistance of less than 2 Ohm registered?
Yes
CHECK the PCM and RENEW if necessary. CHECK the operation of the system.
No
LOCATE and RECTIFY the break in circuit 91S-RH25 (BK/GN) between PCM and relay 2, electric engine coolant heater using the Wiring Diagrams. CHECK the operation of the system.
A26: CHECK FOR BREAK IN CIRCUIT BETWEEN THE PCM AND RELAY 2, ELECTRIC ENGINE COOLANT HEATER - VEHICLES WITH COMMON RAIL INJECTION SYSTEM AND INTEGRATED IDM
1
Disconnect connector C200 from PCM.

2
Measure resistance between relay 2, electric engine coolant heater, socket C126, pin 2, circuit 91S-RH25 (BK/GN), wiring harness side and PCM, connector C200, pin 62, circuit 91S-RH25 (BK/GN), wiring harness side.

Is a resistance of less than 2 Ohm registered?
Yes
CHECK the PCM and RENEW if necessary. CHECK the operation of the system.
No
LOCATE and RECTIFY the break in circuit 91S-RH25 (BK/GN) between PCM and relay 2, electric engine coolant heater using the Wiring Diagrams. CHECK the operation of the system.

Component Tests

Relay, electric engine coolant heater

  1. Check the normally open contact in the unswitched state:
    • Measure the resistance at the relay, between pin 3 and pin 5, component side.
    • Is a resistance of more than 10,000 Ohms measured? If yes, go to 2. If no, RENEW the relay.

  1. Check the normally open contact in the switched state:
    • Using a fused test cable (1 A), connect pin 1 of the relay, component side, to the battery positive terminal.
    • Using a test cable, connect pin 2 of the relay, component side, to the battery negative terminal.
    • Measure the resistance at the relay, between pin 3 and pin 5, component side.
    • Is a resistance of less than 2 Ohms registered? If yes, then the relay is OK. If no, RENEW the relay.

Mechanical Repairs > 4 Electrical > 412 Climate Control System > 412-02B Auxiliary Heating > Description and Operation > Diagnosis and Testing > Electric Booster Heater

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