Ford Galaxy / Ford S-MAX. Manual — part 334

The IAT sensor output is useful if the engine being tested is cold or after an over-night cold
soak. The ECT sensor or CHT sensor and the IAT sensor should either indicate the same
value or be within 1 to 2 degrees Celsius of each other.

The ECT sensor output is important to display as it indicates the engine warm-up and
opening temperature for the thermostat. It will initially indicate a slightly higher reading
just before the thermostat opens and then drops back before settling to a near flat line
output (see graphic below).

Description

Thermostat opens

Thermostat settles into a cyclic open and closure pattern

CAUTION: If the ECT sensor output reaches the 120ºC default line under normal

cooling system pressure, internal damage may be caused to the engine and a diagnostic
trouble code (DTC) will be set in the PCM. The test should be stopped and the cause
located and corrected. If the cooling system does not pressurize, the coolant will boil at
100ºC which may also damage the engine. CARRY OUT the Coolant Expansion Tank Cap
Pressure Test Component Test in this section.

If the Ford approved diagnostic tool only allows the ECT sensor to be displayed in volts,
refer to the following table for corresponding Celsius values:

The CHT sensor output is useful to examine the cylinder head temperature rise during the
warm-up cycle and later during the normal light throttle cruise test. This sensor output may
vary between vehicles with manual transmission and vehicles with automatic transmission
and should be used for reference only.

The LOAD display is used for reference as it is necessary to maintain a stable load line
during the test. It is necessary to carry out the test under normal light throttle cruise
driving conditions and average loads, typically 40% to 70% of the load value.

The VSS output is used for reference but can help to identify misfires and sensors which fail
during the warm-up cycle.

The RPM display indicates the engine speed and can be compared with the DSRPM.

The DSRPM is the desired or calculated idle speed which the PCM commands the engine to
reach. If the thermostat opens too early (before the correct opening temperature has been
reached), the engine will not reach this value.

When using the Ford approved diagnostic tool in datalogger mode, the signals recorded

Item

A

B

Volts

ºCelsius

1.33

60

1.02

70

0.78

80

0.60

90

0.46

100

0.35

110

0.27

120

Part Number

-

-

should remain within the DEFAULT values set by the Ford approved diagnostic tool.

3.

WARNING: Make sure that the Ford approved diagnostic tool is placed in the

vehicle so that it does not interfere with the safe operation of the vehicle. Do not
place the Ford approved diagnostic tool in the deployment path of any air bag.
Failure to follow these instructions may result in personal injury.
NOTE: The road test is best carried out with the aid of another technician in the
vehicle to enable the vehicle to be driven safely while the sensor outputs are
monitored within datalogger. If there is only one technician available, the Ford
approved diagnostic tool can be set up (using the record/capture mode camera
icon) before leaving the workshop to record a 16 km (10 mile) test.
NOTE: The results from the test are more conclusive if the engine is cold when the
test is started.

3. Carry out a road test.

REFER to: Road/Roller Testing (100-00 General Information, Description and
Operation).

4. 4. Drive the vehicle at a constant throttle opening and set speed until the ECT value

settles into a shallow rise and fall signal, close to a straight line. This indicates that
the thermostat is functioning correctly.

NOTE: Some thermostats indicate the temperature(s) in Celsius and Fahrenheit.

The graphic below shows the location and an example of the opening temperature (88ºC)
and fully open temperature (102ºC) of a thermostat.

The graphic below shows an alternative method used to show the opening temperature
(88ºC) and fully open temperature (112ºC) of a thermostat.

Description

Opening temperature

Fully open temperature

NOTE: Generally, most thermostats maintain a coolant temperature between 88ºC
(190ºF) and 92ºC (198ºF) although dual stage electric thermostats may increase the
coolant temperature up to 100ºC (212ºF) under light engine load conditions.

The engine should start cleanly and the ECT value will rise quite quickly with smooth
progression. If the ECT signal appears unstable or erratic, the ECT sensor, electrical

Item

A

B

Part Number

-

-

connector and wiring harness to the PCM need to be visually inspected for damage, chafing
or water ingress.

The temperature should rise to approximately 90ºC for a thermostat that has an 88ºC
value. The signal value will then fall as cooler coolant enters the engine.

If the ECT value fails to maintain a constant value and falls back to lower figures, typically
between 60ºC (140ºF) and 70ºC (150ºF), the thermostat and its sealing function within the
thermostat housing must be checked.

5. 5. INSTALL a new thermostat housing and thermostat housing gasket as necessary.

REFER to:

Thermostat Housing

(303-03C Engine Cooling - 2.5L Duratec

(162kW/220PS) - VI5, Removal and Installation).

6. 6. Carry out another road test from step 1 using the same criteria to confirm that the

concern has been rectified.

7. 7. Using the Ford approved diagnostic tool, clear the PCM keep alive memory (KAM)

or electrically erasable programmable read only memory (EEPROM) so that new
drive values can be learnt.

Engine Cooling - 2.5L Duratec
(162kW/220PS) - VI5 - Cooling System
Draining, Filling and Bleeding

S-MAX/Galaxy 2006.5 (02/2006-)

Print

General Procedures

NOTE: When releasing the cooling system pressure, cover the coolant expansion tank cap
with a thick cloth.

CAUTION: The fluid level must remain between the MAX and MIN marks.

1. Release the cooling system pressure by slowly

turning the coolant expansion tank cap between
2 and 3 turns.

2.

3. Raise and support the vehicle.

Refer to: Lifting (100-02, Description and
Operation).

4.

5.

6. Install the radiator drain plug.

7. Lower the vehicle.

8. Switch the interior heater blower off.

9. Remove the right-hand front headlamp.

Refer to: Headlamp Assembly (417-01, Removal
and Installation).

10.