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7 | Function checks
Testing the heater cartridge when removed
A
B
Fig. 22 Testing the heater cartridge
A Pin 1
Follow these steps:
1.
Connect supply voltage (12 V or 24 V) to PIN1 and PIN2 of
connector.
2.
Measure current
3.
Evaluation:
10.8A
+/- 10 %
5.4A
+/- 10 %
7.11
Check coolant pump
Check control unit
yes
connector. Dam-
aged?
no
Check connector /
yes
cable for coolant
pump. Damaged?
no
Check direction of
no
flow. Correct?
yes
Component is
OK.
28 / 49
B Pin 2
12 V
24 V
Replace com-
ponent.
Replace com-
ponent.
X: Outlet
Y: Inlet
Correct if ne-
cessary, see
illustration on
right and the
installation
instructions.
7.12
Checking coolant temperature
sensors
7.12.1
Testing the coolant temperature sensors
via WTT Diagnostics
Fig. 23 Coolant temperature sensors testing via WTT
A
WTT USB interface
Follow these steps:
1.
Connect WTT
2.
Start WTT
3.
Evaluation:
– The temperature values displayed in the WTT must be
plausible.
7.12.2
Testing resistance of coolant temperature
sensors via WTT
Test of coolant temperature sensors when installed on the
heater by testing the electrical resistance. See chapter 10.6,
D
"Wiring diagrams " on page 40.
A
C
Evaluation:
F
l Coolant temperature sensor contacts on connector X3 pin
1 and 2
l Overheating sensor contacts on connector X3 pin 5 and 6
l Checking the cold resistance at 20°C: R = 3.266 - 3.479
ohms
7.13
Checking ignition electrode
7.13.1
Testing the ignition electrode via WTT
Diagnostics
Follow these steps:
X
1.
Connect WTT
2.
Start WTT
3.
Activate component test for ignition spark generator (max-
Y
imum duration of 10 s, process can be repeated).
B
Diagnostic adapter
9039412C Workshop manual TTP 120 _ 150
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