Electrical Test Of Glow Plug - Webasto Thermo Top V Workshop Manual

Thermo Top V

6.3.1.4 Electrical test of glow plug

The cold resistance must be checked using a multimeter
with the 4-conductor measuring principle.
Multimeters without the 4-conductor measuring principle
may not be used for this purpose.
Cold resistance between Contact 1 and 2 (connector X3,
see Fig. 701) at 24 ± 6 °C: 0.200 to 0.300 ohms.
Short-circuit test between Contact 1 or 2 (connector X3, see
Fig. 701) and fan housing =
6.3.1.5 Testing temperature sensor and overheating
sensor
When testing the cold resistance, a distinction must be
made between the variants coolant temperature sensor G1
(NTC) and overheating sensor G2 (PTC). For this purpose,
the contacts of the connector X5 (see Fig. 701) of the sen-
sors are connected to a multimeter and the resistance meas-
ured.
In addition, the short-circuit to earth to the metal housing,
wire crimpings and deformations of the plastic cap of the
sensors must also be checked.
Variant Contacts on
connector X5
G1 Connect Con-
(NTC) tact 2 to 6
G2 (PTC) Connect Con-
tact 3 to 7
Fig. 604 Resistance values of temperature sensor and
overheating sensor
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ohms
min. cold max. cold
resistance resistance
[ohms] [ohms]
at 20 ± 6 °C at 20 ± 6 °C
1998 4050
0 250
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Operating tests
603