Tennant EC-H2O T12, Service Information Manual, Page: 172 / 178

5-40
T12 Service Information 9009917 (12-12)
SERVICE
TESTING ec-H2O PRESSURE SWITCH
ECP001
Common
Normally
Open
Normally
Closed
1 . key off . disconnect the pressure switch from the
wire harness and remove the switch from the
machine .
2 . Test the resistance of the switch using an ohmmeter
between the common and normally closed terminals .
There should be 0-1 ohms resistance . replace the
switch if the n .C . contacts are open .
ECP003
W U V
Ω
W
U V
Ω
W U V
Ω
1.
2.
3.
3.
U
V
CHASSIS
W
+ - + - + - + - + - + -
6 Volt 6 Volt 6 Volt 6 Volt 6 Volt 6 Volt
Normally
Open
3 . Test the resistance of the switch using an ohmmeter
between the common and normally open terminals .
The switch should test as “o .L .” or open . replace the
switch if the n .o . contacts are shorted .
ECP004
W
U V
Ω
W U V
Ω
W
U V
Ω
1.
2.
3.
3.
U
V
CHASSIS
W
+ - + - + - + - + - + -
6 Volt 6 Volt 6 Volt 6 Volt 6 Volt 6 Volt
Normally
Open
4 . use a bicycle pump with pressure gauge to apply
pressure to the switch as shown below . The
normally open contacts should close at 25 +/-
2 psi (1 .7 bar), increasing pressure . replace the switch
if it does not open correctly .
ECP005
W U V
Ω
W U V
Ω
W
U V
Ω
1.
2.
3.
3.
U
V
CHASSIS
W
+ - + - + - + - + - + -
6 Volt 6 Volt 6 Volt 6 Volt 6 Volt 6 Volt
Normally
Open
3/8” I.D. Tube
0
5
10
15
20
25 30 35
40
45
50
55
60
PSI
for Safety: before leaving or servicing machine, stop
on level surface, turn off machine and remove key .
for Safety: When servicing machine, disconnect bat-
tery connection before working on machine .