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Oil Pressure Switch (GM 3000)
The switch is located on the left side of the engine block
above the oil filter. It is a normally closed switch when the
engine is not running and opens with increasing oil pres-
sure.
Testing with the Engine Off
1. Turn the ignition switch to ON. The oil pressure lamp
should be on.
2. If the lamp does not come on in step 1 above no, dis-
connect the gray wire from the switch and ground it to
the engine block.
A. If the lamp comes on the switch is bad.
B. If the lamp does not come on in step 2, check the
indicating circuit (see Electrical Schematic
(GM3000)).
Testing with the Engine On
1. If the lamp is on with the engine running, shut off the
engine immediately.
2. Disconnect the gray wire from the switch.
3. Turn the ignition switch to ON. The oil pressure lamp
should be out.
4. If the light is still on, check for short circuiting in the
indication circuit (see Indicating and Safety Circuits).
Figure 58
5. Remove switch and install test gauge in the oil pres-
sure switch port.
6. Return ignition switch to OFF and connect the gray
wire to the switch.
7. Start the engine and check for a minimum of 21.7
psi (1.5 Bar) at 2000 RPM (with engine hot). If the engine
oil pressure is low, shut off the engine immediately.
8. Shut off the engine and remove the test gauge.
9. If engine oil pressure is good, replace the switch.
Groundsmaster 3000/3000–D
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Electrical System
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