Generac — Test 39 - Check Oil Pressure Switch
Testing & diagnosis
From a Generac service manual covering: 4700, QuietPact 40, QuietPact 40 LP, QuietPact 40G, QuietPact 40LP. Check it applies to your exact model before use.
Applies to: Generac 4700, Generac QuietPact 40, Generac QuietPact 40 LP, Generac QuietPact 40G, Generac GH-220 engine
Procedure
- Check engine oil level, replenish to FULL mark if necessary
- Set VOM to Rx1 scale and zero meter
- Connect meter leads across switch terminals with engine shut down; should read continuity
- Crank engine; meter should read infinity once oil pressure opens switch contacts
- If contacts do not open, remove switch and connect oil pressure gauge in its place; start engine and measure pressure
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Oil pressure should be above 10 psi
Full service-parts list: Generac 4700 →, Generac QuietPact 40 →, Generac QuietPact 40 LP →, Generac QuietPact 40G →
Source: Generac service manual. Steps and values are as documented; always cross-check against the official manual and any later revisions for your exact serial number before servicing.