The brake pressure adapter is basically a T-piece that simply replaces the union bolted on the bulkhead that connects the flexible pipe from the block to the pressure gauge on the dash.
With the ignition on, the switch contact closes at pressure P>~20psi and operates parallel to the oil gauge. The switch is connected to a relay and the relay is powered on at P>20psi. The normally closed contact on the relay then de-activates the warning lamp.
Fig 1 – Main kit, comprising oil pressure adapter, sample warning lamps and pre-wired relay module.
Fig 2 – Original oil pressure union. The oil pressure adapter replaces the existing union on the bulkhead.
Fig 3 – Pressure adapter installed and connected. It is mirrored to clear the coil and the copper pipe receives an S-bend.
The relay module (see Fig 1) is pre-wired and mounted in a plastic case which can be fitted behind the dashboard or the scuttle panel with Velcro strips.
The kit includes the wiring from the pressure switch to the relay module. The polished and lacquered warning lamps shown are available as an option.
Fig 4 – Samples of the warning lamp.
This is how it works:
Ignition – ON, engine OFF, no oil pressure, Warning light.
Start engine, when P>20psi Warning light OFF.
Engine ON, p<20psi, Warning light ON.
The warning light stays on until reset by switching off the ignition.
I have also developed a further slightly more complicated module which enables a buzzer to be connected.
When the ignition is switched on the buzzer is off and receives an operation permissive once the engine has been started and the oil pressure exceeds 20 psi. The buzzer going off every time the ignition is switched on would prove annoying. For this reason a test button is fitted to the circuit to enable the buzzer to be tested. This is how it works:
Ignition – ON & engine OFF, & no oil pressure, →Warning light ON & Buzzer OFF
Start engine, when P≥20psi →Warning light OFF & Buzzer OFF,
Engine ON & P<20 psi, →Warning light ON & Buzzer ON.
The warning light and buzzer stay on until reset by switching off the ignition.
This circuit is designed for cars with positive or negative earth.
Fig 5 – Buzzer module undergoing testing.
Fig 6 – Warning lamp combined with indicator lamp.
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