oil pressure light

[Steveo50]

Hi,

I have a T25 1990 H reg 1900 DG engine water cooled, the problem i have is that the oil pressure dashboard light comes on at high revs (but no buzzer) have checked for electrical faults. Oil pressure is good, changed oil & filter and flushed out engine first.

The light comes on when started ; goes out when idiling but will then come on if the engine is revved but doesnt go out if idiling again. it does this even when both the oil pressure sensors are disconnected !

The engines sounds good and is running smoothly and no smoke ~ it drives well but the light keeps coming on....

Any ideas - have searched the forum and wiki but nobody seems to have the same fault.

Steveo50

[clartsonly]

this has to be an elecrtical fault perhaps a bad earth, does it always do it in the exact same way?

[Steveo50]

Thanks, yes it does it exactly the same every time. I have cleaned 2 earths on the engine are there any other ie. dash end?

[Grun]

Steveo50,
Sounds as if you have a partially working warning system, (light but no buzzer), and a break in the wiring or a faulty high pressure switch.

https://club8090.co.uk/wiki/Al ... and_causes" onclick="window.open(this.href);return false;

If the high pressure switch (near the water pump) wiring is open circuit, or the switch the wrong one or faulty, or if the oil pressure is low (of course!) you will get the light and buzzer when the revs go above about 2000. If you earth the wiring and the buzzer still goes, check for break in circuit somewhere (14 pin plug under dash cowl one suspect.)


To identify your wires:- When you switch the ignition on, (Engine not running) the oil light should flash. (No buzzer should sound)

Disconnect the wires one at a time and the one that puts the light out is the one which should be attached to the low pressure switch (between the push rod tubes left cylinder bank.)

Grounding (Earthing) the other wire will stop the buzzer as a temporary measure (if you are sure of your oil pressure of course !!!) That assumes the wiring to the buzzer circuit is sound, any break in the wiring and the buzzer will sound even with the wire end grounded.

Other places to check for continuity are..........
1.Connection at the white multipin connector to the PCB (back of 'clocks' on instrument panel). Pin 12
2.Junction T7/7 in the engine compartment relay box, (Forward left side).
3.Two pin connector T2 in the engine bay where both high and low pressure switch wires are (separately) connected.

Mike

[clartsonly]

do you have a tachometer (rev counter) fitted?

just wondering whether that is having an effect on anything electrical?