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TR6Dan
01-10-2019, 03:59 PM
I noticed the last time I drove my car the low oil pressure light took a half mile or so of driving to go off. The oil level is fine and the oil pressure gauge says 75 and the lowest 50. Could it be the oil pressure switch or another item needs replacing? Dumb question; but what is the purpose of both a light and gauge?

Thanks,
Dan

dklawson
01-10-2019, 04:14 PM
The switch is for alerting you with the sudden appearance of the colored light in your line of sight. It might be a while before you notice a low reading gauge.

Switches do go bad. I would replace it with a known good one as it is the least expensive first step. A second step would be to use an aftermarket, cheap pressure gauge to confirm the one in the dash is reading correctly.

Tybalt
01-10-2019, 11:05 PM
This is going to sound odd but IIRC there is tie in with the oil pressure light and the PDWA* electrical circuit. I had a similar problem, faint glow of the oil pressure light that would come on and then go off after a while, when I first bought my TR6 in the 1988. It turned out that the brakes had not been bled properly and the PDWA piston was not well centered. I bled the brakes to center the PDWA piston and the problem went away. Another way to center the piston if it isn't too far off center would be to remove the switch on top of the PDWA and use a small screwdriver or punch to move the piston and center it. There is a pretty good bit on the Buckeye Triumphs website technical articles that discuss rebuilding the brake master and PDWA. You can see what the piston looks like and how the PDWA switch rides in this necked down portion of the the PDWA piston.

https://buckeyetriumphs.org/technical/Brakes/MCPDWA/MC.htm

*PDWA - (Pressure Differential Warning Actuator) just in case you are not familiar with it, it is part of the brake system to warn you of a loss of pressure on either the front or rear hydraulic circuit

poolboy
01-11-2019, 11:37 AM
The PDWA switch when grounded can activate the BRAKE light, but the not the Oil Pressure warning lamp....on the other hand low oil pressure will illuminate BOTH the BRAKE and the Oil Pressure warning lamp. However both lamps will be rather dim due receiving only 6 of the 12 volts
If the OP warning lamp does go out after a half mile or so as Dan described I doubt that the problem is the PDWA itself.