7 replies to this topic

[callMeMayfair]

Hi all, I'm hoping to get any advice on what next to do.

I recently restored my mini including engine rebuild. on putting her back together, all seemed well.

The orange oil light used to come on when the ignition was on, then go off after engine start. The other day

the orange light stopped coming on. 

why!?

So far, I've tested the oil pressure switch for continuity and all seems fine. I've also tested for continuity from the pressure switch lead to the block on the dash with success here too. Finally I've tested continuity on the printed circuit board, again with a with no visible issues and changed the bulb.

Just for good measure, I ordered a new switch and changed that. Still no light.

Should I check resistance on the lead? does anyone know what to expect as a reading?

any help will be greatly appreciated. I really want this on the road but i have few small issues to address before mot.

 

its a mini Mayfair 1989 carb if it helps. All other lights on the dah come on as expected as well as the rev meter working well.

 

Thanks all.

[nicklouse]

Changed the bulb?

[xrocketengineer]

Can you check for voltage on the bulb in the printed circuit? if you can then with the pressure switch disconnected and the ignition switch on (engine not running) there should be no light and 12volts on both sides of the bulb. Connecting the pressure switch should provide an earth path to one of the bulb sides. If the voltage on both sides of the bulb is still 12 volts, your wire to the pressure switch is bad. If the voltage on both sides of the bulb is 0 volts, then your supply side is bad. The printed circuit is not providing the proper voltage to the bulb.

[callMeMayfair]

Can you check for voltage on the bulb in the printed circuit? if you can then with the pressure switch disconnected and the ignition switch on (engine not running) there should be no light and 12volts on both sides of the bulb. Connecting the pressure switch should provide an earth path to one of the bulb sides. If the voltage on both sides of the bulb is still 12 volts, your wire to the pressure switch is bad. If the voltage on both sides of the bulb is 0 volts, then your supply side is bad. The printed circuit is not providing the proper voltage to the bulb.

Thanks for this, I'll give it a try after work today.

[andyapanel]

I would check the lead. They seem to become a bit fragile with time
Hope it’s an easy fix

[sonscar]

Meters have their place but for this type of fault a wire with a croc clip is your friend.The electric goes through the lamp to the sender which connects it to earth.Connect the wire to earth with the clip at the sender and the lamp should light.If not go to the nearest connector to the lamp and try again.If no light try a lamp in series with your lead and connect it to the feed for the lamp.A test probe is essential for elderly auto work in my view.Either the battery is missing or the earth is missing,Steve..

[Steam]

The best way to check is to first take the connector off the switch and earth it to the block which should turn the dash oil light on.
To test the switch, use a test light connected to 12v pos and to the switch terminal should light the test switch.
From here you can eliminate and trace.

[callMeMayfair]

Thanks all for the advice. After extensive testing, it seemed the culprit was the printed circuit board. After doing the check as suggested by learner driver, I eventually found  a  hairline crack in the ribbon that connects to the block. As I was testing, the block was out so the crack seemed to join and I was getting voltage. After a by chance bending of the ribbon on a test I lost voltage, which led me to check the connections.

I simply soldered the crack and all is working fine now. So may hours scratching my head.

 

As a tip to future readers, including all the above advice, check the circuit board fully for this. 

 

[media]

Edited by callMeMayfair, 17 August 2022 - 07:35 PM.