Help with oil light

[SpongerJim]

Hi,

I Have just had my 1986 1.9 DG serviced and now the oil light is coming on.

I have done quite a bit of searching but can't find anyone else with behaviour to match what I am seeing.

Our engine has 2 pressure switches.

On turning the ignition key the oil light flashes and the goes out when the engine starts. So far so good.

At tickover it stays off but then as soon as I drive away it starts to glow. As the revs increase it gets brighter but goes out as soon as I lift off the throttle.

I have checked the oil filter and its a Mann one, which I believe is recommended. I have changed the oil to SAE 20-50, which I understand can also be a factor.

Having read a couple of great articles -
http://www.gowesty.com/library_article.php?id=810" onclick="window.open(this.href);return false;
http://www.vanagain.com/buzzer2.htm" onclick="window.open(this.href);return false;

..this morning I disconnected both switches by pulling the connector just on top of the left rear cylinder.

When I restarted the engine I was surprised that the behaviour persisted - as the revs increased the light started to glow, getting brighter as revs went up. At some point the buzzer kicked in but this was expected behaviour as that is triggered by no signal above 2000rpm.

As this happened with the sensors disconnected I guess this discounts them being the problem but now I'm not sure how to diagnose where the fault lies.

Any suggestions of here to look next would be very gratefully received!

Thanks,

Jim

[SpongerJim]

Some further info...

I realised that the previous test was slightly inaccurate so I retested, this time with the low pressure switch disconnected and the high pressure switch line grounded so that the buzzer would not come on at high revs.

This isolated the warning light glowing behaviour so that at as the rev built the warning light would glow brighter and brighter.

I think that I can now safely assert that the fault is in the electrics somewhere, either in one of the lines that goes to the dashboard or the oil pressure "computer" itself.

I'd still be interested to hear from anyone who has been through similar woes.

Thanks,

Jim

[MidLifeCrisis]

Assume you've had a good clean of all the usual ground connectors?

[SpongerJim]

I need still to check everything in the cab. Probably a job for next weekend!

Thanks,
Jim

[SpongerJim]

Just for the record this was fixed by sorting a lose circuit board under the speedo binnacle cover.

[Aidan]

thanks for posting the result