What should the oil light do when starting?

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WhiteWesty82
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What should the oil light do when starting?

Post by WhiteWesty82 »

Hello,

I have a question about my 1.9 DG Westfalia California: When I turn the ignition key to the first position, the oil warning LED (very briefly) illuminates then goes out before the engine starts. I changed the blue low pressure switch between the pushrod tubes this morning, the light behaves the same as before. Is this how it should work? If not, could someone describe how the LED should behave when starting, or point me at a link to a thread on how to check the wiring associated with it? Probably a daft question but I want to check its behaving ok or not, and I cant remember how it should operate! Thanks

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Re: What should the oil light do when starting?

Post by MidLifeCrisis »

Are you saying that the light goes off 'before' the engine starts?
So, if you have the ignition switch in the first position (and do not start the engine) - does the LED light then go out (with the engine still not running)?
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Mocki
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Re: What should the oil light do when starting?

Post by Mocki »

The light should come on and remain on until oil pressure is ok, usually after the engine has turned before it starts .
It should not go off before you turn the starter .

On later models it flashes rather than solid illumination until the engine starts
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WhiteWesty82
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Re: What should the oil light do when starting?

Post by WhiteWesty82 »

Thanks for the replies, in answer to your questions; when the key is turned in the ignition to the 1st position but no further, the oil light goes on for about 1 x sec then goes out (with the engine not running). If I then turn the key to the next position, the starter engages and the engine starts running, but the led stays off I don't think it is working as it should do but not sure where to check next. Any ideas?

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1664
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Re: What should the oil light do when starting?

Post by 1664 »

Hmmm, my oil light flashes for about 4 seconds before going out regardless of whether I start the engine or not and always has done
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AngeloEvs
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Re: What should the oil light do when starting?

Post by AngeloEvs »

What year is your van? The oil pressure warning system is different on later vans with the oil pressure led controlled by the DOPs board fitted in the speedo. Earlier vans use the simpler method with the led connected directly to the oil pressure switch.
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Re: What should the oil light do when starting?

Post by WhiteWesty82 »

It's an 89 model - I missed that from my 1st post. I'm wondering if somewhere the low pressure sensor wiring is shorting to ground. I'm going to start with the engine bay sensor wiring and then check the multi plug connector in the dash... time to dust off my multimeter.

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Re: What should the oil light do when starting?

Post by ajsimmo »

No, it's not shorting to ground. Just the opposite, it's not "seeing" a 0v or ground signal at the switch. Most probably broken wire, and it's most often at the twin connector near the thermostat housing. A very common fault. Or sometimes it's a bad connection on the multiplug at the back of the clocks. Give it a gentle wiggle.


Edited for clarity:
With the low pressure switch disconnected (or if there's a fault) the oil light will flash very briefly at ignition on just to test the LED and shows you it (and the DOP system) is working.

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Last edited by ajsimmo on 25 May 2020, 17:56, edited 1 time in total.
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Mocki
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Re: What should the oil light do when starting?

Post by Mocki »

1664 wrote:Hmmm, my oil light flashes for about 4 seconds before going out regardless of whether I start the engine or not and always has done
Yeah I see I worded that badly ,
I should have been clearer
Should have said "on later vans the oil light flashes and self tests, rather than a solid red light staying on until engine starts on older vans "

Not sure that makes any more sense either lol
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Re: What should the oil light do when starting?

Post by WhiteWesty82 »

Cheers all sorted! Both oil pressure switches fed into a plug in the engine bay near the thermostat housing and then go forward to the back of the dash. I tested the continuity between the plug in the engine bay and the dash which were both fine. Also gave the 14 pin plug a quick spray with contact cleaner. Turns out the wire from the LP switch to the engine bay plug was broken somewhere inside. I replaced that wire, and the oil led now flashes when the ignition is in the first position and goes out when the engine starts (as it should). I was a bit worried it was an issue behind the dash for a bit! Thanks for the advice.

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