Oil Pressure Warning Light Inoperative

[keynsham1]

After having my van for ten years, it has just occurred to me that the oil pressure LED does not come on! I think I had assumed that it only came on if there was an issue and I know the buzzer works because it went off one day because the block connector had worked loose on the dash.

So I have just tried to coax it into life by disconnecting the plug in the engine bay where the two oil pressure switches plug in, and earth each input. Still no light. So I begin to wonder if the LED has had it? It seems easy to replace but my question is, how big is it? I can get one from the usual suppliers but they are £10 plus P&P which is loads for a 12v LED. I am guessing 5mm but I haven't looked yet. Does anyone know?

[keynsham1]

AI Copilot tells me this....

The 171-919-061/B LED is a small instrument panel warning light used in Volkswagen vehicles (like the T25, Golf Mk1/Mk2, Scirocco, Jetta, and Vanagon). It is not a standard "5mm LED" you’d buy off the shelf, but rather a specialized indicator lamp designed to fit into the dashboard cluster. Its physical size is roughly that of a small dash bulb (about 5–6 mm diameter), with a compact housing to slot into the warning light panel

So I guess a tenner it is!!

[keynsham1]

It seems that the LED's are in fact 5mm and 2-2.2V which is totally standard. I just took one out and measured/tested it!I box of 200 of various colours is £4.50 on Amazon. Incidentally, this has not solved my oil light issue. Even with a known working LED fitted, I still get no light!!

Copilot, and therefore AI, get it wrong again!!

[Rik]

Curious what it turns out to be. I currently have the same problem, after having my dash out and quite a lot of work in the engine bay.

[Robsey]

I recently repaired a very tired cluster.
None of the LEDs worked.

They are indeed 5mm diffused LEDs,
2 to 2.5. Volts sounds about right.
Bear in mind, back in the 80s there was no such thing as high-brightness LEDs.
Nowadays they are all high-brightness LEDs.

When I repaired the dash, the LED's were fitted the wrong way round.
Wrong polarity.
Fitting the correct way round sorted my issue.

Is yours fitted right.?

It seems odd if the buzzer works but not the led, unless it is an LED or foil issue near the led or it's resistor.

[keynsham1]

The LED was not the fault, and yes I see what you mean about high brightness!!!I have basically given up trying to fix it now and ordered a replacement loom from SHC to get rid of the old PCB. It is definitely that which is causing the issue. It has delaminated in places. I tried adding some new wiring to bypass the damaged areas but it just doesn't really work. The oil light can be coaxed to come on very dimly with some wiggling of the PCB but basically it is toast!!

[keynsham1]

SHC wiring loom kit and rev counter arrived to day and it is fitted and is brilliant. I still have one issue though. When I start my engine the oil light doesn't quite go out but glows very dimly. It did this before I fitted the kit so I know it isn't that. There seems to be  some volts getting to it when there should be none. I tried starting the engine with the high pressure switch disconnected as that is the only one easy to reach but it didn't help. I will change both the pressure switches as a matter of course. I guess if the low pressure switch is still allowing a small drain past when it is supposed to be open then that could be it. Tomorrow I will try and pull the wire off and see what happens then when I start it.

Just wondering if anyone else ever had a similar issue?

[keynsham1]

Really scratching my head now! I have disconnected both oil pressure switches and replaced the buzzer of doom circuit board with a replacement and still the oil light insists on dimly glowing when the engine is running. It is completely out as you would expect when the engine is running. 

So I have totally new wiring from SHC and have replaced the circuit board and tried with disconnected oil pressure switches and even run with the fan belt off, all to no avail!

As the oil pressure light is only powered from the buzzer of doom circuit board, and as that board is assumed to be OK, I can only assume I have a feed coming from somewhere in the wiring before it gets to thew instrument console, but only when the engine is running!

More puzzling over the wiring diagram is needed I think!!

[Robsey]

I recall dueller having issues last year with instrument wiring defying logic.
His turned out to be chafed wiring under the van.

I wonder if you have chafed wiring too, where the inner conductors are shorting to earth.

[Mocki]

Have you tried running a temporary wire from the engine bay to the dash ? Old wires become high resistance internally with constant hot cold and vibration , i had a similar issue with main beam tell tale years ago, ran a replacement wire and stopped the dim confusion 
might be worth a try for the sake of half a hour and 20ft of wire draped through the van 

[keynsham1]

That is my next move. I just removed the two wires from the multi plug at the instrument cluster end which come from the two oil pressure switches and the light now does not come on when the engine is started so i can only assume it is one of the wires breaking down somewhere under the van and allowing a poor earth but enough to let the LED glow.

So I will try new wires from the engine bay to the plug next which I am sure will sort out the problem! I will then run them properly under the van. I also have an oil pressure gauge which is electronic so I need to put a wire in for that too at the same time. I am still working out exactly how I am going to fit the pressure sender for that.... but that is a whole new thread!!!

[Mocki]

You will just scare yourself with an oil pressure gauge , save your self the pain …….