Low oil pressure buzzer...Fixed

[Trimster]

UPDATE:  Left the buzzer box under the dash, pulled the high pressure side connector off the oil filter housing and formally grounded it. No buzzer. Nice!  I have a mechanical gauge in the cab so no need for that irritating thing.  Thanks folks for the help.

bob
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I get the low oil pressure light and buzzer when idling. the pressure is rock solid at 25 lbs... but the oil pressure sensor has a 27 stamped on the side. I'm assuming that's it's low point trigger. I'm not worried about the 25 lbs. Bit the buzzer is driving us nuts.
A- can a 20 lb pressure sensor be found. (what car, make, model am I asking the parts store for?)

B- if I pull the black buzzer box from the fuse box, will it bother anything else?

thanks

bob

[somolovitch3]

Where are you measureing the pressure?

low oil pressure switch is at the head, Black body (?).

high pressure is at the filter housing (hmmmmm, brown body?)(Tyler, you know this stuff, a little help on switch ID?)

[Trimster]

Ok, black box that I pulled on fuse block was for the open door w/key in buzzer.

I am pulling the oil pressure reading (mechanical) off the end of the head. Both oil pressure sending units have been replaced.

Mechanical gauge says 24psi at idle when up to running temp.

The number stamped on the side of the new sending unit is '27'. If that is an indication that it is set for 27psi, then that would explain the buzzer going off and it's proof it's working. maybe I have the wrong sending unit? I did get it from my normal parts store that is specifically foreign parts and really specializes in all things VW... but that does not mean it's not for at TDI instead of a normal aspirated diesel.

Where is that irritating buzzer located by the way?

[Trimster]

possible but not likely. The warning started after the head gasket blew. Wiring was factory/working fine until the the head gasket thing. At that point I did replace the sensors, one at a time to trouble shoot. No change. I then installed the gauge to see what was up for real.  That's the course of action I have taken so far.

I will do a check on each with a meter this afternoon... when it stops snowing here in Utah.

bob

[Trimster]

OK. I pull the wire on the pressure sensor on the head, nothing happens. there is 12v at that wire. I ground that wire and nothing happens with the buzzer.  I pull the wire on the sensor at the oil filter... buzzer goes off.

What does this mean?

[Vincent Waldon]

The buzzer is triggered by the sensor on the filter flange... the high pressure (1.8 bar  or 26.5 psi for a non-turbo engine) sensor that the cluster pays attention to only when the engine is 2000 RPM or over.  Below 2000 RPM  the cluster only listens to the sensor on the head, and only trips the light.

So, if you can confirm you've got:

- at least 1.8 bar / 26.5 psi of pressure
- at the filter flange
- with the engine at normal operating temperature
- at 2000 RPM

and you're still getting the buzzer then it's almost certainly the sensor.. good thing they are 5 bucks or less.  

The fact that you're getting a buzzer at idle is strange... not supposed to be possible... but start by making sure you have a the right sensors in the right places and a good solid connection to the W connection on the alternator so that the cluster knows what speed the motor is going.

It's real common to have part stores get confused... one sensor is low pressure, normally closed, and the other is high pressure normally open.  

Using a test light or multimeter, the sensor at the filter flange should show open with the engine off, and grounded with the engine reving enough to make 27 psi or more.  The sensor at the head should show grounded with the engine off, and open at idle.

Speaking of grounded.... perchance did you use teflon tape on the sensor threads ??  Another common oops...


Vince

[Vincent Waldon]

Yup, that's a logical explanation.  

Technically you should never be able to get a buzzer at idle.... if you do, it suggests the cluster circuit is busticated (technical term).  

You could replace the cluster, *or* defeat the high-pressure circuit by grounding, and you still have a fully functioning low-pressure circuit... much like 95% of all the cars in the universe.  

Of course, then you don't have all those interesting "my buzzer comes on when I come back to town after racing down the highway" conversations... ;-)



Vince

[Trimster]

I have grounded that wire (oil filter) for tomorrows runabout. Actually, I think I just might do that long term. I now have a mechanical gauge in the cab so buzzers and idiot lights are kinda redundant at this point maybe.

[saurkraut]

On My '84, had new sensors and still had the oil light at idle with the 36MM pump on a fresh rebuild.

Pulled the yellow relay, threw it in the garbage.  Jumped the two sockets that had the blue/black wires.

I get an oil light when I turn on the key.  When the engine starts, the oil light goes out.

Who in the heck needs a high pressure warning anyway.