Oil Pressure Light and Buzzer on at Hot Idle

[tollertdi]

This combination is supposed to be an impossibility since my '83 Diesel Rabbit is obviously not at 2000rpm at idle.

So maybe the speed sensor on the alternator is sending some kind of noise to the dash? Well I pulled the W terminal cable off of the alternator and the buzzer/light did not go off.

Again this only occurs at hot idle. Any ideas??

[coke]

On my 84 Jetta, I had to disconnect the W-terminal, remove the clip off the oil pressure sender on the filter flange, and ground the sensor wire. I left the one in the head connected.

[82vdub]

Again this only occurs at hot idle. Any ideas??

Hot means that the oil is thin, and idle means that the engine oil pump is pumping the least quantity of oil it will pump. The short answer is to take a mechanical gauge and check your oil pressure, as fast as you can! Without knowing what oil pressure you have, you're still guessing if it's an electrical problem, sensor problem, or another problem, when the system may be working just fine because you may have low oil pressure.

[coke]

If you want to hook up a mechanical gauge to check, I can provide you with a little bit of information you might find useful.

As you're probably aware, the sensor unscrews out of the filter flange. The threads are M10x1. Should be helpful to in hooking up a gauge for you to check with.

[Fatmobile]

If it's happening before 2000 RPM, it could be the other oil pressure switch, the one on the head.

[tollertdi]

According to Vince's troubleshooting link:

http://vincewaldon.com/index.php?option ... &Itemid=28

the low pressure is not involved here. I'm getting the buzzer plus a flashing red light at hot idle. This is only supposed to happen in the high pressure circuit above 2000 rpm. Apparently this is not an uncommon failure but no one has troubleshot it to a resolution.

I guess Coke had the problem also, but looks like he still doesn't know why it's occuring. By grounding the sensor wire he forced the control system to think that the sending unit is in the closed position, thus the control system thinks that the oil pressure is above 20 psi. Under this situation, I don't think you have to disconnect the W terminal also?

Here's another case from Vince's post:

written by Talon, April 07, 2010
I have 1.8 Golf and the Oil light comes on and the buzzer sounds at low RPM (engine warmed up)and they go out if I rev up the engine? No lights or buzzer while cold. It would seem to be a low pressure situation but with the high pressure warning?


This is exactly the problem I have also....

[the vegenator]

I looked around for a thread on installing an aftermarket oil pressure gauge, but I guess I didn't look hard enough... instead I coaxed some info out of MizPahPah. Hope he doesn't mind me spreading his knowledge:

I used regular oil pressure gauges with the plastic hose. Instead of using the plastic I used copper to feed the gauges.

at the engine I got brass 3/8 ntp treaded pipe ran a metric die on the end that goes into the head and oil filter flanges then tapped one end of a t metric for the stock pressure senders.

Then used the fittings from the gauges for the rest of the install.

I used just enough pipe tape to seal / lube the connections but not enough that it affected the restance to ground for the stock pressure senders.

I'd love to see a picture of the filter flange so I can get a better visual of how everything hooks together.

[82vdub]

I'd love to see a picture of the filter flange so I can get a better visual of how everything hooks together.

You would install a "T" or "Y" fitting in the head or filter flange and install the factory switch in one of the ports, and pipe the mechanical oil pressure gauge to the other side. I did this on my old Ford, so that if I don't look at the pressure gauge I installed, the idiot light will at least come on in the dash to alert me to something.

[82vdub]

According to Vince's troubleshooting link:

http://vincewaldon.com/index.php?option ... &Itemid=28

the low pressure is not involved here. I'm getting the buzzer plus a flashing red light at hot idle. This is only supposed to happen in the high pressure circuit above 2000 rpm. Apparently this is not an uncommon failure but no one has troubleshot it to a resolution.

I guess Coke had the problem also, but looks like he still doesn't know why it's occuring. By grounding the sensor wire he forced the control system to think that the sending unit is in the closed position, thus the control system thinks that the oil pressure is above 20 psi. Under this situation, I don't think you have to disconnect the W terminal also?

Here's another case from Vince's post:

written by Talon, April 07, 2010
I have 1.8 Golf and the Oil light comes on and the buzzer sounds at low RPM (engine warmed up)and they go out if I rev up the engine? No lights or buzzer while cold. It would seem to be a low pressure situation but with the high pressure warning?


This is exactly the problem I have also....

You'll also note that vince said that you should verify what your oil pressure is. I would suggest that this be done or else you are assuming that it's an electrical issue, without knowing what your oil pressure really is.

[Vincent Waldon]

Just to weigh in here:

- yup, it's always a really good idea to confirm your oil pressures... you'll sleep much better at night when you know that it's the smoke detector that's at fault and not a raging fire in the basement
- yup, you shouldn't get a buzzer at anything under 2000 RPM... and if you are, there's really no further troubleshooting possible since it's the oil pressure warning circuit (a circuit board that's part of the cluster) that's very likely (99%) at fault. Swapping out the cluster with a known good one would be the smoking gun... there's no combination of broken sensor or alternator wiring that should be able to trick the cluster into thinking the engine is above 2000 RPM.

My guess... your cluster *is* defective and it's watching both sensors all the time...at hot idle your oil pressure is naturally low enough to trip the high pressure sensor. If you don't want to swap clusters you can delete the hi-pressure side of the warning system (assuming there aren't any other defects in the cluster) by grounding the wire to the hi-pressure switch... you'll still have the low pressure light that almost all other cars in the universe have used for decades.

[im_n2_vws]

I would have to agree with guy saying to check the pressure first. I have had this same problem on my 8v gasser. The first thing I did was make sure I had good oil pressure. I do have good pressure on both the high and low sides, I just have to listen to the buzzing once in a while. My Dads 1.6 na diesel is the same way. You could end up having a bad oil pump or sludge in the oil pan. Usually happens when I make a turn at idle or slow down.

[tollertdi]

I plan on checking my oil pressure just to make double sure.

But, again this is a totally abnormal diagnostic with the buzzer on and the light flashing at idle. The normal diagnostic is to get a solid red light without the buzzer if you have low oil pressure at idle. I guess the previous poster also has a VW with similar symptoms.

Again the system is designed to give you a buzzer + flashing light ONLY when you're above 2000 rpm.

[Quantum TD]

Couple o thoughts:

1) Yes, getting actual pressure confirmation is a great idea.

2) 1983 Rabbit does not have the integrated oil warning circuit in the cluster. That's only on German-made cars, and post-1985 Golfs and Jettas. On the 83, the oil light is controlled by a relay (usually long and yellow). It could be bad.

3) Another possibility: Is your car equipped with an upshift light (idiot light on the lower center of the cluster with an "UP" arrow? If so, your problem may be related to that circuit. The upshift light circuit gets its power through the same source as the oil buzzer relay, and both are plugged into the W-terminal on the alternator. If you find a thick black wire in your engine bay with a female blade terminal end on it, that's probably your problem. Connect it to the W terminal on the alternator, and the buzzing should stop.

I had this problem on a 1984 Rabbit D I had. I powerwashed the motor, and suddenly, the oil light started buzzing. I figured it out. Since then, the guy who bought the car from me has had it pop off on him several times.

[tollertdi]

Thanks Quantum for the info.

On point #3, I do have an UP arrow. VW put them on all 83's, 84's and most 82's (Rabbits). My W terminal is hooked up, I've already checked that. If it wasn't hooked up I believe I would be getting the buzzer all of the time? I only get it at hot idle. Which brings up another possibility. Maybe what's happening here is the W terminal voltage pulses at idle are dropping to a level where the control system thinks the W terminal is unplugged. Could be caused by a higher than normal impedance in the circuit or a bad ground.


"2) 1983 Rabbit does not have the integrated oil warning circuit in the cluster. That's only on German-made cars, and post-1985 Golfs and Jettas. On the 83, the oil light is controlled by a relay (usually long and yellow). It could be bad."

Fabulous info... I didn't think there was anything on the cluster. This maybe part of the problem. Can you give me any hints on where this device is located?

[MizPahPAH]

I finally took a few pictures of my oil pressure setup











I got all the parts for this from local hardware store 3/8" ntp.
Tapped the short piece of pipe and 1 end of the t 10mm and used a little pipe tape
not too much that it changes the resistance of the stock switch to ground.

the copper pipe came from NAPA.
No problems so far and I have been running it 2 years.

My oil pressure is WAY high on cold startup right around 100psi and higher if I dont let it warm up.

I tried three diffrent oil pumps two used on brand new all same high pressure.