Flashing Oil Pressure Light

[Asymtave]

You can't really check individual electronic components while they're in the circuit. All the other stuff in the circuit (that they are soldered to) will throw off the readings. They have to be removed completely to accurately know what's going on.

You can measure voltages at various parts of the circuit, but that's about it without de-soldering or cutting wires.

Eric

[CoolAirVw]

Spend 50 hours fixing oil pressure light? ---crazy ? ---you do not know CoolAirVw.

I'm the one who fabricated his own exhaust. Got extimate for 150.00 but instead spent 22 hours building it myself because I found a muffler on the side of the road.

I grew up a Dirt Poor Missouri HILLBILLY ---couldn't afford a nice car --I was broke so I bought a broke car, so I had to learn to fix em. Ended up fixing cars for a living.

Old habits hard to break. If I fix it---- I love it.

I'm new to VW diesels but I learn quick ---- can I contribute anthing worthwhile ? ---time will tell.

The line between Genuius and insanity is thin and hard to define" Yes I can fix the VW diesel but Why?? (says my wife and the guys at work)

I promised to fix the light ? --ok I do it, and I document the SAGA here.

Given enought time CoolAirVw can fix anything? --- yes IMHO

The Chick Magnet (my Jetta) purrs like a kitten and will literaly SMOKE anyone behind her!

Enough for now.

[Fatmobile]

Ah hahaha.
coolair hagar
fatmobile was thinking the other day, could this be something to do with the trany reverse light switch plug thingy?
Does it have anything to do with telling the instrument cluster at what RPM the engine is running?
It has something to do with the upshift light right?
...and it doesn't work well for the reverse lights why would it work for any of the other tasks it has?

[tylernt]

Ah hahaha.
coolair hagar

I'm glad I'm not the only one that saw a similarity...

[bhtooefr]

I think it was intentional.

The tranny reverse switch has nothing whatsoever to do with sending RPMs.

It has two functions.

One is to turn on the reverse light in reverse.

The other is to turn OFF the upshift light in reverse, neutral, and fifth, no matter how many RPMs the upshift circuit is reading from the alternator.

However, my theory is that the upshift light circuit is screwed, and is somehow triggering the oil light.

That's why I was asking on the operation of the reverse switch. If it was working correctly, that would blow my theory right out of the water. If it wasn't, though, my theory still works.

[CoolAirVw]

Ok. More info in my Saga to fix the cursed Flashing OIL PRESSURE LIGHT.

I'm still wondering if part of my problem is due to having a GAS OPCU. Despite all the math in the previous post regarding RPM of Gas Vs. Diesel I'm still not sure the OPCU is wrong or right. As you may recall I tripped and stepped on my OPCU breaking it into 3 peices.



I posted "OPCU wanted" and Looks like FineFrank is going to send me one. AWESOME. THANKS AGAIN FRANK.

[CoolAirVw]

But I want to know if a Gas OPCU will work in a diesel. So today I called up my freindly local dealership. "Whats a Oil Pressure Control Unit" he said. I said just fax me the instrument cluster and I'll pick it out for ya.
He sent me the following.


Notice 14B (circled on the left) has 2 models. Diesel and K-Jetronic.

So Vw has 2 part numbers.
Diesel 321 919 064 N
Gas 321 919 064 M

Important note: This is for my car. 85 Jetta. Part numbers may not be suitable for other models.

Diesel OPCU is still available. He said he could get it in 3 days. For the LOW, LOW price of $137.00.

Needless to say I didn't order one. Thanks again Frank!

[CoolAirVw]

My saga is almost over!

Will post fix later. Wise man once said, "There are no tough problems. We just miss something in the basic checks." (I said that.)

[surfcam]

I was mentioning earlier about swapping the gas cluster. There are three things that aren't working the tack, glow plug light and high beam indicator. I thought everything but the tack should work so I'm now thinking it's a problem with the gas cluster.

4BTA 3.9 Cummins Stepvan
86TD Golf
91TD Jetta

[CoolAirVw]

Here's what I did wrong and what fixed my flashing oil light.

Remember the LOW PRESSURE SWITCH is normally closed and the DYNAMIC OIL PRESSURE SENDER is normally open.

I have a used motor sitting in basement (later project). I took the LOW PRESSURE SWITCH out of that motor, because it was easier to get out than the other, and tried replacing the LOW PRESSURE SWITCH on my car. It didn't fix it so I put the original back in. Then since I already had a "known good switch" removed from the used motor (I assumed the 2 were the same), I tried replacing the DYNAMIC OIL PRESSURE SWITCH. I never removed the DYNAMIC OIL PRESSURE SWITCH from the used motor in the basement.

All the quotes below are me.

Checked used senders with Ohm meter. THey do ground when engine is off (no oil pressure) and do not ground when engine is running (oil pressure).

Right there in my first post is the problem. Unfortunatly at that time my understanding of how the system worked was wrong. What this post should have said, if the switches were right was, "DYNAMIC SWITCH grounds when engine is on, and LOW PRESSURE SWITCH grounds when engine is off."

I checked voltage provided to the senders on the wires. Has 12V on both wires. I monitered this voltage while driving and as the light starts flashing there is no change. Meaning the senders are not grounding and the wire is NOT shorting to ground.)

This also shows the problem, although I thought it meant the OPCU was causing the problem. If the switches were right this post would have read, " While driving there is 12V on wire to theLOW PRESSURE SWITCH and 0V on the wire to the DYNAMIC SWITCH ."

I verified that if I ground the wire to the top sender that the oil light flashes. If I ground the wire to the Lower sender then the oil light does not flash which is interesting but I am ignoring this for now because it seems that this problem would cause the light not to flash.

Note: I made above check at idle. Once again at the time I didn't understand that the OPCU only looks at the Lower sender (Dynamic switch) above 2000 rpm. Plus if I would have grounded it above 2000 rpm it wouldn't have flashed the light. Because its supposed to be grounded above 2000 rpm. If its not grounded above 2000 rpm then the light does flash. (that was my problem)

So my Light was flashing now because I had a normally open LOW PRESSURE SWITCH in the DYNAMIC SWITCH hole (should be normally closed switch).

So why was my light flashing before I changed it??? I had put the switch I back in the used motor in the basement. I removed it again and checked it with air pressure and an ohmmeter, and it is normally open also! Someone as dumb as me had done the same thing!

So I fixed it by taking the DYNAMIC SWITCH out of the used motor and installing it in the DYNAMIC SWITCH hole. After 5 minute road test the light never flashed.
Note: The DYNAMIC SWITCH is white and the other is black.

WOOO--HEW! Car is fixed! SAGA is ended.

[CoolAirVw]

Just a side note.

If I had never tested a thing and just bought a new DYNAMIC switch and installed it, it would have fixed my problem, but only if I was lucky enough to get the right one and get it installed in the right position. How would I have got the right ones and known where to put them if I didn't have the knowledge that I now have?

[Fatmobile]

This info is going to help alot of people because as you know you aren't the first person with this problem.

[JSMCLAUGHLIN]

Hi all, Hey I feel for you. I've had my 85 Jetta for around a year now and i've been turning up the radio to overpower the annoying little buzzer. I also changed sensors, tested wires. What I'd really like to know is where is the little buzzer located so I could rip it out! I also checked pressures and they are good but I have not replaced any of the instrument cluster. I just want to kill the buzzer not my Tach. I will find that thing and kill it soon.

[bhtooefr]

OK, use your Bentley (you do have one, don't you? if you don't, use this instead: http://ep0niks.ctech.ca/vw/eva2 ). It'll tell you where the oil pressure switches are. Try switching them around. If that doesn't help, switch them back and try replacing them. If THAT doesn't help, then look at the cluster.

[CoolAirVw]

JSMCLAUGHIN

What I'd really like to know is where is the little buzzer located so I could rip it out!

The buzzer is on the OPCU (oil pressure control unit). The first page of this thread has a picture of the instument cluster and the OPCU is listed. The buzzer is pictured in the 3rd page of this thread in the picture of the "stepped on" (broken) OPCU. It is the little device on the farthest right peice. It looks like a relay.

I would recommend trying to fix it before you disable it. You could probably disable it temporarily while you fix it by bolting the wire to ground on the switch on the oil filter and by unplugging the switch on the head.

There is lots of info on this thread that would help you to fix it.