blinker / e flasher problem 67 12v

[Eric&Barb]

[shanks]

Thanks to all here I have made a bunch of progress. Went through all the wiring and corrected the problems. Fuse 8 is now hot all the time, fuse 7 is hot with the key on, the bus starts and shuts off as it should, lights all work. I also now have a working generator light and blinker indicator. My final thing is the oil pressure light, it does not light up. I checked continuity of the wire from the engine to the speedo. I have a new bulb and holder installed with continuity through the bulb, from the tab to the bulb holder, and from the tab to the speedo housing. With the key on I grounded the wire at the engine to the case but get no light. Voltage between the wire and case with key on is 11.5V. No continuity between oil pressure sender tab and engine case which I think indicates sender may be bad. What could be wrong?
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1965 Beetle
1967 Deluxe Microbus
1969 Squareback

[Eric&Barb]

[shanks]

Thanks Eric&Barb. So I compared the new bulb and holder to another new spare I have and I think they are working correctly. The bulbs themselves have continuity between the contact on the bottom and the bulb housing which tells me the filament is good. The holders have continuity between the tab and contact but not to the housing with no bulb installed. With bulbs installed they have continuity from the tab to the housing which all makes sense to me.

If I understand the circuit correctly, power is supplied to the bulb with the key on from pin 15 on the ignition switch which also feeds the generator light and blinker indicator (they both work). With no oil pressure the switch is closed so the power goes to ground at the engine case completing the circuit and lighting the bulb. With oil pressure the switch is open and no path to ground so no light. Is this correct?

What I don't understand is the ground at the speedo. The speedo housing itself is grounded. How do I check this? I think this is what I see when I get continuity between the tab on the oil pressure bulb holder and the speedo housing. The bulb holders slide into holes in the speedo so that the housing is electrically in contact the housing. So why doesn't this complete the circuit?

It makes sense to me that I should be able to ground the wire at the engine and get a light, which does not happen even though I am reading 11.5V with a DVM between the wire and engine case. If there was a short in the bulb or holder would I still see this voltage?

How would I check for a short at the bulb or housing as suggested?

The sender is bad. I pulled it today and cleaned it with carb cleaner with no luck. I do not have continuity between the tab and the housing as I should. It is a Hella unit made in Mexico. Anything else I can try to get it working? If not, where can I find a decent replacement?

Thanks for the help! I'm slowly becoming less of a novice at electrical.
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1965 Beetle
1967 Deluxe Microbus
1969 Squareback

[Eric&Barb]

Here is an image of the front of the speedometer:

The black plastic thing on the RH side in the image above is the bulb holder for the oil pressure, and gen. The black plastic insulates electrically those two bulbs from the speedometer body, so those ground farther down the wiring system. EG the oil pressure sender grounds that bulb to the engine case, and the other inside the regulator.

Turn signal, dash lights, and the headlight bright are rigged up to ground to the speedometer. So if both of the dash bulbs do not work, might be a speedometer ground problem.
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In Stereo, Where Available!

[Eric&Barb]

Another way to check bulb holder and bulb is to switch the oil pressure and generator bulb/bulb holders. If the problem "no light" switches over to the generator then that bulb and/or bulb holder is the problem. Then you can sort that further out by just switching the bulbs. If problem switches over the bulb is the problem. If the problem does not switch sides, then the bulb holder is the faulty part.
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In Stereo, Where Available!

[Eric&Barb]

Personally we just use OG VW oil pressure switches on our VWs. Have had no problems with those, and easy to find at most any swap meet or local engine rebuilder shop for hardly nothing.

Wondering if perhaps the bulb or bulb holder is shorting out, if that could burn the switch points in the sender....
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In Stereo, Where Available!

[shanks]

Solved!! Thanks again Eric&Barb!

Electrical still confounds me since this solution was weird. First I installed a new oil pressure sender that checked out electrically. Then, I switched the generator and oil pressure bulbs, holders, and attached wires to see if I was having an issue with the speedometer housing. The generator light came on (on the right side) and the oil pressure did not (on the left side). Switched them back to the correct sides and swapped the holders and bulbs, still got a generator light but no oil pressure which indicated to me that it wasn't the bulb or holder. So I pulled the oil pressure holder out and in doing so it touched the ignition switch live wire. Light came on! Put it back in the speedo and I get both generator and oil pressure lights with key on. Started the engine and both go out.
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1965 Beetle
1967 Deluxe Microbus
1969 Squareback

[Eric&Barb]

Good to hear it is all working. Sounds like mayhaps the brass tab the bulb holder touches to might have had some corrosion stopping the electrical flow. You might need to slightly bend that brass tab slightly for a more spring tension contact pressure against the bulb holder.
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In Stereo, Where Available!

[telford dorr]

For what it's worth, the turn signal bulb holder should connect to 12 volts, not ground. That's why it has a screw terminal and a plastic mount (left side in pic below):

Because of these vehicle's age, all the electrical contacts and bulb sockets need a periodic buffing and cleaning.
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'71 panel, now with FI
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