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Chrenan · Joined: 15 Jan 2003 Posts: 3903 Location: Canada

Alright, I installed the new oil pressure sender on my engine, fit fine, no issues, looks physically the same as the old one. However, there are no markings on the connection posts, is this normal? How do I figure out which wire to connect to which post?

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1987 951 - M193 Version for Japan

Paul · Posted: Sun May 14, 2006 11:12 am Post subject:

With an ohm meter, of course!

The idiot light is the one that has zero ohms to ground.
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White 87 924S "Ghost"
Silver 98 986 3.6l 320 HP "Frank N Stein"
White 01 986 "Christine"
Polar Silver 02 996TT. "Turbo"
Owned and repaired 924s since 1977
Porsche: It's not driving, it's therapy.

Chrenan · Joined: 15 Jan 2003 Posts: 3903 Location: Canada

Paul, much appreciated, I'll get to work with the multimeter.
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1987 951 - M193 Version for Japan

Chrenan · Joined: 15 Jan 2003 Posts: 3903 Location: Canada

Paul (or any other electrical guru),

Can you explain how to do this test in a little more detail? I seem to be getting ohms out of both posts when I am expecting one of them not to move the needle.
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1987 951 - M193 Version for Japan

Paul · Posted: Wed May 17, 2006 10:10 am Post subject:

The idiot light post should have very low resistance from the post to the case of the sender, since it closes a set of contacts to provide a ground for the idiot light when there is no oil pressure.

The other post should have a higher resistance to ground. What values are you seeing?
_________________
White 87 924S "Ghost"
Silver 98 986 3.6l 320 HP "Frank N Stein"
White 01 986 "Christine"
Polar Silver 02 996TT. "Turbo"
Owned and repaired 924s since 1977
Porsche: It's not driving, it's therapy.

Chrenan · Joined: 15 Jan 2003 Posts: 3903 Location: Canada

OK,

I have the resistance on the multimeter set to 1K ohms, the only setting I have for resistance.

With one lead on a post, and one lead on the case of the sender, I get the same reading regardless of the post:

Just between 0 and 1 on the ohm scale (top red scale). Is it that the 1K ohm scale is not correct for this type of test? Do I need a multimeter with a variety of ohm scales?

Part number on the sender is 047 919 561 which I am pretty sure is correct for the 924.
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1987 951 - M193 Version for Japan

Ozzie · Posted: Wed May 17, 2006 5:56 pm Post subject:

For ten bucks au I can get a digital multimeter at bunnings hardware which would give you more accurate readings.
The resistance for the guage sender may be small (below 100 ohms) and the light would be zero.
Hard to pick up on a 1k ohm scale.
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Porsche 924 1984 (UK import) NA
Its AUTO and its BLACK
Montego Black on black/red
Engineer of Electro/Mechanical Systems Maintenance

Chrenan · Joined: 15 Jan 2003 Posts: 3903 Location: Canada

Hmmm, that's what I thought might be the case. I'll hit Radio Shack at lunch and see if I can find a better ohm meter.
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1987 951 - M193 Version for Japan

Smoothie · Posted: Thu May 18, 2006 1:19 am Post subject:

Another approach would be to hook it up to an air compressor - The light switch contact should show 0 Ohms now with no pressure meaning the switch is closed. If you can apply some pressure through the threaded end, at approx 6-12 psi the switch should open and suddenly send your Ohms reading way up (indicating the switch is open).
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"..it's made in Germany. You know the Germans always make good stuff."

'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox

Chrenan · Joined: 15 Jan 2003 Posts: 3903 Location: Canada

Hey, that's a good idea too!
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1987 951 - M193 Version for Japan

Smoothie · Posted: Thu May 18, 2006 1:58 am Post subject:

Oh there's more

I just had a look at mine with a dental mirror

- mine's marked with a "G" and a "W". These correspond to what's indicated in the wiring diagrams. "W" (or "Wk") gets the blue/black wire that leads to the light. "G" gets the blue/white wire that goes to the gauge. My sender is also round on one side and formed somewhat as if crimped on the other side. If yours has this "crimp" - looking at the connections end with the crimp to your left and the rounded side to your right, the "W" terminal should be at top and the "G" at bottom. Once you get it figured out, mark the gauge terminal with a "G" and the switch terminal with a "Wk" for that OE look.

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"..it's made in Germany. You know the Germans always make good stuff."

'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox

Chrenan · Joined: 15 Jan 2003 Posts: 3903 Location: Canada

Hmmm, I am going to look at mine closely again, but it sounds different to yours. I can't understand why mine wouldn't be marked at all, I mean how annoying is that?
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1987 951 - M193 Version for Japan

Chrenan · Joined: 15 Jan 2003 Posts: 3903 Location: Canada

Smoothie, I was just out in the garage, pulled a piece of masking tape off the sender that came with it. Sure enough, there is crimping on one side, I'll take a pic tommorow, hopefully you can let me know if it looks like yours.
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1987 951 - M193 Version for Japan

Chrenan · Joined: 15 Jan 2003 Posts: 3903 Location: Canada

Smoothie, does this look familiar? Two "crimps" on one side of the sender?

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1987 951 - M193 Version for Japan

Smoothie · Posted: Fri May 19, 2006 12:12 am Post subject:

Yes that's exactly what mine looks like. In that pic, the left terminal should be "W" (warning light) and the right "G" (gauge). If it were marked, you'd see the "W" and "G" stamped into that flat 1/3 moon shaped section of steel that's facing up between the crimp and the terminals.
_________________
"..it's made in Germany. You know the Germans always make good stuff."

'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox