Oil Level Gauge Wire Missing

[Smoove1010]

I think I know why my oil level gauge isn't working on my 87 Carrera cabriolet - there's a wire missing! (pic below)

According to Bentley there should be a white wire connected to that open spade connector on the back of the gauge; in many photos throughout the forum a green/wht one is connected but it also seems that this varied from year to year. I'm going to be searching for any dangling wire behind the dash - my question is this: Can anyone advise on the routing of that wire, and where I might concentrate my search? I'm assuming it comes up through a penetration in that area under the cowl, but any advice on where that is would be appreciated.

That spade connector looks dusty and oxidized like nothing's been connected to it for quite some time. I'm finding one thing after another like this in my car - wires left dangling or connected to the wrong things... I made a ton of progress fixing things like this the past few months, but some day I'd like to meet whomever worked on this car's wiring and take his tools away.

Thanks in advance!
GK

[bkreigsr]

Have you tried to run a jumper wire outside the car to the sender in the rr qtr. panel, just to see if you're on the right track?
I would assume that anything with red is to a power source, so the missing wire must be from the sender? (red w black tracer=power)
Does the gauge power up and light?
Bill K

[Smoove1010]

Originally Posted by bkreigsr

Have you tried to run a jumper wire outside the car to the sender in the rr qtr. panel, just to see if you're on the right track?
I would assume that anything with red is to a power source, so the missing wire must be from the sender? (red w black tracer=power)
Does the gauge power up and light?
Bill K

Hi Bill - the gauge works in every other respect (gas gauge, low-fuel light, illumination). The Bentley schematic says the missing wire should be white (clip below.) The schematic shows that the hot wire (red/blk) goes to the gauge and the missing wire goes to the sender which progressively grounds the circuit causing the level indicator to increase, so a good test would be to jumper the bare spade to ground which should peg the meter.

I'm certain that there's a dangling wire under there somewhere, I'm just looking for a clue as to where it's supposed to emerge.

[Cloggie]

I dug up this thread while putting together my '89.

According to all manuals including the factory wiring manual for the '89, the sender wires do not go through the plug on the passenger side engine compartment that feeds the passenger side tail light assembly which was the case prior to 1989 (and likely 1987 forward)

On the 1978 wiring diagram, it shows the level sender going through plug T6a which is the 6 pin passenger side tail light feed.

In the '89, all 6 wires for that plug are consumed with the signal light, stop light, parking light and the rear fog light.

I cannot find any suitably sized hole in the engine compartment on that side that would let it through - and I have the wires and the gauge does work properly, just no place to thread them on my '89.

It's different than earlier cars...anyone have any insight?

Thanks!

D.

[timmy2]

Isn’t there a 7th pin on the 89 tail lights? Dead center.

[Cloggie]

Originally Posted by timmy2

Isn’t there a 7th pin on the 89 tail lights? Dead center.

.....you are right, but as shown in the factory wiring diagram for the '89, all 7 (I stand corrected) pins of that socket are used for the lighting



If I look at the part of the wiring for the oil level sensor, it does not show any connector at all (and is not on the list of connectors), which is consistent with what I find in the car.

There is a wiring reference on the car which is not explained in the forward - NR. 1/61 which may be a locator but which does not match up with the other locator information which is well defined.



I took about a million photos of the car before it was disassembled, but not one of the oil tank or its gauge...and can't find one on the web.

I have found one photo that shows the wire coming from the top of the tank, clipped to the tank flange, but no visibility as to where it pierces the body.

I am wondering if it goes through the large rubber seal between the oil tank/oil filter console and the body, but a part number check shows the same part from the mid-80's 911 right up to the 89, and knowing the Porsche neurosis with supersession, would have expected a different suffix. 911-XXX-YYY-02 or something like that.

It is a mystery and I am reluctant to drill another hole through my newly painted chassis.

Thanks!

D.

[timmy2]

Not all that familiar with 84-89.
Is there a sheathed white wire (or even a connector) coming out of the through body harness near the passenger taillight connector?
They did that in 69 for some reason, maybe a 30 years later anniversary mod?
Lol,

[Cloggie]

Originally Posted by timmy2

Not all that familiar with 84-89.
Is there a sheathed white wire (or even a connector) coming out of the through body harness near the passenger taillight connector?
They did that in 69 for some reason, maybe a 30 years later anniversary mod?
Lol,

The gauge wiring (which I checked and which indeed is correctly connected to the gauge) comes out of the wiring harness about under the oil filter. \

The harness then continues to the lighting plug at the very back of the engine compartment - no other wires exit at that point.

The gauge wires are properly sheathed with the white heat protector....just they exit the harness into the engine compartment.

....a mystery....but thanks for your help!

I might just poke a hole through the oil tank rubber fitting and run it through there, seems like the least offensive spot unless I hear to the contrary or find a pic of where it is "supposed" to be run.

D.

[jgurnari]

Did you figure it out?

'85 911. I had changed my oil and had cleaned up around the oil filter and had the 6 pins out of the rear right tail light connector. Seems I got the wires back in, in the correct order, all lights are working properly.

The problem Im having, the oil gauge is pining up when I turn on my lights. with lights off, the gauge is at the bottom. Issue scenarios Ive read.. sender gasket?..sender itself, (sender worked prior to oil change) or something else?

I thought I may have misplaced 2 wires G/W and the Double white wires, when I switched their positions in the connector, right side license plate light did'nt work and the gauge pinned up when I turned the key on instead of pinning up when turning on the lights so I switched back..Im back to pinning when lights are turned on and plate light works correctly.

The G/W wire can only be the only gauge level, I tested and do NOT get power to it,
I assume I should be getting power to that wire?

The back of my gauge is similar to yours...did you find a wire that fell off that open spade?...i have an open spade as well...didnt couldnt find a loose wire behind in the dash.

What can I do to test every for the issue?

Originally Posted by Smoove1010

I think I know why my oil level gauge isn't working on my 87 Carrera cabriolet - there's a wire missing! (pic below)

According to Bentley there should be a white wire connected to that open spade connector on the back of the gauge; in many photos throughout the forum a green/wht one is connected but it also seems that this varied from year to year. I'm going to be searching for any dangling wire behind the dash - my question is this: Can anyone advise on the routing of that wire, and where I might concentrate my search? I'm assuming it comes up through a penetration in that area under the cowl, but any advice on where that is would be appreciated.

That spade connector looks dusty and oxidized like nothing's been connected to it for quite some time. I'm finding one thing after another like this in my car - wires left dangling or connected to the wrong things... I made a ton of progress fixing things like this the past few months, but some day I'd like to meet whomever worked on this car's wiring and take his tools away.

Thanks in advance!
GK