Help! Rear light unit wiring.

[keynsham1]

I am at the part of my rebuild where I need to refit the rear lights of my 1978 911SC. There is a loom on each side plugged into the car with a six pin plug. Each plug has the wiring going into the light unit, which I am OK with. They also each have two pairs of much thinner and stiffer wires. One pair on each side ends in a small pair of spade connectors and the other pair on each side end in a large pair of spade connectors. One wire of each pair is an earth.



I am guessing that on the left side of the car looking forwards, the large spade connectors are for the foglight and the small are for the number (license) plate lights. On the right side of the car I believe them to be for the foglight again as I have one on each side, and for the oil level sender on the oil tank, as there are no other wired for this in the area.

The thinner wires are either a white/yellow/ brown sort of colour except for one which is red. Some have stripes around but the colour is difficult to see.

Can anyone confirm or deny my assumptions?

[timmy2]

Both tail light harnesses are wired identical and can be used on either side of the car.

The small terminals are for the license plate. The large for fog lights.

Your oil level sender should plug in on the other side of the main harness in the engine bay.


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[86 911 Targa]

Originally Posted by keynsham1

I am at the part of my rebuild where I need to refit the rear lights of my 1978 911SC. There is a loom on each side plugged into the car with a six pin plug. Each plug has the wiring going into the light unit, which I am OK with. They also each have two pairs of much thinner and stiffer wires. One pair on each side ends in a small pair of spade connectors and the other pair on each side end in a large pair of spade connectors. One wire of each pair is an earth.



I am guessing that on the left side of the car looking forwards, the large spade connectors are for the foglight and the small are for the number (license) plate lights. On the right side of the car I believe them to be for the foglight again as I have one on each side, and for the oil level sender on the oil tank, as there are no other wired for this in the area.

The thinner wires are either a white/yellow/ brown sort of colour except for one which is red. Some have stripes around but the colour is difficult to see.

Can anyone confirm or deny my assumptions?

Here you go.

[keynsham1]

Thanks guys, that is all clear. One last question though. Where will I see the wires for the oil level sender? I cannot see any wires under the wheel arch. Where does the wire start and what route does it take? It must be there somewhere but I can't see where!

[timmy2]

Take a look under your oil filter at the harness that runs under it. There should be a connector back behind the motor mount I believe.


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[keynsham1]

I am not convinced that the right hand side wiring from the six pin connector only goes to the light unit, fog light, and license plate light. The diagram above shows license plate wiring from both looms but shows the fog light on the right in parallel with the left hand wiring, so its feed is from the left. I have no other wires in my car for the oil level sender unit. The only connector between the inside and outside of the engine bay is the six pin connector so it must be one of these wires. That would suggest that the twin wires with the big spade connectors run both fog lights from the left side and the sender unit from the right side. I wish I could remember! I will do some wiring tests tomorrow and see if I can work it out!

[86 911 Targa]

Originally Posted by keynsham1

I am not convinced that the right hand side wiring from the six pin connector only goes to the light unit, fog light, and license plate light. The diagram above shows license plate wiring from both looms but shows the fog light on the right in parallel with the left hand wiring, so its feed is from the left. I have no other wires in my car for the oil level sender unit. The only connector between the inside and outside of the engine bay is the six pin connector so it must be one of these wires. That would suggest that the twin wires with the big spade connectors run both fog lights from the left side and the sender unit from the right side. I wish I could remember! I will do some wiring tests tomorrow and see if I can work it out!

The CKT I sent you is from our '86.

[targa80]

Here is a section of the USA 78 schematic showing G12 ( oil level sending unit) attached to T6a ( right side engine compartment connector). The sending unit wire is white with a green stripe. G13 is the oil level gauge. the entire 78 schematic is available from our host in PDF form on the catalog page on the left side under elect schematics.

[targa80]

Looking at the 78 USA schematics there is no call out for any fog lights (front or rear). Unless there is a different wiring scheme for ROW car.

[keynsham1]

ROW cars in the UK had rear fog lights, one added on a bracket on each side. It wasn't a legal requirement until 1980 and so as my car is a 1978 I don't plan to refit them. I think they look like an afterthought!

Thanks everyone for your inputs. I think I now know what is what!

[timmy2]

Ok, my mistake I was thinking of an earlier year car while I was away from my shop.
I am looking at a set of rear lamp harnesses as well as the through the body harness. And associated prints.
On your right rear light wiring harness the large spades are for the oil level switch the lighter color is ground the darker reddish brown one is to the sender. It comes out on the pin just to the left of the alignment tab as you face the plug. That is the corresponding pin for the green white wire to your gauge. The other thinner wires go to the right side license lamp.
In the left side the larger terminals are indeed for the fog lamp on ROW cars. Normally tied off and tucked away on US cars.

Hope that helps


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