Fuse box surprise, troubleshooting problem with running running/parking lights.

[shuzboomer]

Dear friends,

I have finally got my 86 Targa after a long paint and expensive transmission rebuilt.

The paint project lasted about 2 years and included removing most paint covered bits, stripped to metal and returning back to its prior splendor. The work was done by my buddy, who runs a paint shop (not a Porsche specialist shop), and many weekend wrenching on my end.

The transmission was done by a local Porsche specialist.


At the end of the day the car looks great and drives like a dream..... However, after putting the bits back together I now have number of NEW electrical issues that are making me a complete wreck.

1. Currently both tail lights are out (backup lights are good, break light are good and turn and hazards are good)

2. Front side markers are out ( these are the little lights that sit behind the left and right turn signal lights)

3. The front passenger turn lamp which has two terminals does not light unless the turn signal is engaged ( when you engage turn signal only one of the two terminals get power) The driver side works correctly.

I have checked the fuses and discovered that one of the fuses position 4 if you count from right to left ( looks like a old fuse) responsible for parking light and engine light had wrong wattage 25w and the wire running to it was completely degraded.
I am including the picture of the fuse panel, the fuse in question is the correct wattage, I removed the 25w fuse.

After replacing it with 5 watt the fuse pops as soon as I turn on the parking light (1st click ) when you pull on the light switch.

Both work as usual.

At the end of the day I have no clue is original problem is related to this particular fuse, but I suspect there is a connection.

In addition to my lights issue, both power mirror connections got cut when the doors came off, but I think I will attack this issue next...

Any suggestions on troubleshooting the electrical issue is most welcome.










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[walt]

I would start by cleaning all the fuse contacts and replace all fuses with ceramic. I have fixed more than one electrical issue by doing this.

[dg567]

Also check all of you ground locations, especially the ones near the rear turn signals.

[DRACO A5OG]

That exposed wire to the right of the yellow one looks suspect. I would replace or at minimum clean and heat shrink it.

We need ground to close the circuit when active so makes sure the grounds are clean and tight. Rear assembly is right behind the passenger rear assembly.

[shuzboomer]

That bare wire, I think is the result of the wrong (25w) fuse that i removed. The maual i have says the correct wattage is 5w. I suspect there is a short somewhere that has created enough resistance in the wire to melt the shielding. I am not really sure where to start.

I already ordered ceramic fuses to clean and verify and swap out the rest of the lot. Perhase more gremlins in the works.

Originally Posted by DRACO A5OG

That exposed wire to the right of the yellow one looks suspect. I would replace or at minimum clean and heat shrink it.

We need ground to close the circuit when active so makes sure the grounds are clean and tight. Rear assembly is right behind the passenger rear assembly.

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[walt]

If that is fuse #4, start by pulling your left parking lights and check the socket and wiring. If nothing is obvious you need to work back to the fuse panel.

[adias]

Originally Posted by shuzboomer

2. Front side markers are out ( these are the little lights that sit behind the left and right turn signal lights)

3. The front passenger turn lamp which has two terminals does not light unless the turn signal is engaged ( when you engage turn signal only one of the two terminals get power) The driver side works correctly.

Front side markers are connected to the the front turn signal/position light assemblies. If yours do not work that means a lack of connection, either from the side markers themselves onto the front assemblies, or... internal in the front assemblies.

The front turn signal/position light assemblies have internal pigtail wires connected to the back to supply the side markers. Those connections are extremely short and if the units were disassembled they may not have been reconnected back.

It looks like that your passenger side turn light/position light is misconnected internally. Internally the red/gray wire is connected to the position light (thin wire in the bulb) and the black wire is connected to the turn signal (coiled wire in the bulb); brown wire goes to ground.

The assembly pigtails are: white wire connected to brown ground attaches to the top tab in the back. White wire attached to the gray/red wire attaches to the lower tab in the back of the assembly.

I do not recall where the red/gray (position light) and black (blinker) wires attach in the bulb assembly (top or bottom) but that is easily found by testing which terminals lit the blinker (black wire) and the position light (red/gray wire).

To reattach it all you need to attach the brown red/gray and black wires to the back of teh reflector/bulb and very patiently re-attach the white pigtails to the back of the assembly unit using forceps.

I hope this helps!

[shuzboomer]

Do I need to drop the front bumper to get behind the housing? I recall the passenger side was a crazy reach due to bracket next to the oil cooler.


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[DRACO A5OG]

Use a forsep. You are correct, wire is to darn short. A night mare.

[86 911 Targa]

^^^^^
Here's the fuse panel for our '86.

Gerry

[911tracker85]

glad to see this. just about to attack an issue. when lights are off, turn signals all work. with even the parking lights on, the RR turn signal does not work.

good luck on getting your project back on the road and enjoying it.

[SpyderMike]

Originally Posted by shuzboomer

That bare wire, I think is the result of the wrong (25w) fuse that i removed. The maual i have says the correct wattage is 5w. I suspect there is a short somewhere that has created enough resistance in the wire to melt the shielding. I am not really sure where to start.

Yes, fuses are sized to protect the wiring from such damage in the case of a short. The heat from the current due to the short has melted the insulation - potentially along its entire length. It may have damaged other wires in that loom. To fix it properly, you need to follow that loom all the way to the destination and open it up and replace that wire and any others that are damaged. As an alternate, you can remove that damaged wire from the fuse block and cut/shrink wrap the visible exposed strands...do the same on the other end. Then run a new similarly gauged wire as a replacement the full length. That might work, but there is no guarantee.

[shuzboomer]

I hope I find the short without having to pull the entire loom. Not sure I got the fortitude. Does anybody know what gauge wire is used? Looks like I need to add a few more items to the build list.


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[timmy2]

I’m pretty sure that melted wire should be grey/black and runs through the dash harness to a 6 pin female rubber through body plug that goes to a male plug ending up at the light switch. Porsche used metric wire, closest US AWG wire is 18 or maybe even 20 as the later Carerra harnesses have much smaller wire sizes than the earlier years up to ‘83.

[shuzboomer]

Thanks for all the info.. I got the fuses and wire on order. I suspect next weekend I should have some time to dig in. The only item that is still bothering me is when I look at the fuse chart in my book ( my car never came with a proper cover for the fuses...) is that I see no mention of rear tail lights...

Is there another set of fuses that I am missing or is there another name for them...


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[SpyderMike]

fuse block 2 fuses 5 and 6.

[timmy2]

5 parking lights left and engine compartment light. Front and rear lights from same fuse.

[86 911 Targa]

^^^^^
From my factory manual.

Gerry