Porsche Enthusiasts Club Forum

I am struggling with the wiring for my 3rd brake light on MY88 S4.
I fitted the same 3rd Brake light onto my previous MY89 928 S4 using the correct wire in the existing loom which is the bottom black wire in the multi-socket in the roof above the lining. I have wired up to the same wire in MY88 S4 and the brake light doesn't light up ???
Checking the wiring diagrams for both years it seems it should work OK so any idea's? I'm not the worlds best electrician but have tried to check the terminals & earths etc. with my multi-meter & all seems OK

Thanks

Steve

"A Porsche 928 gives you a sense of being someone special, you drive as if you have to live up to the car. Your temper improves miraculously; if anyone overtakes you or cuts you up, it's because you have given them permission to do so, or because they are suicidal, not because their cars are more powerful or their driving more skillful! "

All sorted now witht he help of the 928.org guys. Paul Smith & Paul Lacey

Here's Paul Lacey's suggestion which I followed & worked a treat :-
--------------------------------------------------------------------------------------------------------------------------------------------------------
Take out the left rear light assembly, cut the outer sheath back a bit and look for Black/Red wire. This is power supply to brake light. Use a scotchlock connector or strip some sheathing back with a sharp knife and solder a new wire onto the Black/Red. Poke a little hole in the rubber grommet through which the lamp assembly securing post goes (the thing with the big alloy nut on the inside)

Tape up your Black/Red wiring / solder joint, feed new wire through the hole in the rubber grommet (not the mounting hole or it will get worn through) and replace the lamp assembly.

Run the new wire up the left side of the tailgate opening under the rubber weather seal to the top right corner. You will see there is a plastic guide up there through which the wiring passes from under the headlining to the tailgate. The idea is to route your new wire through that with the existing, it's fidly but I've done it a few times.

Remove the rear sun shades (four screws) then remove the top lining from the tailgate - the part with the interior light in it. It pops off but can be tricky, be patient and use a large flat blade screwdriver if required.

You now have access to your new wire and also the earth for the interior light (Black/White) and these are used for your third brake light. I use a strip of red LED type which has adhesive feet to stick on the very top of the rear screen.

This will not cause any type of bulb warning.

Hope it helps

Paul Lacey
----------------------------------------------------------------------------------------------------------------------------------------------------------------

Works a treat!
Thanks guys

Steve

.., good to read you got the wiring sorted, I fitted a seven led light to mine around ten years ago, and spliced directly into the offside rear stoplight, and an earth nearby. Did,nt have any issues with spurious lights coming on etc, but mines an 80 MY.
Incidentally what lamp did you use ? the one I chose fits exactly between the two rear visors.
Below is a pic

Ken.,


http://imageshack.us/photo/my-images/15/dscf2069j.jpg/

Mine is the official Porsche 928 & 944 part.

See below

Outstanding fix Steve!

Do you tthink there's an error in the wirng diagrams? I certainly struggled to reconcile the MY88 chart with the connector in your hatch - baffling.

Anyway glad all sorted so will have no excuse if I run into back of you on a future convoy!

Hi Adrian

I do think the wiring diagrams do not fully relate to the cars we have for the years they are.
The reason I didn't take for granted the replies back in May was for that very reason - all the ROW wiring diagrams for MY88, MY89 MY90 & MY91 do not have the 3rd brake light wire showing to that Multi-block and yet all the people I know with 3rdbrake lightss fitted from that period including my last 928 all have used that wire & it fully functional.

I can't answer it in any other way. Yes, the wiring diagrams are wrong for UK cars as some have said that the 3rd Brake light wire was there for USA & UK cars from early on.

It is a strange quirk.

But glad to get it working even if it is via a different method than planned.

Next I am trying to get my remote hatch to unlock the tailgate as all the mechanisms seems to work but the striker isn't being contacted by the cam & have tried the more simple fixes.

The other fix I need to look at is my bonnet cable needs adjusting & my Power steering seems to be leaking somewhere - am guessing the filler bottle but will start there.

Will get to the trans beldon cable issue looked at again leading to half term. Have had to change out my Power steering pump belt again as it had worn away to not functional in 9 months. Need to replace all the belt pulleys when |I turn round the harmonic balancer so it reads TDC in the right position.

But she is going well & has the new Phillips headlight bulbs in her and she can see the road brilliantly. Hope she passes her MOT later this month.

Cheers
Steve

PS leaks are hard to pinpoint as the stuff drips everywhere!

I've never know a reservoir leak, though the supply and return lines where they clamp to the reservoir get soft and greasy with age.

More likely leak candidates are the rack boots, and the high pressure line which is prone to pinhole leak.

Hi Adrian

I moved my Reservoir bottle the other week when doing the timing belt tension check so guess I moved the crimped hose joints at the bottom of the bottle. Thats where they seem to be starting to get wet anyway so will start there and move down the system lines to the power steering rack.

Cheers
Steve

Hi Steve

That fluid causes a LOT of engine fires as its extremely inflammable.....it gets onto hot exhaust and poof, you have a fire, so fix it fast....

All the best Brett

Brett is dead right to warn of fire danger, but the cause is almost invariably leak from high pressure hose which is positioned right next to hot exhaust manifold, and any leak sprays fluid over this.

The lines to the reservoir are just clamped on so moving them shouldn't cause a problem - they will weep but the fluid is under no/low pressure there so will just drip down the lines to the belly pan or ground if pan is not on.

The fact that it drips and follows surfaces makes pinpointing leak harder, but as start I would clean everything up as best as you can, then do some low speed full lock turns and then run hands along lines/inspect to see if leak more obvious. The biggest danger is leak from high pressure line where it comes up into engine bay then loops over to head down to pump, so at least this section is easy to access and touch to assess for leaks.

Steve, I forgot to thank you for the photos of your steering hoses you sent me. It helped me fix mine a few weeks ago. The only reason mine never caught fire was the steering fluid had never been changed, you could stand a spoon up in it.

Lee

Glad I could be of some help.

Brett, Adrian. Appreciate the advise & caution. Been here before so fully understand the situation & its good to warn the forum or remind them. My previous 928, MY89, developed the classic pin hole inside the high pressure sleeve that sits on the curved pipe up over the strut area which loops over. This area is high pressure & extremely dangerous as its right by the exhaust manifold. The sleeve is there precisely for this reason & to shield the pipe from the excess heat in that area which invariably causes the fracture in the first place. I managed a quick fix with a visit to Pyrtek with the pipe & they fitted me with a new hose & fittings at the correct angle for the banjo bolts.

With regards to my current leak, iobviousvioous due to a puddle of ATF on the garage floor right below the reservoir. The reservoir was half empty. So have tightened the hose clamps under the bottle & we will see if it still leaks. However, even with this confined & easy to see leak away from the engine, as in your comments, this still has sprayed the underneath of the engine & down on the exhausts & the under carriage so its still a potential threat & needs sorting out immediately.

Will let you know if I have managed to cure it later today. Am going to degrease all the pipes & under the engine bay etc then steam clean later today so at least I will be able to see any more potential risks.

Thanks again

Steve

Well had a successful afternoon - so far. Removed the reservoir and jostled it so I could tighten up all the jubilee clips for the flexible pipes. Then, sprayed degreaser all down the pipes, & while I was at it all under the engine bay, struts, chassis legs etc & anything else I could see.

Left it for 30 mins then carefully got the power washer in the engine bay & cleaned the power steering pipes, reservoir & pretty much anywhere that I could see some grime. Then moved underneath the car, got it up on jacks, and let loose.

Wow, what a result, the engine is now aluminium colour at the front & underneath. All the pulleys, crimps, bolts etc. look almost new. Engine looks amazing underneath. Spent an hour or so then cleaning all the undercarriage with more degreaser & more power washing. Result, a very clean car underneath! Noted last night no more ATF fluid underneath the car so think I may have cured the leak. But,, this morning I made sure both jubilee clips were nice & tiagaingian since I could now get to the 2nd hidden one. So, hopefully job sorted & at least if there is a small leak I can easily see it on the nice newly cleaned pipework.

Cheers
Steve