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Looking for a pic: Back of the fuse panel 88 S4

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Old 07-08-2008, 12:50 PM
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michaelathome
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Default Looking for a pic: Back of the fuse panel 88 S4

Title about sums it up,

Looking for a pic of the back of the fuse panel while in the car. Specifically I am trying to diagnose problems with my passenger side high beem so I am focused on fuses 31, 32, 38 and 39, wiring from the relay and to what I think is the connector M (green) at the bottom of the panel.

Michael
Old 07-08-2008, 01:26 PM
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Alan
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I don't think a picture is going to help you... all the wires are grey and difficult to see. More importantly has anyone messed with it? Do you have any non-grey wires except for the brown ground wires and a few heavy duty red wires to fuses (in/out)?

Maybe post a picture of what it looks like...?

Did you change anything? - did you replace a fuse block by chance?

Test that the top of fuse 31 is directly connected to the top of fuse 32? (0 ohms).


The bottom of fuse 32 should connect directly to the bulb connector for the high beam passenger side in the fender (check) the white wire.

You need to test - not look (things that look good can easily be bad...)

Alan
Old 07-08-2008, 02:36 PM
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michaelathome
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Thanks for the reply Alan.

I have had the problem since I got the car. I have let it slide for several years and just started looking into things.

First thing that I had noticed is headlamp operation. The lights will not raise, to be expected, BUT will not lower without key in the on position. I was under the impression that they should lower with or without key on. Assuming this was in fact not correct operation leads me to believe that something had been changed.

Now to the problem, driver side high beam works, passenger side high beem does not. Driver and passenger side low beams function as normal.

Here is where it gets interesting, pulled fuses 38 and 39 and as expected low beam operation ceases. Pulled fuses 31 and 32 and driver side high beem still functions. Started trying to diagnose at the green harness block but had to call it a night as it was getting late.

So in summary, someone has bypassed fuse 31 and 32 to get the high beems to function yet whatever bypass was used has failed and I have no operation of passenger side high.

There are no visible added in wires or spliced in wires on the fuse/relay block or behind the block which leaves me with 2 options.

1. Changes were made elsewere
2. Changes were made on/behind the panel using the factory grey wires. (why I was looking for a picture)

Another thing that I noticed is that there are 3 wires on the back of 39, one lower wire, assuming thats ground, and 1 to relay and one to green harness block. There is only 1 wire on fuse 38 (lower wire).

I had the WSM wiring diags out and will try to take a look again tonight when I get time.

Michael
Old 07-08-2008, 03:05 PM
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Tom. M
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Here's the best image I can find .... Sorry..couldn't resist....that's what it looks like to me

Old 07-08-2008, 03:17 PM
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Alan
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Originally Posted by michaelathome
First thing that I had noticed is headlamp operation. The lights will not raise, to be expected, BUT will not lower without key in the on position. Michael
This is correct operation. The reason is so you can leave the pods up (but not on) for cleaning... else you'd have to clean them with the headlights on...

The fuses connect together at the top inside the fuse block (or should) - its not obvious... (and not all years are the same...).

Did you have higher than spec bulbs installed (80/100W maybe?)

Do you have any additional wires at the jump post - should only be 3 red wires... its possible someone has added relays for direct drive (off just one high beam fuse...) if so you need to trace the wires to find where... the jump post is the most common attachment point for this.

Are you sure neither fuse 31/32 makes any difference to either high beams? it has to get a high beam signal from somewhere - even for a relay...

The connection to the fuses 38/39 sounds normal.

Alan
Old 07-08-2008, 03:35 PM
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Hey Michael,
One thing that you can do is look for jumper wires added to your block to power aftermarket accessories such as built-in phones (remember those) which many of our cars got, radar equip. and stereo equip. Some of the aftermarket installers would slip a little copper spade jumper into a fuse slot to get the power that they needed for their install.
I found an abandoned one that was causing intermittent connection with my pass. footwell light circuit. The fuse base is now loose/damaged due to this jumper, but I was able to fix it enough to get solid contact with the fuse once again.
If you come across one, figure out if it's in use, and check the stability of the fuse base that it's jumped to. Personally, I'd try to get rid of all of them and use inline jumpers, because those little spade jumpers aren't worth a sh*t.
Just a thought.
Old 07-08-2008, 03:42 PM
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Originally Posted by michaelathome
Title about sums it up,

Looking for a pic of the back of the fuse panel while in the car.
Originally Posted by Tom. M
Here's the best image I can find .... Sorry..couldn't resist....that's what it looks like to me


Yup that's about right!

Michael, this is from my '89 S4. Good luck!
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Old 07-08-2008, 03:53 PM
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michaelathome
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Jeff, can you email me a larger version of that image? That should work as long as it is stock, no changes? email to michaelji at hotmail.com pretty please
Old 07-08-2008, 04:01 PM
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Originally Posted by Alan
This is correct operation. The reason is so you can leave the pods up (but not on) for cleaning... else you'd have to clean them with the headlights on..
Guessing that not all 928s are like this then and it likely changed by year.

Originally Posted by Alan
Did you have higher than spec bulbs installed (80/100W maybe?)
Not at this point. At least I never have.

Originally Posted by Alan
Do you have any additional wires at the jump post - should only be 3 red wires... its possible someone has added relays for direct drive (off just one high beam fuse...) if so you need to trace the wires to find where... the jump post is the most common attachment point for this.
I will look.

Originally Posted by Alan
Are you sure neither fuse 31/32 makes any difference to either high beams? it has to get a high beam signal from somewhere - even for a relay.
I am pretty sure. Will double check.
Old 07-08-2008, 04:12 PM
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Alan
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'87 - '89 are similar but not wired exactly the same - an '87 is the closest to an '88, but the headlight wiring is the same across '87-'89.

Investigate for extra relays and look for an extra connection to the headlight relay high beam input or outputs (maybe chained off somewhere else they go - since thats much easier to do...).

Guessing that not all 928s are like this then and it likely changed by year.
Maybe not for all years - but it is true for S4+ with the correct relay... I have heard of some cars behaving differently - so some relay versions may not work correctly.

I'm certain this is the intended S4 behaviour - Porsche went far out of their way to make it work like this...

Alan
Old 07-08-2008, 04:15 PM
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Originally Posted by heyjeffm

Yup that's about right!

Michael, this is from my '89 S4. Good luck!
The person in the factory wiring this thing up with mostly grey wire must have been the highest paid worker in the plant.
Old 07-08-2008, 04:23 PM
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Originally Posted by michaelathome
Jeff, can you email me a larger version of that image? That should work as long as it is stock, no changes? email to michaelji at hotmail.com pretty please
email sent!
Old 07-08-2008, 04:55 PM
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michaelathome
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Thanks Jeff,

For those interested I have posted the larger version here:

http://gallery.rennlist.com/gallery/...6240040?full=1

Hope you don't mind Jeff

Michael
Old 07-08-2008, 05:49 PM
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I don't mind... BUT to be accurate you should include with the photo that it is from an '89 not an '88. Just in case there were any significant differences between those model years. Let's not confuse anyone who is trying to understand that tangled web of wires anymore than they already are!

And it might also be a good idea to let any viewers know that the reason I had to remove that fuse panel was to fix a wire which had overheated and melted its insulation coating. That damaged wire is visible about midway down on the r/h side of the photo.



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