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Weird electrical/bulb issues (Read 323 times)
slinger569
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Weird electrical/bulb issues
Sep 8th, 2019 at 7:08pm
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So last month I was working on the car and had pulled the right tail light out and had to replace a few bulbs. I also swapped out my fog lights (H4) at the same time. When I was testing to make sure everything was working correctly, I’m getting a fast blink out of the right side directional but normal speed on the left. I went back in and checked all the bulbs and made sure I put in the bulb (7506), tail light bulb (5007) and front directional (7528)..
To top things off my right fog light stopped working but the left light works fine. I clearly have something going on on the right side.
Brake lights work on both sides.
Directional work on both sides BUT right directional is fast, left side in normal.
Fog light works on the left side but not on the right side. I moved the fog light from left to the right but it still doesn’t work. I put a test light on the wiring for the right and it’s getting power.

I have been at this all day and can’t figure it it.
I checked all my fuses and the only thing that keeps happening is I blow fuse #11 every time I put one in.  Which I believe is the fuse for the cigarette lighter and the interior lights ..
I have pulled and tested every single fuse in the box. Only fuse 11 gives me a problem.
  

Dave
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anchor
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Re: Weird electrical/bulb issues
Reply #1 - Sep 8th, 2019 at 11:58pm
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WS Manual Vol. 5 shows fuse 11 as 15 amps.

The rear fog lamps on 89 Turbo, sort of surprised me and there is a cutoff ckt. In conjunction with them but it is Japan only.
Sounds like a bolted ground on a hot wire, have you checked relay G11 by part number?

Maybe the contacts are fried and something like that might be in the register somehow.
« Last Edit: Sep 9th, 2019 at 6:27am by anchor »  

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Dave W
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Re: Weird electrical/bulb issues
Reply #2 - Sep 9th, 2019 at 5:33pm
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The rear taillight housing contacts for the bulbs can get corroded.  Remove the bulb and see how clean the contact tabs are.  It's just like a bad ground; it causes odd problems.  For blinkers, it will be fast blinking just like a bulb is burnt out.
  

Dave - black 84 no longer exists. Sad 83 self destructed. All better now. Smiley
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slinger569
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Re: Weird electrical/bulb issues
Reply #3 - Sep 9th, 2019 at 10:20pm
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Thanks guys. I’ll check both those things tomorrow and let you know how it goes. I think I have a spare relay somewhere to swap out.
  

Dave
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OhioTom
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Re: Weird electrical/bulb issues
Reply #4 - Sep 11th, 2019 at 8:14pm
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I vote an poor ground on the tail light assembly.

Fog light sounds like a ground issue as well.
Good bulb, power present, but no illumination?... Ground..
  

Tom Simpson&&VW/Porsche freak.
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slinger569
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Re: Weird electrical/bulb issues
Reply #5 - Sep 12th, 2019 at 1:34pm
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Sorry, I haven't had time to look at this yet, maybe this weekend. But my question is, if the fog light issue is related to a bad ground wouldn't I have a problem with the other light as well? Just wondering. Do the both lead back to the same grounding spot or do they ground to the body in separate spots?

I did find something on Clarks about TSB-98902 from Porsche. See attached. Looks like this might have something to do with Fuse 11 blowing. Apparently the Technical Bulletin from said the red glove box wire can touch metal and ground blowing the fuse..


  

fuse_11.jpg ( 78 KB | 9 Downloads )
fuse_11.jpg

Dave
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anchor
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Re: Weird electrical/bulb issues
Reply #6 - Sep 12th, 2019 at 6:28pm
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Bolted hot to ground sounds , about correct.
The flasher relay should make them all ( blinker) sockets unison with the red emergency button , if not try swapping out relay G4.
Just tape the red ( glove box conductor) at or on copper exposed insulation with electrical tape if you find abrasion in a exposed position.

The stalk on the steering column could be one of the problems with the blinkers. One post about 6 months ago is on the search, they are evidently hard to find but repairable.

The grounds are right hand , left hand( MP IV MP V) for the fogs, I believe from looking at the diagrams. They would seem to be on the frame just behind the headlights so premier place for build up corrosive goop.
  

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slinger569
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Re: Weird electrical/bulb issues
Reply #7 - Sep 16th, 2019 at 11:51am
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Good morning guys

So here's an update.

I found the issue for the blown #11 fuse. It was in fact from the Glove box wiring coming in contact with the body. I did as the Porsche Service Bulletin suggested and bent the wiring contacts downward away from the body. Issue resolved.

I then went for the fast directional on the passenger side. After further inspection I notice the passenger front side marker bulb was burnt out -  #5008. When I pulled the bulb there was a tiny bit of corrosion so I lightly sanded the connector and added some bulb grease. (decided to do both sides - seeing as I already had the other bulb). Side markers both work but still have fast direction on the passenger side, but not on the drivers side. hmmm.. Turned on the headlights and everything lights up (parking lights, brake lights, side markers, head lights, front directionals)... So I decided to move onto the fog lights and come back to this... (Sorry Anchor, I didn't have a relay for G4. I'll try to pick one up.)

Fog light - So first step I did was try another bulb. Of course I knew the bulb in there was good, but step-by-step right... still not working. I also swapped out Relay G11 just for kicks - no change. So I got my test light out and it showed good power and ground at the fog light... But I saw some corrosion on the negative side connector so I replaced it, connected back up, but still not working.. So I went right to running a negative wire right to the battery, bingo!, fog light came on. Now we're getting some where.. As you guys said, it's a ground problem.. So then I went to the grounding bolt behind the headlight, disconnected, sanded the grounding spot on the frame, lightly sanded the wire connector and hooked everything back up.. Should be good right? NOPE... So then I ran the ground by-pass wire I had earlier and ran that right to the grounding spot.. Still nothing.. But now the fog light doesn't work, the right rear parking light, right rear side marker & right front side marker don't work now... Ugggg... So then I went through every single fuse, one by one, and they are all good...
Oh to add insult to injury, my Airbag light is now on...  Roll Eyes

After 2+ hours I had to walk away before my Irish temper got the better of me... (insert exploding head here)

I'm ready to pull the front bumper cover and trace the fog light wires but I'm thinking that might be a bit drastic.

What do you guys think?

  

Dave
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Dave W
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Re: Weird electrical/bulb issues
Reply #8 - Sep 16th, 2019 at 4:47pm
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It's starting to sound like a broken wire but that's usually a problem on the headlight harness where it moves around with the headlight frame.
  

Dave - black 84 no longer exists. Sad 83 self destructed. All better now. Smiley
... Let's go hit some twisty roads! ...
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slinger569
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Re: Weird electrical/bulb issues
Reply #9 - Sep 16th, 2019 at 6:21pm
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Thanks Dave. That’s what I was thinking too. I guess the best way to determine that is to pull off the bumper cover. I guess I have my project for next weekend.
  

Dave
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