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Driver's side front fog light only partially illuminated.

Snap Oversteer
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Snap Oversteer Member

Snap Oversteer

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Posted (edited)

Hi folks. Weird issue -- I did a forum search and came up empty.

Here's the issue: all fog lights work, but the driver's side front fog only partially illuminates. It looks like only a portion of the filament is lit. All other lights, including the right front and left rear fogs work fine.

 

Here's what I've done to troubleshoot:

Replaced bulb (twice, just to be sure)

Cleaned all contacts with contact cleaner

Replaced headlight switch

 

Vehicle: 2000 986 base

 

Thanks in advance for any help!

Edited by Snap Oversteer
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JFP in PA Member

JFP in PA

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Welcome to RennTech.

 

Check the grounds on the light in question.

JFP, I just checked GP2 and GP3 per Bentley Manual. Both are secure and wires look good. I'm running out of ideas...

 

 

Yes, but did you check them with a multimeter for continuity and resistance?

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Snap Oversteer Member

Snap Oversteer

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Welcome to RennTech.

 

Check the grounds on the light in question.

JFP, I just checked GP2 and GP3 per Bentley Manual. Both are secure and wires look good. I'm running out of ideas...

 

 

Yes, but did you check them with a multimeter for continuity and resistance?

 

Ho boy. I'll have to go back and dig up my Auto Electrics 101 notes and figure out how to do that! I'll let you know what I come up with when I get a clue...

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Snap Oversteer Member

Snap Oversteer

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Welcome to RennTech.

 

Check the grounds on the light in question.

JFP, I just checked GP2 and GP3 per Bentley Manual. Both are secure and wires look good. I'm running out of ideas...

 

 

Yes, but did you check them with a multimeter for continuity and resistance?

 

 

OK, that was easier than I thought. So both circuits involved had a nominal amount of resistance, around 3 ohms. I'm thinking that indicates we have continuity. I'm wondering now if there's a bad connector at the headlamp. The connector at the foglight looks good. I guess I should check for continuity between the headlight connector and fog connector next?

Edited by Snap Oversteer
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JFP in PA Member

JFP in PA

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Welcome to RennTech.

 

Check the grounds on the light in question.

JFP, I just checked GP2 and GP3 per Bentley Manual. Both are secure and wires look good. I'm running out of ideas...

 

 

Yes, but did you check them with a multimeter for continuity and resistance?

 

 

OK, that was easier than I thought. So both circuits involved had a nominal amount of resistance, around 3 ohms. I'm thinking that indicates we have continuity. I'm wondering now if there's a bad connector at the headlamp. The connector at the foglight looks good. I guess I should check for continuity between the headlight connector and fog connector next?

 

 

Three ohms strikes me as higher than I would expect.

 

Yes, I would also check the headlight connector as well.

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Snap Oversteer Member

Snap Oversteer

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Update: finally had time to check the interior wiring of the headlamp assembly. Instead of just checking for continuity, I wanted to make sure the wires and connectors to the fog lamp were actually transmitting the current without some sort of loss/resistance along the way. So here's what I did: I built a couple of test leads from some copper wire and alligator clips. I hooked one end of each lead to a 9V battery and the other end to the ground post on the headlamp assembly and the positive post for the fog lamp. Then I pulled the fog lamp connector and checked the voltages.

 

Result: exactly 9V at the fog lamp connector. So it looks like the wiring in the headlamp assembly is not the problem.

 

I guess my next step would be to see if the voltage to the headlamp assembly is within spec, so I'm thinking I'll remove the headlamp assembly, crank the engine, and check the voltages at the connector. Question: anyone know what the voltage should be? I'm assuming it would be around 13V with the engine running, but don't want to assume.

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JFP in PA Member

JFP in PA

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Update: finally had time to check the interior wiring of the headlamp assembly. Instead of just checking for continuity, I wanted to make sure the wires and connectors to the fog lamp were actually transmitting the current without some sort of loss/resistance along the way. So here's what I did: I built a couple of test leads from some copper wire and alligator clips. I hooked one end of each lead to a 9V battery and the other end to the ground post on the headlamp assembly and the positive post for the fog lamp. Then I pulled the fog lamp connector and checked the voltages.

 

Result: exactly 9V at the fog lamp connector. So it looks like the wiring in the headlamp assembly is not the problem.

 

I guess my next step would be to see if the voltage to the headlamp assembly is within spec, so I'm thinking I'll remove the headlamp assembly, crank the engine, and check the voltages at the connector. Question: anyone know what the voltage should be? I'm assuming it would be around 13V with the engine running, but don't want to assume.

 

Should be battery voltage.

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Snap Oversteer Member

Snap Oversteer

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Okay, I think I'm starting to get to the bottom of this issue. All the voltages in the female connector inside the fender checked good. I wasn't sure where to go next, so I replaced the headlight unit, had a beer (to improve my creative abilities), and tried the headlights/fogs again. The left side fog didn't illuminate at all! I pushed inward on the headlight unit a bit, and the fog came on, partly illuminated. My hunch is that the female socket is worn and we're not getting a good connection. I'll mess around with it tonight and see if I can maybe pinch the connector a bit and improve the contact.


 


In other news, I've now noticed a distinct rattle coming from the right rear over rough pavement when the car is warmed up. Guess I'll be replacing the trailing arms soon...


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Snap Oversteer Member

Snap Oversteer

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See my post on this issue.  It was a loose connector in the bracket...Took it out and plugged directly into the headlight assembly (There is enough slack in the wire to do so) and works like a charm.

 

Thanks! I'll give that a try. I just ordered a new connector from Pelican #999-650-150-40 ($9.75). Hoping the wiring to the connector is some sort of simple plug-in type arrangement that won't require a lot of soldering, but I'm probably wrong.

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SteelStroke Member

SteelStroke

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See my post on this issue.  It was a loose connector in the bracket...Took it out and plugged directly into the headlight assembly (There is enough slack in the wire to do so) and works like a charm.

 

Thanks! I'll give that a try. I just ordered a new connector from Pelican #999-650-150-40 ($9.75). Hoping the wiring to the connector is some sort of simple plug-in type arrangement that won't require a lot of soldering, but I'm probably wrong.

 

I have only been a 1st time Porsche owner for 32 days now.  This site is INVALUABLE!  Learn more and more everyday!  Consider a contribution.  This site has saved me some $$!

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Snap Oversteer Member

Snap Oversteer

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See my post on this issue.  It was a loose connector in the bracket...Took it out and plugged directly into the headlight assembly (There is enough slack in the wire to do so) and works like a charm.

 

Thanks! I'll give that a try. I just ordered a new connector from Pelican #999-650-150-40 ($9.75). Hoping the wiring to the connector is some sort of simple plug-in type arrangement that won't require a lot of soldering, but I'm probably wrong.

 

I have only been a 1st time Porsche owner for 32 days now.  This site is INVALUABLE!  Learn more and more everyday!  Consider a contribution.  This site has saved me some $$!

 

Wow. That's great news. Glad to hear the site has saved you $$ in your first 32 days as a Porsche owner. 

I was going to paypal a contribution, but if my posts are going to be spammed with pleas for money, maybe not. Plenty of other forums out there...

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SteelStroke Member

SteelStroke

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Posted

 

 

 

See my post on this issue.  It was a loose connector in the bracket...Took it out and plugged directly into the headlight assembly (There is enough slack in the wire to do so) and works like a charm.

 

Thanks! I'll give that a try. I just ordered a new connector from Pelican #999-650-150-40 ($9.75). Hoping the wiring to the connector is some sort of simple plug-in type arrangement that won't require a lot of soldering, but I'm probably wrong.

 

I have only been a 1st time Porsche owner for 32 days now.  This site is INVALUABLE!  Learn more and more everyday!  Consider a contribution.  This site has saved me some $$!

 

Wow. That's great news. Glad to hear the site has saved you $$ in your first 32 days as a Porsche owner. 

I was going to paypal a contribution, but if my posts are going to be spammed with pleas for money, maybe not. Plenty of other forums out there...

 

Not spamming...

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