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Discussion Starter · #1 ·
2004 9-5 aero with xenon HID headlights

The drivers side HID headlight is not working, but I’m fairy confident it’s not the bulb or ballast. I swapped the left and right headlight assemblies and the problem did not follow the headlight unit

On the left side, everything works except the actual HID light coming on:
  • Flash to pass halogen lamp works fine
  • When I turn the high beams on, I can see the physical lens move like it’s supposed to
I tried checking the voltage on the connector and it looks like the voltages on each pin seem to be the same (although I need to check more carefully).

I was able to solve this problem a few months ago by cleaning the ground points under the battery, but this time the resistance from the headlight ground wire to the negative battery terminal is really low.

Has anyone encountered this before? What should I try first?
 

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Did you checked fuses with multimeter?
I have met several fuses that seems to be OK, but they are blown.
 

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Discussion Starter · #6 · (Edited)
Okay, I checked the fuses and they're fine. Zero resistance across them.

I also used the multimeter to check the voltage at each pin in on the headlight plugs and they're the same on left and right. I think this has something to do with how the car automatically lights up the turn signal bulb when the headlight isn't working, so [edit: no it doesn't, the turn signal light is always on] the voltages are might be different when a working headlight is plugged in.
Pin numberOFF LeftOFF RightON LeftON Right
10000
20000
30011.9811.98
40011.2811.27
59.69.69.329.32
60000
70000
8X (no pin)X (no pin)X (no pin)X (no pin)
90.460.460.470.47
1011.911.911.6811.66

Does anyone have any idea what I could do next to troubleshoot? I have been trying to look at the wiring diagram on WIS, but it's not easy to figure out what voltages I am supposed to see.

If anyone is a real saint and is willing to check these voltages on their own car, I would be eternally grateful.
 

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Could also be the orange, High Beam Relay under the hood fuse box. The solder joints are known for cracking and this occurring. Happen to me 6 months ago, on my 2005 Saab 9-5 Wagon/Estate. Fix is either a new relay or reflow the old one, which usually works well/cheaper. But RockAuto as confirmed working 3rd party relays for half the price from esaabparts or Eeuroparts.
 

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Saab do not switch front turn signal bulb instead of headlight bulb.
Those voltages are OK.
Xenon cars do not have orange relay, pin 5 sends failure info to MIU.

I still need to know if you really swapped whole headlamp assy from left to right and vice versa.
Do issue move or stay?
 

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Discussion Starter · #10 ·
Thanks everyone for your advice, my problem is [at least temporarily] solved!

While trying to diagnose the issue, I touched the fuse in the engine bay with my multimeter and the headlight lit up successfully. I cleaned the contacts for the left low beam headlight fuse and the connection seems fairly solid now. A bit of an anticlimax.

My theory hypothesis is that the bad connection added a bit of extra resistance to the circuit. This didn't affect the open-circuit voltages (when the headlight was unplugged), but it caused a voltage drop when the headlight tried to draw current, maybe below some cutoff below which the xenon bulb won't work at all.

Lingering question: is there a good way to clean these contact points (especially the socket), or might there be some loose connection inside the relax box that I should look at?

About the relay:
@thekrakenthatgames I don't have the orange relay. In the FR1 slot of the engine bay fuse/relay box [Front lights control/flash to pass] I have a bosch relay:
12V 20/30A
0 332 209 159
I tried swapping this relay with other relays of same type and I found no change, so I believe the relay is fine.

I am curious why I don't have the orange box, since it seems like I am supposed to.

Replying to @Mimmi :
Saab do not switch front turn signal bulb instead of headlight bulb. Yep, you're right.
Those voltages are OK. Thanks!
Xenon cars do not have orange relay, pin 5 sends failure info to MIU.

I still need to know if you really swapped whole headlamp assy from left to right and vice versa.
Do issue move or stay? I did try this and the issue stayed on the left side.

Thanks again to all of you for your help!
 

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I don't have the orange relay. In the FR1 slot of the engine bay fuse/relay box [Front lights control/flash to pass] I have a bosch relay:
12V 20/30A
0 332 209 159
I tried swapping this relay with other relays of same type and I found no change, so I believe the relay is fine. I am curious why I don't have the orange box, since it seems like I am supposed to.
As @Mimmi mentioned, Xenon-equipped cars do not come with the orange relay. The infamous orange relay applies to halogen-equipped cars only. My 2006 with Xenons has the same Bosch relay as you describe...no orange relay in sight.
 

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Discussion Starter · #13 ·
I do see fuses with corrosion on the legs, Usually simply replacing the fuse with a new one fixes the issue. I think corrosion on the sockets is less likely.
Okay thanks! I sanded the corrosion off the fuse legs and that seems to work pretty well. I might buy a few spare fuses and just replace the fuse if the problem comes back.

I should probably also go through and clean off the contact legs for the other fuses. Whatever cause corrosion on this one probably happened to the others.
 
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