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Discussion Starter #1
Collected a new to me 2008 C70 T5 last week and have been chasing an issue with one of the fog lights. The drivers side fog light, closest to the fuse box, works great. The passenger side fog light, further from the fuse box, does not work.

Actions Taken So Far:
  • Swapped the bulbs, both bulbs work in the working side
  • Disassembled the connector, no corrosion etc
  • Ground wire continuity is good
  • Run test wire from the battery to a bulb, bulb through fog light ground wire works
  • Vida test of fog light relay shows pass

Looking at page 85 of the wiring diagram, Group 35 Lighting Fog Lights C70

10/5 drivers side fog light, works
10/6 passenger side fog light, does not work
F29 15 amp fuse, good
2/34 Fog Light Relay - good per VIDA
31/110 - grounding location pass side strut tower - for 10/6 - good

So - it seems there is a disturbance somewhere along the green wire with white stripe between the fuse box and the fog light. I am uncertain regarding how to determine where the problem is. I have removed the bumper and removed some of the wiring loom material close to the fog light to see if there was a clear break in the wire.

Questions
1. How can I test the wire from the fuse box? It seems based on the wiring diagram the power for both fog lights comes out of the relay. How are the relays removed? there is no clear way to grab it and remove it like the fuses.
2. Is there a common place in the harness where the passenger fog light wire breaks?

Thanks in advance for any guidance
 

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Discussion Starter #2
Removed the battery and battery plastic box today for better access to the wiring harness and discovered the unfortunate reality that the wiring harness near the firewall has been chewed on by a rodent or similar creature. A decent section of foam insulation was also chewed apart, likely by the same offender.

There was actually an approximately 2" section loose green wire with white stripe (Fog light wire) resting on the metal "Shelf" under the ABS pump and master cylinder area. I suppose I am lucky that something more critical was not damaged, however if something more meaningful was not operating I would have avoided purchasing the car. Fog light issues always seems like a simple bulb.

Now to figure out how to access this wiring harness section for repair.
 

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Discussion Starter #3
After removing the "foot" / mount for the ABS module and unplugging the ABS module I completed a challenging and frustrating wiring repair with absolutely minimal access. All back together with crimp connectors, heat shrink, and automotive fabric-type electrical tape.
 

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Yes, rodents seem to like the C70 wiring harnesses. Here's what I found under the plastic engine cover the last time I replaced my spark plugs - thankfully no issues other than mouse poop:
 

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Discussion Starter #5
Wow - must be something tasty in the plastic sheathing that rodents can't ignore.

If the rodents do enough damage to yours I'd be happy to take that cranberry interior off your hands LOL.
 
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