fsm

Hi - I purchased HID kit for my low beams (55w H1, 4500k) + for the fog light (35W H3) from DDM Tuning for my '97 C4S. I also use the fog as DLR lights (Canada regs). Install was pretty straightforward (thanks to great posts from JPP https://rennlist.com/forums/993-foru...-fog-test.html and TRM https://rennlist.com/forums/993-foru...stall-diy.html).

Both worked well but the fog light stopped working after a few days. DDM Tuning support suggested to do a direct battery test to determine if the problem is with the HID kit or with the interface of the HID kit with the stock wiring/electrical system of the car. The direct battery test worked. DDM assessement is :
"If the HID kit works fine during the direct battery test, then the problem with the HID has to do with its compatibility with the vehicle. Depending on the particulars, the solution may be to purchase a wiring harness, to check for loose connections, to purchase error code eliminators. If these solutions don't seem appropriate, we'll be glad to advise."

Essentially so anybody experienced the same issue and bought a wiring harness (plugged in directly on the battery) or an error code eliminator?

any insights appreciated. thanks in advance

Francis
'97 C4S

TRM

Francis, All I can say is from experience I know the 993 wiring is rather quirky. If any change occurs in resistance to certain circuits things can stop working. Found this out when I removed the little ashtray bulb, only to find it royally screwed up my dash lights. Replaced the bulb and problem solved.

The direct to battery harness might be a good choice in this case. I believe the ballasts for the HID kit need to gather up some amount of charge in order for the bulb to fire and stay lit, like a capacitor. Going direct to 12v might be a good fix.

ilko

I've had my 35W HID fogs on the car for over 2 years (7K miles) without issues. For the last year I've been using them as DRL. I purchased mine from www.vvme.com.

3healey

I installed HID low beams using the factory wiring. After about a year, one side quit working. After some basic trouble-shooting, I determined that the ballast had failed. When I contacted the supplier, they told me this is a common problem with Porsches and recommended I use a harness w/relay and get 12v direct from the battery. They also graciously replaced the bad ballast. No problems since.
Knowing what I know now, I would definitely wire in a relay and use 12v direct from the battery.
Let us know what you decide to do and how it turns out. I am not impressed with the foglights on my car and might consider an HID replacement.