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HID retrofit on 2007 GT500 - NEED HELP

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Hi everyone,


I am new to the forum (and all forums, never done them before). I am attempting an HID retrofit into my 2007 GT500 using OEM 2008 GT500 HID headlamp assemblies and a modified OEM wiring harness (courtesy of Marcello Canitano at SilverHorse Racing). The car is being put together right now, but I but noticed the difference in fuse junction boxes between the 2007 and 2008 models (based on wiring and relay diagrams from motorcraftservice.com). The 2008 HID version has fuses at F54 adn F55 for the HID relays, the 2007 version obviously does not. What's more, on my 2007, the location for F55 is completely blanked out, not even pinholes to put a fuse in.


I could either "modify" the fuse junction box and try and open two pinholes up at that location and hope that my contacts on the undersurface are good, or I can purchase a brand new fuse junction box. The part number off the fordparts website is 14A068A, but my Ford dealer says there are two versions and needs the last 8 digits of the part number, which can only be found on the fuse junction box itself.


So, if anybody out there has a 2008-2009 GT500 with HID headlamps, would you be so willing as to check what the rest of that part number is (14A068A-xxxxxxxx) and post online (or email me or send me a message, I'm not sure exactly how?) I'll be checking this forum topic site regularly. Any help is GREATLY APPRECIATED.


If I can get this to work, I will most certainly post back to the forum, as it appears many people have looked into this kind of OEM HID retrofit for their 2007 GT500s and GTs but few have been successful (or at least posted successfully).





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Thanks for the quick reply.


Can I ask:


- did you do the SilverHorse Racing mod on the harness? any other mods? the reason I ask is we can only get one headlight to work, and in the process found some other issues. So if you were able to get it to work on a GT500, it would be great if you could let me know, or alternatively if you had to do other mods so that we can try those to troubleshoot.


- if you didn't change the fusebox, then are fuses (F54 and F55) not necessary for the HID relays?



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I spent a long time with this, and it turns out that the 07 does not have the same fuse box as the 08-09, its actually a programmable junction box the the ECU can control. The ECU can be set by the dealer to say you have HID or NOT. What this does it changes the voltage in the box to the headlights for the HIDs (which actually draw less power overall than the standard lights, after they power up). I had the same problem with headlights and the same flux in power levels etc as the harness in the ford actual tries to test the circuit resistance to see if the bulb is good, or it powers down the circuit. I'm sure you ran into all of this like we did. I have a good friend that works at the dealer, and he said the junction box could not be swapped and even if you could the ECU still won't have the option for HD. I didn't want to go through changing everything to make it work.


As for my solution, I tried custom capacitors etc and could not get the lights to provide high beams. I wanted high and low beams, which uses a different signal to move the actuator on the HD lights. The fix was to build a custom harness that basically as two relays and a diode that when the highlights are switched to high, the power no longer flows to low side. The relays also require power for a short period of time to over come the voltage surge when starting. A fused link to the battery was created and only is in use at start up, after that it draws zero power and the harness provides the rest. Everything is hidden and compact, but I did cut the original harness where the plugs are to make the mod, but I have a spare factory harness, so I'm not worried about it. Everything needs to be water tight, and sealed.


So I'll stay tuned if you find another solution.. :lurk: But it's definitely worth the new look..




Test Harness - You can make it much smaller and cleaner.. The diode is between the purple and white (high/low wires, hard to see). Different colors on the side.


Edited by ccognetta

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Thanks ccognetta.


It took some effort, but we got it to work:


- did all the mods to the new 2008 wiring harness that were called for in the SilverHorse Racing website

- there was intermittent power to the HID relays off the main fuse box (bussed electrical center), plus there are no fuses for the HID relays in the 2007 BEC, so we decided to bypass the BEC altogether and power the HID relays (in the auxiliary relay box) directly off the (+) terminal at the side of the BEC. This also allowed us to fuse these connections.

- lights now work great: low beam, high beam, flash to pass, all work perfectly


However (there's always a however), one new issue just popped up today: now whenever I start the car, there is a warning on the dash info center that says "CHECK SECURITY SYSTEM". Does anybody know what that means, and why it would be popping up now? Could it be related to these mods, or something else? Is it potentially indicative of a systemic issue, i.e with us bypassing the BEC or smart junction box to power the HID relays? Or is it totally isolated?


Any help or thoughts from anybody out there would be much appreciated . . .



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