DIY: C5 ACA Headlights + Modified Hi-4 mod + Healight Gear Replacement

[Pyro]

I spent some time last week on this headlight project and tried to document everything. I hope this helps someone or at the very least you'll enjoy the process. I figure I would combine these into one thread rather than have separate threads for each mod. There's some overlap in the steps and it's much easier if you're doing everything at once.

It should also be noted that I own a 1997 C5 and the earlier model C5's differ slightly from the later models so you may need different tools and sizes for screwdrivers/sockets etc


Headlight Replacement
Parts Needed
- ACA headlights (or any replacement headlights, the ones I got were the Radioflyer bi-xenon ACA headlights)
- OPTIONAL: XPEL Headlight protective clear film (part# H0603)

Tools Needed
- torx 15 and 20 screwdriver (i would recommend also having torx bits that you can fit into a small socket wrench)
- philips screwdriver
- socket wrench (10mm socket, socket extensions)
- 8mm box wrench
- OPTIONAL: PB Blaster (highly recommended)
- OPTIONAL: anti-seize

Before starting I would recommend applying the clear film before hand on another day. It will save you time and you'll get the enjoy the full beauty of your new headlights right away rather than have to wait for the little bubbles from applying the clear film to disappear. I didn't do this beforehand and in hindsight I wish i did. Also, I did one headlight at a time just in case i needed to use the other side as a reference for any reason but you could do both at the same time if you wish although i would not recommend it. Better to be safe. Speaking of safe, you might want to disconnect the battery or pull the fuses to stop the headlight motors from receiving power

1. Turn the knob on the headlight motor to manually get the headlight to come up and start by removing the headlight trim held together by 3 philips screws (2 on the inside and 1 on the outside). If you have trouble with one of the screws because the hood hinge gets in the way of your screwdriver, try a short screwdriver or alternatively close your hood and you should be able to unscrew it fairly easily

2. Remove the headlight cover, it's held down by 4 torx screws, 1 on each side and 2 at the back, be careful as you don't want to scratch the paint. Put them aside in a safe place.

3. Remove the 2 hinge joints with a torx bit/screwdriver and 8mm box wrench. These screws have loctite so go slow and be careful. I would recommend hitting these with some PB blaster. I found the screwdriver ineffective and went with the torx bit in a socket wrench approach. Also it was easier to use the box wrench to loosen the nut rather than using the socket wrench to loosen the torx screw. The screw also has a plastic piece to it so make sure you don't lose that!

4. Once the second hinge joint is out the headlight will fall into the headlight area so hold onto it and set it down gently. Place a towel over the brake vent where you can rest the headlight then loosen the 10mm nut holding the pivot arm to the headlight motor. If the pivot arm does not come off easily after the nut is off, gently pry it a little bit and it should slide off. Disconnect the hi and low beam connects from your headlights and label them so you don't get forget.

5. See below for HEADLIGHT GEAR FIX otherwise skip this step and go to next step.

6. Take the headlight somewhere you can work on it. With the headlight out of the way, now would also be a good time if you want to change the corner lights (which i did, it's pretty easy) that are just held down by a 10mm (inside, close to air intake) and 7mm (outside by the side marker light) nut on the underside and a spring on top.

Remove the 3 bolts (10mm) holding the headlight to the headlight bracket, you may need a socket extension for this part to make things easier, i think a box wrench could work as well

7. Now is a good time to hit the headlight adjusters with some PB Blaster as well and loosen them and make sure they work, you'll need them to aim your new headlights.

If you're working on the passenger side and plan on doing the HI-4 MOD (or my modified version) now is a good time while you wait for the PB Blaster to work its magic on your adjuster knobs. Test to make sure they work before putting everything back together.

8. Basically reverse the steps apply anti-seize to anything you see fit, tighten the 3 bolts to your new headlights, reattach the pivot arm, install the HIDs, they should be more or less plug and play if you have 55w HIDs, for standard 35w HIDs you'll need an inline resistor but it's not too difficult so for brevity I will skip over these steps, there are different ways to mount the ballasts. I'll let you decide what you think works best, but for reference, I simply used double sided tape to tape the ballast to wheel well. It's easiest to reattach the hinge joints last to allow yourself more room to install the HIDs but it's possible to do it after. Do the other side and then wait for it to get dark to aim your headlights

9. Find a level spot where you can aim your headlights at a wall. I'm no expert at aiming HIDs but i've read that the lower portion of the cut off shield should be 22"-24" high with the car parked 15-20 feet away

Here's the some shots of the headlights installed as well as some night shots of the high and low beams as viewed from various driving distances i tried to replicate in the rearview mirror from another car

Close and far highway distances, middle is low beam and right is high beam

City driving distance from rear view and side mirror. Top is low and bottom is high

Traffic stop distance. Top is low and bottom is high

 

[Pyro]

Headlight Gear Fix
Parts Needed
- Metal or plastic replacement gear (I went with a metal gear from Brent Franker which is one solid metal piece replacing both the plastic gear and rubber grommet)
- OPTIONAL: Bump stop replacement (OEM or I purchased from Rodney Dickman, this is optional but recommended)
- OPTIONAL: headlight motor washers (OEM or I purchased from Rodney Dickman, this is optional but recommended...there was a service bulletin TSB 00-08-42-002 for this)

Tools Needed
- 10mm socket wrench
- 1/4" socket wrench
- 10mm box wrench
- grease (not sure what works best but i used wheel bearing grease)
- epoxy (for later model C5s be sure to confirm which model motor you have in your car)
- pliers (maybe)
- OPTIONAL: anti-seize

1. If you're following along from the HEADLIGHT REPLACEMENT step 5 go to next step.

Turn the knob on the headlight motor to manually get the headlight to come up and start by removing the headlight trim held together by 3 philips screws (2 on the inside and 1 on the outside). If you have arms that fit behind the headlight you can get to the bolts, otherwise you'll have to open up the bottom plastic trim piece which means jacking your car up a bit. At the bottom of the front of the wheel well you will see 2 bolts, loosen those. Look under the car you will see another 3 bolts holding this piece in place, loosen those and remove the plastic piece. Now you can reach in from under the car. Side note, this is another way to change the corner lights and bulbs

2. Disconnect the connectors to the headlights if you haven't already. There's also a main power connector for the headlight motor which needs to be disconnected and detached. Apparently it just slides off the clip but i couldn't figure it out so i pushed the entire clip and connector out from the wheel well.

Here's a picture looking up towards the top of the wheel well, the brake duct is on the top left

3. There are 3 bolts that hold the motor in place. I think on later models they are on the outside but on mine the bolts were on the inside behind the headlight so not fun getting to with only the headlight trim removed. If you are doing this separate from the HEADLIGHT REPLACEMENT there is an additional nut that must be loosened to disconnect the pivot arm

4. With the motor removed from the car, remove the motor cover. On early model C5's you will need to remove 3 1/4" bolts, on later models you will need to pry the cover off

5. Replace your old gear with your new gear of choice. The gears i selected replace the rubber grommet as well. If you also go this route make sure the shaft sits flush with the gear and snug with no wiggle room when seated. If it doesn't fit turn the gear a quarter turn and try again, do this until you've made a full circle. If none of them fit just right you will have to take some pliers and very slightly bend one of the offending tabs in or out so that the shaft slides into place snug

side by side comparison of the new metal gear (left) and old plastic gear (right)

6. Apply generous amounts of grease on your new gear and also the worm gear in the casing

7. Put everything back inside the casing the way you found it and tighten the 3 bolts. For later C5's you'll have to epoxy this together and wait for the glue to cure before going further. I've read that these motors take quite a bit of stress so make sure you have some strong epoxy of else the cover will separate from the casing

8. If you purchased the bump stops go ahead and replace them otherwise skip this step. They are beige in colour, 4 per headlight, 2 on the back bracket and 2 by the motor where the pivot arm is. They slide right out and pop in some new ones. I've read with metal gears they tend to wind up tighter and sometimes may cause issues where the headlight may not pop up consistently. This is a symptom of worn bump stops. I had this issue and as you can see the bump stops that make contact with the pivot arm had a bite taken out of them over the years. An alternative cheaper way is to just flip your bump stops 180 degrees so the pivot arm is hitting the unworn side.

top row old bump stops, bottom row new replacements

9. Re-install your motor apply anti-seize to bolts if you wish. If working on the driver side and you purchased the washers, place the washers between the motor and the bracket it bolts onto. Put the clip back and reconnect all the connectors then do the other side. You won't need the washers for the passenger side.

 

[Pyro]

Modified Hi-4 Mod
This mod makes the low beams stay on when you switch to high beams. With the Radioflyer bi-xenon headlights this mod definitely holds more value otherwise the bi-xenon will not work. Essentially this mod sends the high beam signal to the low beams thereby keeping the lows powered. In bi-xenons this would send a current to the cutoff shield to retract. The issue with the standard Hi-4 mod is that with the headlights down, if you flash to pass this will trigger send the low beams which is actually the signal for the headlights to come up so during the day if you flash to pass your headlights will pop up and go back down. If you never use this function it's not a big deal but i wanted to make mine work as if it were stock.

Parts Needed for Hi-4
- Relay + wires + electrical connectors/eyelets OR Hi-4 Harness

Additional Parts Needed for modified version
- second relay
- wires
- electrical connectors

Tools needed
- 12mm socket wrench (I think...i don't remember the size for the battery node by the fuse box)
- 8mm socket or box wrench
- electrical tape
- OPTIONAL: wire loom
- OPTIONAL: small knife
- OPTIONAL: dieletric grease

Here's a rough electrical diagram of what i'm trying to accomplish the numbers correspond to the pins on the relay, they are labeled and you will be able to read them. In simple terms what this is saying is "Relay #1: If the side marker and high beam are ON, then send power to Relay #2. Relay #2: If Relay #1 is sending power, send power to low beams"

1. If you're doing the standard Hi-4 skip ahead to step 5

The modified version requires tapping into the side marker bulb as that is the most consistent indicator i could think of for the headlights to be up. It is possible to turn your side marker and parking light on without your headlights up but I think that occurrence is rare enough that we can use it (at least for me)....I mean how often do you guys turn the headlight stalk one click to get the parking lights without popping up the headlights?

Anyway to get at the side marker there are a few ways. If you followed from the HEADLIGHT REPLACEMENT above then you can access the bulb right away with the headlight out. Or you can remove the plastic trim piece in front of the wheel well under the car held by 5 bolts. Or you can push the brake duct aside and if your hands fit, you can maybe reach the bulb from there or get someone with smaller hands to do it for you. Side note, this is another way to change your turn signal bulb

Here's an example of the brake duct trick. My hand doesn't actually fit that far in but i did just to show you what it would look like

2. It's easier to run the wire from the battery down to the side marker rather than the other way around...depending on how lazy you are and how much you want to hide the wire. I also used a wire loom.

Start by running the wire (with wire loom optional) under the fuse box and through the battery divider.

run the wire along the side of the coolant reservoir where the existing harness runs as well. have your wire (and wire loom) follow this harness down behind fans and under the main beam. You can zip tie it all together.

3. Once you have your wire (and wire loom) all the way to the side marker, make sure you give yourself enough slack and tap into the +ve wire (general rule of thumb is the one that's not black). Electrical tape everything back up and then put the bulb back

4. You'll need some female spade connectors and wires (don't have to be too long I don't think i cut mine much longer than 6 inches and that was probably too much) to attach to your relays. So the long wire from the side marker goes to pin 86. pin 87 will tap into the high beam fuse (#9) in the underhood fusebox. 2 options here you can either just make your own wire or what i did was disconnect the high beam wire from the Hi-4 harness and reused it in my relay since this wire has a fuse tap on the end making for a cleaner looking install. pin 85 is ground tap the other end into the ground wire of the Hi-4 harness. pin 30 will go to the Hi-4 harness

5. The Hi-4 Harness is just a pre-made relay that's ready to install so you can make your own for much cheaper if you wanted to. My headlights came with the Hi-4 harness so i just reused it...connect the red wire (pin 87) to the battery via the nut on the fuse box (hidden directly below the wire loom in the picture of the fuse box below). The 2 wires from pin 30 go to the low beam fuse (#8 and #10). The black wire (pin 85) goes to ground. There is a grounding point if you move the battery divider out of the way a little at the bottom beside the battery

and lastly
Standard Hi-4: connect the high beam wire (pin 86) to the high beam fuse (#9 under hood)

modified Hi-4: take the wire from pin 30 of the first relay and connect it to pin 86 of the Hi-4 harness/relay

Here's a picture of the modified Hi-4 mod, I only had white wire and I wasn't about to buy new coloured wires just for this...but you can see white wire with wire loom on the right is the side marker wire, middle white wire goes to high beam fuse, and wire on left loops into the Hi-4 harness/relay

6. This step is optional but i noticed the fusebox lid was pinching the wires...not sure if there's a way to run this wires through the fusebox somehow but for now i made 2 small incisions into the side lip of my fuse box lid and folded it up so it gives the wires some room to stick out. Here's a picture before i folded the lip back so you have a rough idea of what i did. Not really rocket science here

Couple quick shots of the highbeams and keep in mind with the headlights DOWN this modified version will not make the headlights pop up when flashing to pass. The standard Hi-4 mod will so if that bugs you do the modified version!

phew sorry for the long post! If you got this far then thanks for reading! Hope you enjoyed it and I hope it helps someone. Happy modding everyone!

 

[Black 03 Z06]

Pyro, really good job on putting this technical/photographic information together. Very well done.

I have ACA headlights in mine, I was not aware the Xpel covering was an option. I wonder if it could still be applied even though the lights are installed.

Any one with a C5 really should consider this modification, the factory headlights are just terrible. A couple of Hurricane Lamps would work better

 

[Riley P]

Great write up Pyro! I love the ACA headlights and DEFINITELY would have went that route but when I was looking for headlights, it was rumored that the ACA lights were no longer available. Also, George (Radio Flyer) didn't get his hands on them yet to modify them and install bi-xenon projectors. So, I went the fixed route....

 

[nascar03]

Pyro...
Thanx for the headlight tech write-up.
Well done.
I'm going look into these mods.

Graham

 

[Pyro]

Thanks everyone!

@Black 03 Z06: You could definitely apply them now, just make sure the lens surface is clean

@Riley P: At some point when I was looking into them they were discontinued and only cheap knock-offs were available but it seems Radioflyer has been able to source new suppliers to have them made again! Fixed headlights were also something I considered but I was talked out of it by a friend.

@nascar03: These mods are definitely worth consideration if you're unhappy with the stock headlights and I figure I might as well change the gears while I'm at it instead of waiting for them to fail before doing anything. Hope my write-up serves you well if you decide to do them. If anything is no clear feel free to pm me any questions

 

[Riley P]

Very good to hear. Those headlights are one of the absolute best upgrades to the C5 out of any mod. They really help bring the car up to date and one of the big reasons why I upgraded my headlights was because I was tired of not being able to see on the highway.....and that was at 100 km/hr! So, being able to see and have a great looking upgrade is a win-win!