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Discussion Starter · #1 ·
Here's a modification of my own design that I just finished, and I think you guys will like it.
I borrowed the idea from Chevy's police option T53: Alternating trunk lid warning lights. In the Caprice police car, two Peterson red 4-inch trailering lights are mounted to the inner trunk lid and wired to a small alternating flasher which is fed power via a mercury switch only when the trunk lid is raised. I decided to install a similar option on my '96 S-10 Blazer such that two red lights flash in an alternating pattern whenever the glass hatch is raised. Here's how:

1. Obtain two Peterson single faced 4" diam. red ligts from K-Mart or Wal-Mart. Cost approx. $6-7 each. There are two different kinds, the one I used has a black metal housing, the one with the plastic housing works equally well--but make sure they're single faced.

2. Obtain a 12 volt, 3 terminal heavy duty flasher, Wagner #537. Pep-Boys insists that this part doesn't exist, so you'll have to go to a local parts store to get it, or to one of the better chain stores. Costs $3-5. It looks like an aluminum-colored hazard flasher, except it has 3 prongs instead of two.

3. Yank a mercury switch from a car in the junkyard.


4. Open the tail gate glass. Stick your head in the cargo area just slightly and look up, you'll see a small interior light centered in the plastic bezel between the upper liftglass hinges (I didn't know this light was here until I found it accidently). Pull down the entire center bezel section (maybe a foot and a half in length). The wire for the interior light wil become the hot wire for your flashers.

5. With the center bezel off, the side bezels will be the only ones left attached--they curve up from the sides and ride up to the top--they actually continue to ride under the center bezel. Pick a flat area up top along the roof--not a rounded corner area, and not an area wher the center bezel will overlap--this might require some experimental measuring. Carefully drill a hole (not too big) into this upper part of the side bezel. Do the same on the other side--the hole should be just big enough for the threaded post of the peterson light to fit through. Then bolt your light in so that it hangs down. Ground each light by running a wire from the stud of the light assembly to the metal roof (drill a hole into the roof--it's hollow and won't go through the outer roof panel--bolt your ground wires in). The two lights should look as though they're mounted up top as far away from the center as possible, but not quite into the curved corner areas.

6. Open up the left rocker panel where the jack and wrench are stowed. Wiretie a worm gear hose clamp to the bundle of wires that runs through there. Then slip your wagner flasher into the hose clamp and tighten slightly. Also, IN the rocker panel itself, drill a hole down low on the rounded plastic edge and install a toggle switch from Pep-Boys--this will be your cut-off so the lights don't flash in your face at night when you're unloading groceries. Make sure there's enough clearance so the switch isn't hit when the tailgate is slammed.

7. Splice a wire into the interior light hot wire. Connect this new wire to an in-line fuse, and from the fuse to the toggle switch you just installed. Then run a wire from the toggle to the mercury switch. Hold the switch in different positions, and with a meter, or with one of the red lights, verify which position turns the swictch on. Once you've determined the correct position, wiretie the mercury switch to the rear glass defroster plastic electrical connecter (you know... the connecter that snaps onto the metal prong soldered into the glass. When the liftglass is up, the mercury switch should be ON.

8. Run a wire from the other terminal of the mercury switch (which should be hot when the toggle is on and the glass is up) back down to the alternating flasher, and connect it to terminal "X" on the flasher.

9. Wire terminal "P" of the flasher to the BRAKE lamp wire (white, I think!) of one of your red lights. Don't use the brown wire which is for the dim running light (please verify these colored wires for yourself using a power supply).

10. Connect terminal "L" of the flasher to the other red light's brake bulb wire. The flasher itself must not be grounded directly, because each light is grounded to the roof, ref. Step 5.

11. Tuck all wires behind the side and top plastic bezels. The ONLY two wires that should be visible when the job is done are the two wires running up and down from the mercury switch.

Your lights should now flash in an alternating pattern when the liftglass is raised and should shut off when either the toggle is thrown, or when the glass is shut.

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