DIY: Tailgate Ajar Switch

Discussion in 'How-To/Tech Database' started by Kevan, Dec 1, 2008.

  1. Kevan

    Kevan SRT-10 Owner

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    "TAILGATE AJAR" MODIFICATION FOR *ALL* 2004-2007 DODGE RAM TRUCKS

    A few weeks ago, I put some window screens that needed repair in the bed. As I set them in there, I was distracted by the phone ringing. After my conversation (letting the pollster know that I had already cast my vote for Mains), I hopped in the truck and began running my errands.

    When I got to the place that does the screen repair, I was shocked to find that my tailgate was down!!!! I had forgotten to put it back up before I left the house.
    Luckily, the screens were still in there (which is amazing considering the way I drive. LOL).

    I got back home and was pissed at myself for not checking the tailgate. Since I normally park the truck 'nose first' in the garage, I don't usually look at the tailgate before I leave.
    With the tonneau on, I can't physically see if it's up or not. The mirrors are no help either.

    I came up with a plan!
    (insert sinister laughter here)
    We have "DOOR AJAR" switches in the doors....so why not one for the tailgate? Why OEM's don't do this, I will never know. It's cheap, easy, and would be a great selling point.
    Anyway, since they didn't do it, I will.

    I researched this subject a bunch, and found that other truck owners had tried to do the same thing: a mercury switch inside the tailgate.
    The problem was that whenever they'd hit any decent sized bump, the switch would 'activate' from being bounced around, and announce that the tailgate was ajar, but only for a split-second. They subsequently removed the switch and gave up on the project.

    I don't give up that easily. LOL

    I purchased a mercury switch from a car stereo supply place online for $5, and began the project.....


    TIME: approx. 2 hours + glue drying time.
    DIFFICULTY: 3
    COST: Less than $20.
    TOOLS
    - Wire strippers (good ones)
    - Wire cutters (good ones)
    - Soldering iron or crimping tool.
    - T-30 Torx bit
    - T-40 Torx bit
    - 3/8" drive socket wrench
    - 6" extension for 3/8" drive
    - Razor blade (new!)

    SUPPLIES
    - (1) Mercury switch (about $5)
    - (20') 16 AWG or 18 AWG copper braided wire.
    - (2) 150 ohm resistors (Radio Shack has them; 5 for $1)
    - (15-20) 1/8" zip ties (black preferably)
    - 1/4" heat shrink tubing (black preferably)
    - 1/2" heat shrink tubing (black preferably)
    - Clear strong-holding glue
    - Toothpicks
    - Masking tape
    - Electrical tape

    VEHICLE PREP:
    - Remove spare tire (gives you room to work under the rear of the truck)
    - Disconnect NEG. battery terminal (otherwise you'll be hearing your dash ding and your lights flash like SaturdayNightFever's dance floor as you hook up the switch and mount it.


    RUNNING THE WIRES
    The wires need to go from the tailgate to the driver's side door.
    Wait- "Why run 2 wires? Can't you just ground to the tailgate?". No. The tailgate is not grounded to the rest of the vehicle. Kooky, but true.

    Start by removing the access panel on the tailgate.
    There are (10) screws that need to come out using the T-30 Torx bit:
    [​IMG]
    (I cheated a little and used a drill...heh heh)

    On the driver's side of the tailgate, along the bottom, you'll find a small access slot.
    Using a piece of fairly stiff wire as a type of fish tape, run it in through the bottom:
    [​IMG]
    ...then up through the hole in the support beam on the inside of the tailgate:
    [​IMG]

    Take your two wires (preferably red & black) and tape them to the fish wire:
    [​IMG]
    ...and pull your red/black wires through.

    I made a little wire reel from a coat hanger:
    [​IMG]
    It worked out quite well.

    Wrap the ends of the red/black wires with electrical tape. This not only helps with the 'fishing' process, but also keeps them the same length.
    You can also give them a quick band of electrical tape every 18" or so. Makes for a really clean install (no wire slack).

    I then ran the wire up the length of the truck to get an idea of how much wire I'd need:
    [​IMG]
    I went from the tailgate up to the front of the bumper (about 15' on RC trucks; about 20' on QC trucks).

    The wires were run just behind the bumper cover, and right along the OEM wire loom lines toward the front of the truck:
    [​IMG]
    Notice that I added a healthy strip of heat shrink (about 8") to the section that will be exposed between the bumper cover and the slot of the tailgate.
    Weather and wear protection.

    Continue to follow the OEM wire loom, using zip ties to keep the new wires in position:
    [​IMG]

    [​IMG]
    Just do the temporary zip ties snug, so you can still adjust the length of the wires if necessary. We'll tighten them up later.

    It gets a little tight when it comes time to go past the gas tank:
    [​IMG]
    Tiny hands and a bucket full of patience will get your wires in the correct place. I ran the wires 'on top' of the OEM wire loom. Unless you remove the gas tank, there's no way to get to that section of the OEM wire loom.

    With the wires past the gas tank, we can now get them up into the cab of the truck (then into the door).
    Run the wires to the other side (outside) of the frame, and meet them up with the parking brake cable housing. This is your new wire guide.

    Open the door and remove the sill plate:
    [​IMG]
    (It just pops off via 2-way clips)

    Pull back the carpet slightly and you'll see the rubber grommet for the parking brake cable:
    [​IMG]
    This is our entry point into the cab.

    Using a razor blade (preferably an X-acto blade because it's just the right size), cut a SMALL slit in the rubber grommet, near the inside/back:
    [​IMG]

    Use some lube/spit on the new wires and feed them through the grommet:
    [​IMG]
    It will be a VERY tight fit. Be careful not to damage the wires or strip/damage the jacketing on them.

    Pull most of your slack through. Leave a few inches just in case.

    Now we can run the wires to the door.
    Just follow the parking brake cable:
    [​IMG]

    On the lower kick panel, you'll see some insulation held in place by (2) push rivets:
    [​IMG]

    These need to be popped out so you can get the wires hidden nicely:
    [​IMG]

    Next is the door 'joint'. This was really hard to figure out. There are markings on the rubber protector that say "PUSH", but when you push them, nothing happens. Frustration found out that the rubber grommet ends of the 'joint' can just be pulled out of the body panel (CAREFULLY!):

    THEN you can 'PUSH' on the top and bottom tabs of the big connector guide to release it from the body panel.

    Here's the grommet end on the door side:
    [​IMG]


    Migrate your wire running from the parking cable housing to the wire cluster that goes to the door:
    [​IMG]

    With the big connector slid out towards the door, you can squeeze your wires into the available space:
    [​IMG]
    I went with red on one side, and black on the other. That's really the only space available.

    Now is a good time to get out any slack you might have between the parking brake grommet and the door connector joint.

    If you compress the 'joint', you can slide wires through it:
    [​IMG]

    Re-seat the connection joint into the body panel:

    You will hear the tabs click once it's back into place.
    Replace the 'joint' cover on that side:
    [​IMG]
    TIP: Use some WD-40 on the rubber to help seat it.

    Now we need to remove the door panel.

    There are (4) Phillips-head screws: (2) on the bottom edge of the panel:
    [​IMG]

    [​IMG]

    .... (1) inside the side mirror cover section
    [​IMG]

    .....and (1) behind the door handle.
    [​IMG]
    We'll do the one behind the door handle AFTER we remove the handle itself.

    To remove the door handle, lift up on it (as if you're opening the door) and look inside. You'll see a bolt in there:
    [​IMG]

    Use a T-40 Torx bit and your extension to remove that bolt:
    [​IMG]
    It's in there pretty tight.

    Keep pressure on the bolt and use the handle to 'pull' it out of the door panel:
    [​IMG]
    Otherwise you could end up with a bolt rolling around inside your door. Not a pleasant sound.

    Now we can take the last Phillips-head screw off the door panel.

    Press the door lock button down, and with one hand 'lift' the door panel off of the door frame using the grab bar on the panel:
    [​IMG]
    Don't lift too far! There are wires back there that we need to disconnect!

    The window & lock controls need to be disconnected:
    [​IMG]
    Now the panel can be fully removed and set aside.

    OPTIONAL:
    While the panel is still attached to the door, you can pop the window & lock control panel out of it's mount:
    [​IMG]
    Take care not to break any of the mounting tabs on the panel.

    Lift it up on the panel and disconnect the window and lock controls:
    [​IMG]

    [​IMG]
    This also makes re-assembly a little easier as you don't have the control wires acting as a short leash while you try and get the mounting notches correct on the door frame.

    Okay, the panel is off and you'll see this:
    [​IMG]

    The protective plastic needs to be pulled back so we can access the wires behind it.
    They use this crazy tar-like goop to hold the plastic onto the door frame. The good news is that it's reusable and retains it's sticky-ness.
    I used a plastic scraper to 'cut' the tar:
    [​IMG]
    I only did 1/3 of the back and 1/3 of the front of the plastic cover on the door. This kept it aligned and from falling all over the place and getting that tar where I didn't want it.

    Our new wires can now be run into the door (back by the grommet), and then down to meet up with the main wire cluster:
    [​IMG]

    I re-attached the window controls and tested to make sure the new wires didn't get touched by the power window travel:
    [​IMG]
    They stayed well clear of the glass and the track.

    Continue to run the wires along the OEM wire cluster. I used elec. tape here instead of zip ties.
    Towards the rear of the door, look for this section of wire cluster:
    [​IMG]
    That's the one we want.

    With your razor, CAREFULLY slice through the section of cloth banding of the wires and spread them out a little so they can be individually accessed:
    [​IMG]
    (That shot actually shows the new wires soldered while I was testing, but I'm using it to describe the above information. Apologies for any confusion.)

    The wires we want to tap into are:
    [​IMG]
    - RED = OEM SOLID PURPLE
    - BLACK = OEM BLACK/PURPLE STRIPE
    Remember to get the heat shrink on there first, THEN solder the wires together.

    Re-band the entire area with new electrical tape:
    [​IMG]
    NOTE: I noticed that the door activation rod was putting a little wear on the jacketing of some of the wires. Not enough to warrant replacement, but it was definitely there.
    I used a couple of loops of electrical tape along the length of the rod to provide a little protection.

    BTW- If you're reading this on any site other than SRTConnection.com, it means that some asshat stole it from their site. Not only is that uncool, but it's also highly illegal.

    Okay, we're done inside the door.
    Remove any slack in the wires and make sure they're taped nicely to the OEM wire cluster.
    Re-"tar" the plastic cover onto the door frame.
    Attach the window & lock controls to the control panel on the door panel.
    Align the notches and the door lock button and slide the door panel down into place on the frame. It's a little tricky the first time you do it, but the panel will feel solid on the door when you get it right.

    Re-attach the Phillips screw behind the door handle area:
    [​IMG]

    ...the one up by the mirror cover plate:
    [​IMG]

    ...and finally the two on the bottom of the door panel:
    [​IMG]

    [​IMG]

    Using just the T-40 Torx socket and the extension, re-attach the door handle:
    [​IMG]
    (I know I cheated a little using the thumbwheel....sorry)
    Use the handle as a 'guide' for the bolt and to keep it from falling down into the door panel.

    There's no torque spec for that bolt, but make sure it's on there nice and tight. Not too tight- that handle is just ABS plastic so it *can* break.

    Check the door controls and that all door & computer functions are working correctly.

    We can remove any slack in the cab area, all the way down to the parking brake grommet.
    Re-attach the two push rivets for the kick panel insulation, and re-attach the door sill plate:
    [​IMG]

    We're done inside!
    Don't forget to close the door. :)

    Let's move under the truck again.....
    Starting at the underside of the parking brake grommet, remove any slack from the wires and work your way toward the tailgate.
    (The parking brake grommet should hold the wires tight enough for slack removal)

    Just before the front of the gas tank, I used a zip tie to keep the new wires with the OEM cluster.

    On the rear of the gas tank, I began stashing wires.
    Here I use the OEM wire loom and stuff as much of the new wire in there as possible.
    I used small sections of the 1/2" heat shrink on the portions of the new wire that went "around" the OEM wire clips:
    [​IMG]

    Shrink the heat shrink as you work toward the rear of the truck.

    Here's the elbow along the frame:
    [​IMG]

    ...and then along the lower edge of the frame:
    [​IMG]

    ....and finally up towards the bottom of the tailgate:
    [​IMG]

    Once the wire under the truck is secured, I can heat shrink that long 8" section and pull it toward the interior of the tailgate.
    The heat shrink should cover the wire that's directly exposed.

    Bring the wires up through the tailgate and out through our starting point.
    Trim the wires, strip about 1/2" off each end and tin them:
    [​IMG]
    Use some masking tape to hold the wires in place so they don't slip into the tailgate.
    Now we're ready to add the switch!

    BUT FIRST......


    BUILDING THE SIGNAL GATE
    Since mercury is a liquid, it will slosh around inside the switch as your vehicle moves about. Sharp jolts (like crappy pavement) can slosh the mercury around enough to cause the connection to make (or break).
    In our case, sloshing mercury would be a "false connection".

    In order to counter that, we need to install a signal gate.
    This little thing acts as a kind of bouncer for the signals that are allowed to be sent to the front of the truck (computer): If there's enough signal for a long enough period of time, it's allowed to pass.
    If there's not enough signal, it gets denied.

    My electronics buddies weren't much help when it came to this (most said, "Mercury switch? What is this...1973?" or, "12V system? Let me know when you graduate to AC" LOL)
    Mercury switches are pretty well built these days, and even non-mercury switches would encounter this same problem with bumpy roads.
    So, I was pretty much on my own for testing.

    The first signal gate came from an idea I got via a battlebot forum. It was the Tic-Tac cap+resistor setup that many of you saw.
    It didn't work.
    At all.

    So, back to the drawing board.
    I started with a 10Ω resistor and worked my way up.
    My neighbors must have though I was crazy driving back and forth between the garage/shop and the one nasty bump for hours that night. LOL
    But I finally got it:
    150Ω + 150Ω = WINNER!
    (NOTE: I tried a 330Ω resistor and it was too much. 300Ω is the max)
    You can pick up the resistors at any Radio Shack for about $1 (pack of 5).

    I soldered the resistors together then inserted them into a protective plastic case (Pentel eraser tube) with leads coming out of each end:
    [​IMG]

    Close-up:
    [​IMG]

    This isn't required, but it's a good idea to keep the tiny resistors protected in some way.
    My signal gate has quick connectors on it's leads because of all the testing.
    Yours can be soldered directly.

    Resistors work both ways, so you can hook it up however you like...to the BLACK wire.

    Now solder the leads from the mercury switch to your new wires. Don't forget the heat shrink!
    NOTE: I used quick connectors due to my testing. Yours should be soldered.

    Awesome!
    Switch is wired up and ready to be mounted!


    MOUNTING THE SWITCH
    The switch can be just stuck to the inside wall of the tailgate.
    BUT....if you do that, it will only 'switch' when the tailgate is 98% of the way down.

    I wanted it to 'switch' at about the 45º mark, so I came up with an angled foam mount for it.

    Using (3) strips of 1/2" weather stripping foam, I cut 3" pieces.
    Those pieces were stuck (glued) together, and I let them dry.
    This is the glue I used:
    [​IMG]
    It's got a great hold and is self-levelling (looks more pro). It also remains slightly flexible when dry. It can be removed simply by lifting up on it.

    With an electric carving knife (THE BEST tool for cutting foam), I cut from one corner to the opposite corner, essentially making (2) angled pieces.
    Here's what it looked like:
    [​IMG]
    You can also see the toothpick and remaining glue from the process.

    I took the foam, toothpick, glue and scrap plywood up to the truck.
    Since the double-stick tape on the mercury switches won't grip the foam very well, I applied a good gob of glue to the face of the foam:
    [​IMG]

    Leave it as a big gob/bead, and let the switch spread it out when you set it in place:
    [​IMG]
    Use some masking tape to hold the switch in place.
    IMPORTANT: Make sure the switch is oriented correctly!!!!!
    You want the leads of the switch on the lowest portion of the foam, and towards the TOP edge of the tailgate.

    I applied more glue around the edges of the switch and on the top edges:
    [​IMG]
    Kinda Alien-like, no? :)

    Let that glue dry for a few hours.

    Now you can add another gob/bead of glue to the bottom of the foam:
    [​IMG]

    ..and mount your switch into place inside the tailgate:
    [​IMG]

    Use some masking tape to hold it in position while the glue dries:
    [​IMG]

    I also added a couple of drops of glue to the wire leads to keep them away from the tailgate actuator rod:
    [​IMG]
    It acts as a type of strain relief as well.

    When the glue is dry, you can remove your masking tape.

    It should look a lot like this:
    [​IMG]
    Stray glue can be cleaned up with a plastic scraper.

    We're done with the switch and wiring, so let's button the truck back up....

    Re-install the tailgate access panel, and hand-thread the mounting screws:
    [​IMG]

    Then tighten them all up:
    [​IMG]

    The service manual states they should be "tightened securely", so I went through and did them all by hand until they were "secure":
    [​IMG]

    Raise the tailgate into it's normal upright/locked position.
    Put the spare tire back in it's holding spot under the bed.
    Re-connect the NEG. battery terminal.

    You're done!
    Test out your new Tailgate Ajar system!

    You'll notice that your in-cab lights come on, the dash dings, and the DOOR AJAR light on the dash illuminates when you lower your tailgate.
    Press slick, eh?

    If you regularly haul stuff and need the tailgate down for a long period of time, you can install a 'kill switch" for the tailgate ajar switch up on the dash above the parking brake lever. Cheap and easy.

    BONUS FEATURE!!!!
    For those with a factory alarm: If you used the remote to lock the truck and then open the tailgate, the alarm will go off!!!
    Yes- I accidentally found out about that......at 2:30AM....with the garage door open. LOL

    Enjoy your new feature!


    ©2008 Kevan J. Geier
    ALL RIGHTS RESERVED
     
    Last edited: Dec 3, 2008
  2. Quick

    Quick Mgmt. - I can't help you

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    :clap::clap: Most excellent! :clap::clap:

    I'm a little worried about wire wear at the gate/bumper. maybe some sort of gromet? Might even be worth drilling a hole in order to use a store bought grommet.

    I was a bit disappointed in the foam mount for the mercury switch... I was fully expecting "...the foam should work fine for you (peasants). I used it as a template to fabricate this metal mount..."

    Good job!
     
  3. Kevan

    Kevan SRT-10 Owner

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    I was a little concerned as well, but....the tailgate is not being opened/closed as often as a door, so I think the heat shrink should provide plenty of protection against not only the elements but also regular usage (lowering/raising of the tailgate).

    You know me too well. :D
    Here's a shock mount that I fabricated:
    [​IMG]

    [​IMG]

    :D
    Note the larger flange nut being used as a counter-weight.
    It worked sometimes, but not well enough to meet my criteria.
    I hope the plexi doesn't mean I let you down. LOL
     
  4. Quick

    Quick Mgmt. - I can't help you

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    hmmm, as long as it doesn't crack over time from the vibration :grin:. Something with a full triangle might be in order.
     
  5. 1bad4dr

    1bad4dr Mr. Meany

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    Damn Kevan.

    Hats off to you buddy. Yet another GREAT DIY. :worthy:
     
  6. bee0912

    bee0912 Rumble Bee 0912

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    Nice job Kevan! Do you know what the best part of this one was??? You did not once ask me for my expertise!!!!!!!!!! JKJK you know i am here to lend a hand when ever.
     
  7. StevoSRT

    StevoSRT Moderator

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    damn....just damn hahahahaha

    I want you to invent a super crazy tonneau cover that doesnt suck for carrying stuff in your bed.....cause I hate caps and i wont have a truck without a cover hahaha
     
  8. Kevan

    Kevan SRT-10 Owner

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    Thanks everyone!
    Glad you like it.

    I have a 1:8 scale prototype of one in the shop.....
     
  9. StevoSRT

    StevoSRT Moderator

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    lol normally i'd think this was sarcasm....but you do dont you hahaha

    I have never seen a good cover that could serve all purposes....at least not one that i liked
     
  10. bee0912

    bee0912 Rumble Bee 0912

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    This is the one kevan has and it is by far the best on the market!

    http://www.ltsportcover.com/tonneau-covers/dodge-ram-xf.htm

    Light weight

    comes off in all of 1 minuet with two people( if it wasn’t for it's size one person could do it)

    SRT wing mounts on it perfect

    flush with the bed rails so it does not look like crap

    Aluminum!!!!!!! it holds a few hundred pounds no problem
     
  11. Kevan

    Kevan SRT-10 Owner

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    Yes.
    Yes I do.
    Keith's been in the shop dozens of times but hasn't seen it yet. It's pretty stealthy. :)
    I might sell the design to a company somewhere down the road. We'll see.

    The Lazerlite that I have on my truck now is great.
    No-drill install, only sticks up about 1/8" off the top edge of the bed rail, EASY on/off, and is strong as hell (1500 lb. limit on the top!).
    And, the one thing you can't put a price on: customer service. It's AWESOME!
    The trim around the outside edge of mine had started to come un-adhesive-foamed. A quick email to the company, and 2 days later brand new (lower profile with much better glue!) trim showed up. No charge. WIN

    There is one small downside, however:
    The tonneau needs to be lifted slightly to close the tailgate.
    That's kind of a good thing though, as it means a better/tighter seal for the bed.
    The issue can be solved by replacing their weather seal with a 'flap-type' (like a squeegee blade) seal along the back edge of the tonneau. Cheap and easy to do.


    To keep it on topic, the tonneau does not interfere with nor affect the tailgate ajar modification. :D
     
  12. Kevan

    Kevan SRT-10 Owner

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    Final install pics added (with signal gate).

    Enjoy!