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  1. #1

    Default wiring a Remote Controller for 76 Merc Thunderbolt 500

    Here is my problem. I have a 76 Mercury Thunderbolt 500, that was missing a remote controller. The engine harness was bad so it was replaced with a CDI aftermarket harness. Mercury no longer makes a harness for this motor. Not a big issue since the CDI harness is properly wired and conforms to the OEM harness. After extensive research I have found a Remote controller that I believe can be wired to work. Unfortunately I am trying to mate 2016 remote controller to a 1976 Engine. The remote controller I am working with is a 2016 Mercury Mariner 881170A7. This controller doesn't incorporate electric trim or engine overheat horn, which matches the engine. However, a few things have changed, such as engine cutoff lanyard.

    Either way I have searched everywhere for a wiring diagram for this controller with no luck. A talk to Mercury always ends up worthless since they don't like to talk to end users and always seem to want to point you to a dealer, who doesn't want to be involved in projects. I finally received a diagram from Mercury for the controller, which I could work with if I understood the references. Color of wiring, Perfect! connections of T1-T7, reference, purpose????

    Anyone out there been through this before, any insights, experiences, helpful ideas??

    Looking for guidance

    Thanks

    Larry

  2. #2
    Join Date
    Sep 2008
    Location
    Maryland - USA
    Posts
    8,065

    Default Re: wiring a Remote Controller for 76 Merc Thunderbolt 500

    Its not going to be an easy task - the newer style stuff has connectors everywhere where the bicentennial stuff didn't.

    I'd be inclined to disassemble the new control box, remove the harness whip, and hardwire the new wiring into the controls on the box....seal up all the new connections and reassemble....

  3. #3
    Join Date
    Sep 2010
    Posts
    18,422

    Default Re: wiring a Remote Controller for 76 Merc Thunderbolt 500

    The cutoff on a 2016 might CLOSE the circuit to stop the engine.-----The 1976 motor might need to OPEN the circuit to stop the motor.-----Nothing like supporting your local dealer so they will help you.-----And most dealers today are not interested in helping those who spend the money online and then come looking for " advice on a budget " so to speak..-------Best to get the correct control box , should not be hard.

  4. #4

    Default Re: wiring a Remote Controller for 76 Merc Thunderbolt 500

    I believe it is a doable task,and I think I might have found a solution. First I had to find a replacement harness, Mercury no longer makes one. For that I turned to CDI electronics, (www.cdielectronics.com). The motor originally had a 7 wire harness to the old MercController. Replacement for my motor was a CDI 474-9550 Harness.
    From there I had to find a controller with no electric trim and no overheat horn. I purchased a new Mercury 881170A7 controller. Surprisingly it had a 7 pin molded connector.

    This is where I was at when I posted my original post. I was hoping to find out if anyone had knowledge on wiring these two. I wish I had read your response earlier. Your rewiring solution is a good alternative that I had not considered.

    My solution was stalled because I was hesitant to pull the trigger on cutting of the factory plug off the new controller and thereby making it mine. Once I accepted that requirement I was able to quickly identify all wires and colors, mate them to the new engine harness, and Tach plug with a simple continuity check.

    After I put it back on the motor and have a chance to test it I will post my solution and schematics in case someone else finds themselves in a similar situation

    Thanks for your input though.,

  5. #5

    Default Re: wiring a Remote Controller for 76 Merc Thunderbolt 500

    Quote Originally Posted by racerone View Post
    The cutoff on a 2016 might CLOSE the circuit to stop the engine.-----The 1976 motor might need to OPEN the circuit to stop the motor.-----Nothing like supporting your local dealer so they will help you.-----And most dealers today are not interested in helping those who spend the money online and then come looking for " advice on a budget " so to speak..-------Best to get the correct control box , should not be hard.
    Most outboards including the 1976 Mercury Thunderbolt 500, close the circuit to ground to shut the motor down. When you turn it off or pull the cutoff switch, all that is being accomplished is closing the ignition circuit to ground. The run function is based on an open circuit. My engine harness 7 wires with minimal functions since my motor doesn't employ electric trim or engine overheat horn.

    Thank you for responding back, and I totally agree with supporting a local dealer. However, my problem was that many local dealers are filled with mechanics who weren't even alive in 1976. Many have lost or never developed a mechanical problem solving mind. They come from the plug and play era and totally shut down if it involves more then simply changing a part.

  6. #6
    Join Date
    Jun 2013
    Location
    Duluth Mn
    Posts
    2,428

    Default Re: wiring a Remote Controller for 76 Merc Thunderbolt 500

    I have a brand new control for a 1976 402 here in it's Merc box. Let me know if you succeed or not.

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