Mine is – er, was. It began as an intermittent – now there’s a word that no wrench likes to hear – problem. Then, one day, Pam almost got stranded.

I’ve got a pretty good relationship with the dealership. They handle most of the maintenance work on this truck mostly because I don’t have a shop manual. (They’re important, y’know, and I have one – or a set – for all of the other vehicles, but that’s a story for another day.) The dealership treats me pretty good. They allow me into the service area to chat directly with the techs and even cut me nice price breaks often enough to matter.

There’s a procedure in the user manual for overriding the interlock on the shifter. (I wouldn’t have thought so, but Pam suggested looking there. For once I listened. Smart girl.) So override I did and went to let the pros have a look. Two birds, one stone, it was time for the 75K service interval anyway.

A couple of hours later they told me the shifter assembly needed to be replaced. Actually, it was just one part of the assembly, but I had to buy the whole thing: $370 for the assembly, $130 for the labor to install it, plus tax and what have you. They’d have to order it so in the meantime the tech managed to get this one working. My options were to order the part and schedule the swap, or leave it be and see how long the fix would last. When it failed (when, not if, I noticed the choice of words) I could call the order in and they’d take if from there.

I chose to let it go for now and take my chances. That was the end of June and now it’s the beginning of August. I was in Asbury Park one night last weekend when it failed. I applied the override and got on my way.

Today I implemented my own fix, which I suspect will last longer than theirs. Before I continue I need to tell you that I’m not recommending that you perform this hack on your own vehicle. It disables a part of the safety interlock that prevents you from accidentally shifting out of Park. I personally don’t have a problem with that because I’m an Old Guy that grew up without those damned interlocks, back when you could freely shift the transmission however you pleased at any time.

Let me describe the interlock system. There’s a button on the shift handle which, through a series of internal levers, must physically move a lock that trips whenever the lever is placed in Park. That kind of interlock has been around forever. Some column shifters, for example, required you lift the handle toward you before they’d move out of Park. Implementations vary but they all accomplish the same thing. But there’s an additional interlock here, one that prevents the button from moving unless the ignition is on and your foot is on the brake. Naturally, this is an electrical interlock. There’s a solenoid in the shifter assembly that, when electrically actuated, moves a smaller physical interlock within the button, allowing it to move. This second interlock is tied into the ignition circuit and the brake lamp circuit. Yes, what you’re thinking is true; if your brake lights fail in certain ways or if the fuse for that circuit blows, you’re stuck in Park. When the system is working properly you listen can carefully and hear the solenoid actuating as you press and release the brake. The override mechanism mentioned earlier is a tiny lever that, when pressed, simply does what the solenoid does – allows the button on the shifter to move. In fact, when the system is working properly you can see the override lever move when the solenoid actuates. Whenever the lever is not in Park, the lever remains in the override position.

In my case, I knew from testing that the ignition, brake, and brake lamp circuits were operating properly. The intermittent was that sometimes the solenoid would actuate and sometimes it wouldn’t. Solenoids are simple electromechanical devices. I’m guessing that there could be an intermittent open circuit, maybe caused by something as simple as a solder joint gone cold from vibration or age. Or the mechanical part of it is sticky or binding, where the correct electrical signal is present but it can’t physically move, sometimes. Either way, the shifter assembly needs to be removed for disassembly and troubleshooting. There’s where that shop manual, the one I don’t have, would be handy.

My fix is simpler. I took a few small zip ties, daisy-chained them together to an appropriate length, and positioned them such that the interlock override lever is in a permanently-overridden position. The small daisy-chain of zip ties doesn’t interfere with anything and has enough slack that it can be removed without tools, if necessary for some reason. The zip ties are bright yellow so they’re obvious to anyone looking in there.

The effect is that the shifter now behaves as they used to in the 60s. You can’t shift out of Park without deliberation, but you can do so without the ignition on and stepping on the brake.

So, half a grand in parts and labor, before tax? Or a couple of zip ties? The difference will put lots of gas in the bikes. See you on the road.

Update, November 24, 2012: I’ve noticed that this is a popular post. Between the comments and the email, well, this is apparently a common failures. And here I just read in Fortune magazine about how hard Ford works to make sure their parts are reliable. But I digress. I simply wanted to add that my fix is working just fine to this day. Haven’t touched it. No problems.