In desperate need for a RK112 one button fob | Ford Explorer Forums - Serious Explorations

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In desperate need for a RK112 one button fob


New Member
October 12, 2017
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Deventer, The Netherlands
City, State
Year, Model & Trim Level
1997 Explorer 4.0L V6

My car hasn't been able to start for a few months now because my Bosch RK112 one button fob broke beyond repair. I have tried bypassing the Bosch VIM171 immobilizer with no success.

I took it to a local garage which suggested me to buy a second hand FOB so he can reprogramme it to work with my car. The only problem is, I can't seem to find any Bosch RK112 fobs anywhere for sale.

Who can help me out? :(

I own a Explorer 1997 SOHC 4.0 V6 *Bosch Immobilizer*

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What have you done to try to bypass it? To what extent is the vehicle operational? Does it crank (starter working)? Do you have spark? Do you have fuel? Did any of these functions begin to work due to your bypass attempt?

I have never seen one in person, but based on a couple pictures, my best guess is the following:

It looks like a factory setup so no wiring splicing to install it, instead the wiring harness to a vehicle computer plugs into it, then a cable from it goes to the computer. This suggests that you could run the harness direct to the computer without it. This assumes it is the same as a US Explorer except added components for this Bosch module. If the harness is too short to reach the computer due to being a different length than the US version, then you might need to find the longer US version or graft the security module harness to computer, onto the harness going into the security module, to make it long enough.

It also seems that it might connect to a fuel pump disabler module mounted on the tank which you would need to jumper around, dropping the tank to do so.

All of the above is only speculation. I could be wrong. I have no idea how to find a new fob anywhere near Deventer, or anywhere else for that matter except to keep checking eBay in case one eventually goes up for sale.

rez123, I have probably edited and added to my post since you last read it. I seem to edit a lot. :cool:

What have you done to try to bypass it?
I found a guide which stated this:
To neutralise the immobiliser
Join together 10 and 13. To ensure continuous spark at distributor.
Join together 9, 15 and 16.
Join together 11 and 7.

Unfortunately this is written for a VIM 125 model so I tried my best to make it work for my model which didn't work.

( )

To what extent is the vehicle operational?

I can put the car in RUN so everything electronic related turns on, it also cranks but I've read the Immobilizer controls PCM, Spark and fuel pump.
Does it crank (starter working)?
Do you have spark?
I'm not sure, I've read the immobilizer also disables spark so I don't think I have spark
Do you have fuel?
Did any of these functions begin to work due to your bypass attempt?
Not that I've noticed.

I've read a guide online that it's possible to reprogram a new Bosch Key so I think that's my safest bet.
Before my bypass does more harm than already is done.

Problem is I can't find any of these Bosch keys online, not separate and not with a paired Immobilizer.

Have you tried asking for the key at junk/salvage yards?

Is there any idea what failed on the key you have? Perhaps it can be cannibalized for unique components and the circuit recreated in a project box that stays with the vehicle instead of in your pocket?

I'll contact some junk/salvage yards tomorrow, thanks for the advice!
The key is absolutely beyond repair, I brought it to a locksmith which confirmed this.

Fingers crossed a scrapyard has a fob laying around!

A locksmith can only tell you whether someone with locksmithing skills can repair it. Did it suffer direct physical damage? I'm just wondering if it's something relatively minor like the soldered on switch mechanism broke and the locksmith doesn't solder or use a multimeter to determine that the switch isn't working.

The button switch came off, which i tried to solder back on a few times which luckily worked for a month or two. But because i've soldered it too many times some circuits on the board are damaged due to the heat.

I think all the diodes etc are still working so all the necessary parts could be salvageable. I think my locksmith which is specialized in reprogramming new fobs didn't want to deal with the hassle. Any idea where I could take this to, some kind of specialist? I have non experience in this kind of stuff.

I have no idea where to take it in your region, would ask in a Dutch electronics or automotive forum, the latter possibly also having more ideas about where to find a replacement since AFAIK, they aren't used much if at all in the US where most of us are located.

To my surprise I've found a linked PAIR on ebay uk for sale, exactly the same remote and immobilizer salvaged from a explorer! I didn't hesitate a single second and bought it straight away for only $200!

Thank you so much for thinking with me!

Hope it works out. What did it cost? Then again an eBay sale when there aren't any others for sale, doesn't tell us much about market value.