Connecting A Monit Wheel Sensor To A Non-Monit Rally Computer

This year I will be navigating in at least one car that is fitted with a Monit wheel sensor, but where I will be using a rally computer not manufactured by Monit.  As a result, it will be necessary to have the proper interconnection between the wheel sensor and the rally computer.  Therefore, I have recently fabricated such a conversion cable that will serve this purpose.

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My Monit Wheel Sensor Conversion Cable

My initial problem is to be able to connect to the existing Monit wheel sensor in Dan Allven’s 1961 Volvo PV544 for our participation in the 2017 Rallye Monte Carlo Historique.  To assist me, Dan sent me some pictures of the interior cable end of the Monit wheel sensor in the Volvo.  One such photo is shown below.

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Monit Wheel Sensor Cable Interior Terminal Plug

The cable coming from the Monit wheel sensor has three wires whose functions are as follows:

  • Orange – Positive Wire (5 V)
  • Black (Green) – Ground Wire
  • Blue – Pulse Wire

I contacted the Monit odometer folks in New Zealand and I got an informative response from Mr. James Holder of Monit Limited.  He wrote that the plug on the wheel sensor was a Molex brand Micro-Fit 3.0 connector.  It has four connections arranged in two rows with two columns.  Mr. Holder warned me that the crimping tool was very expensive if I wanted to make up a cable myself and that it might be more cost-effective for me to buy an extension cable that they have for sale which has a male connector on one end and a female connector on the other end.  Presumably I could cut their extension cable to give me a conversion cable that is almost ready to use.  However, I already had the needed crimping tool from some previous work that I had done with my Terratrip 202+ rally odometer.

I then acquired the needed Molex Micro-Fit 3.0 male plug connector with fittings and made up my conversion cable.  The Molex Micro-Fit 3.0 male end on my conversion cable is shown below.

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Molex Micro-Fit 0.3 Plug With Male Connectors

If you look carefully at the above photo, then you will see that the upper two “squares” have one chamfered corner each.  This means that there is only one way the Molex Micro-Fit 3.0 connectors fit together.  I could not see the orientation of the chamfered corners in the other end of the Monit wheel sensor connector cable in Dan’s Volvo, so I made no effort to try to match colors with the Monit cable.  I decided that it was easy to install four different color wires in each of the four positions of the connector and I’ll match the purpose of each wire when I get access to Dan’s Volvo. It will just be a matter of being careful and paying attention as I know the purpose of the wires going to all of my rally computers/odometers.  I know that I will have one extra wire that I will tape off, as I only need the three active Monit wires.

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Four Connecting Wires Provides The Maximum Flexibility

I realize that perhaps not many people have a need to use a Monit wheel sensor with some other rally computer or odometer, but I thought that I would share my experience with those that do, to make their work easier.

If anyone wishes to get more information about Monit wheel sensors, then go to their website via the following link:

www.monitrally.com

If you have any questions or comments about making up a conversion cable for a Monit wheel sensor then leave a comment below or you can send me a private email message at the following address: shanna12 at comcast dot net

 

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2 Responses to Connecting A Monit Wheel Sensor To A Non-Monit Rally Computer

  1. Mike Mazoway says:

    That is basically what we did to match the Alfa sensor on my Subaru to your Timewise computer for Covered Bridge. The big difference is that I use inexpensive four wire flat trailer plugs for the interface.

    • Hi Mike,
      You are right on. The trailer plug approach that you used is simple and easy to implement. You put that interconnection cable together in about 5 minutes at the Covered Bridge Rally while working in the dark in the parking lot with a small flashlight. In addition, parts are available at any automotive store. The connector plug style that Monit uses is considerably more difficult to work with. The advantage for Monit is that the connection to the Monit rally odometers is quite small which allows Monit to provide a compact odometer that is easy to mount almost anywhere.
      Steve McKelvie

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