I hope this how-to helps those of you who are interested in doing the swap.  I request that this document not be modified in part or full.  If there are errors or anyone recommends extra information let me know so I can update this. 

-Adam   neon98ky@hotmail.com

Dodge Neon 95-99 Tachometer/Speedometer Swap

Required tools and materials:

-        Fine tip soldering iron

-        Fine soldering wire

-        22-26 gauge insulated, solid-core wire

-        Star driver (to take apart cluster)

-        Time

Disassembly:

            I will assume that you all know how to remove the cluster from the car.  If not, simply pop the top of the dash off and remove the four Phillips-head screws that hold the cluster into the dash. 

Begin by removing all of the star-headed screws from the backside of the cluster.  There will be some screws that hold on a thin paper-like material that has words printed on to it.  My guess is that this piece is for protection and as a guide to assist replacement of the light bulbs in the cluster.  I never bothered putting it back in.

After you get these screws out, remove all of the screws that hold the PCB (printed circuit board) onto the rest of the cluster.  In the center of all this mess there is a ribbon plug (I think it has something to do with the odometer?).  Once you get the screws out and the plug unplugged.

Modification:

            The areas of the board I will focus on are highlighted above with different colors.  This perspective is as if you were looking at the cluster from the front and could see the PCB (so it’s really the unexposed side of the board when it’s together.)  The red shaded area is the chip that drives the motor for the tachometer.  The purple area is where the posts of the motor actually contact the board.  The blue area is the chip that drives the speedometer, and the green area is where the posts for the corresponding motor contact the PCB.

Breaking Existing Connections:

            The first thing you have to do is break existing connections between the driving chips (red and blue areas) and where the motors are driven from physically (I’ll just refer to these as post locations.)  I used an exacto knife to break the traces in the board (just cut them and twist the blade tip around a bit.)  The first picture below is of the speedometer post area (green above) and the second of the tachometer post area (purple above).  If you look at the corresponding holes in the PCB you will see where the posts go through the board and make contact.  The breaks in the traces I highlighted in red.

            You’re probably noticing by now that the tachometer post location (bottom picture) looks a little different than the speedometer area (top picture).  There are two sets of holes because the same board is used for both tachometer and tachometer-less clusters.  In a tachometer-free cluster the left 4 holes would be used, but since this is a tachometer cluster the right four are used.  Also note that the orientation of the holes has been rotated 90 degrees.  Yes, this means that the motors for the needles are oriented differently.  Does that matter? No. 

Making new connections:

            Simply put, all that’s left to do is run wire from the driver chips to the post locations.  To do this use solid core wire (I used wire from CAT-5 networking cable, although at points the insulation melted), a fine tip soldering iron and fine soldering wire.  Pay close attention to where you run the wire for these connections—There are obstacles that needed to be avoided in order to prevent pinching of the wires when the board is put back onto the cluster. Carefully make the connections shown below, connect corresponding wires to each other.

Connect from speedometer chip area (blue area from key above)

to Tachometer post area (purple area from key above):

and then tachometer chip area (red area from key above)

to the speedometer post area (green area from key above):

            Once you’ve made the connections, you should end up with something that looks similar to this:

Testing:

            When you are done with all the wiring, put the board back onto the cluster, put back in the screws and don’t forget to reconnect that plug in the center.  Plop the cluster in the car and take the car for a spin.  If all connections are good, you’ll be scratching your head trying to figure out your RPM and speed. 

The needles will sweep the correct amount at this point—but you’ll have to surely remove them if you ever want to put on a custom face.  When you do remove them, just replace them as you would when installing an indiglo overlay.  Note your warm idle—then when the time comes to replace needles let the car run to a warm idle and replace the needle.  The speedometer you can set by driving along at a known RPM/speed and setting it at that point.  When having a custom face made (or doing it yourself) just remember to get the angle between each mark to be the same as it originally was and you’ll be fine.  Scaling of the face has no effect on the accuracy of the needle.

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