By Keith Lee (aka Keith) (Most of the article was written by Dan aka coil222)
Last Updated

Special thanks go to;

• Dan (a.k.a. coil222) - for allowing me to post his installation document from www.preludeonline.com and for his helpful emails.
• Stanley Chan (a.k.a. jbx) - for helping me install this unit.

NOTE -

Dan wrote this whole article practically. I just used it as a guide line and took some pictures of my installation. Comments in italics are my comments that I have added.

• You Need
• Install
• Comments

Introduction -

This little gadget is basically a toy. It provides fun stats such as your vehicle's rev, speed, tripometer, battery voltage and with the optional G-Sensor, you can obtain horsepower, lateral g-forces, acceleration, braking and lap times.

You Need -

• 10mm socket wrench
• Electric tape
• Wire stripper/pocket knife
• Wire cutter/crimper
• Soldering iron/solder or solder-less crimp on connectors
• Optional: extention wire

Install -

Before doing any of this you should remove the negative terminal from your battery for safety.

First off, get to your ECU. This can be found under the passenger side carpet under the dash. Remove the plastic kick panel, the carpet will just pull right up and then you have 4 10 mm bolts to remove to get at your ECU.

You can then lift up the Panel the ECU is attached to. I'd recommend propping it up with something. (I used a screwdriver.) With the panel lifted you'll see something like this:

Comments -

On a Prelude you have 5 wires to connect to the ECU. On the RSM harness you have 9 wires. I have provided color codes for my car (99 base) Double check the Wire's Location on the wiring chart to be sure it's the right wire before you cut - Color codes may have changed between models/years.

• Red: Ignition power - connects to yellow black wire on the ECU.
• Yellow: RPM Signal - connects to yellow wire on ECU.
• Black: ground - Connects to a brown/black wire in the ECU.
• Purple: Speed input - Connects to blue/white wire going to the cars wiring harness.
• Pink: Speed Output - Connects to the SAME blue/white wire but goes into the ECU.
• Blue/Brown - not used on our cars
• White - RPM output - can be used to trigger (but not to power) something, for example a shift light set to illuminate @ a selectable RPM.
• Grey - Speed output - can be used to trigger (but not to power) something @ a selectable Speed.

Use wire-cutters to cut the wires, strip them down and splice in your RSM wire. I'd suggest using a soldering Iron rather than crimpers. Then cover your connections w/ electrical tape. After connecting these 5 wires into the ECU we turned on the car to test - Success! Run your cable to the left behind the dash or under the center console, put the ECU back in proper place (be careful not to catch any wires in the footrest) and re-attach the trim panel to your car. Here are some pictures of what wire tap in connectors look like and Stan installing it in my car.

We now have Power and nothing is smoking yet. The G sensor - which is optional will connect into the RSM also, it just plugs right into the RSM itself, not the ECU so it is very easy to add later if you do not buy it at the same time as your RSM. This sensor is usually an extra $40-50.

Now we mount this baby. It has an optional stand, which is exactly the same as your V-AFC stand. This attractive stand is usually an extra $15-20 but if you can make your own, great. I mounted mine right on the Steering Column. Kind of blocks your view of the speedometer and the tachometer but this device provides digital readout for both. (Speed in KPH though) 1 MPH = 1.609 KPH I routed the cables though the cavity for steering column. Nice and out of site.

Mounting the G sensor is easy, just find a nice flat surface, stick it to the sponge it comes with and stick that to your car. I put it under the center console to keep it out of site. The purple/white/black wires sticking out are not used.

Now for programming:
You'll need to know your metric system well to get this working. I don't so I used this HELPFUL Link: http://www.convert-me.com/en

We have to input the estimated weight of the vehicle to get accurate horsepower readouts.
The formula for this is:
Vehicle weight + driver weight + cargo weight + gas in liters (not sure if 1 liter of gas = 1 kg but that's how it is in the manual).
Easy enough, I came up with 1472 kg, call it 1470 kg.
I'm not satisfied by the manual's explanation of 1 liter of gas weighing exactly 1 kg so I did some dirty work and found out on my own. Cited from: learningnetwork.com - 1 gallon of gas weighs 6 pounds. 1 gallon = 3.785 liters, so 3.785 liters = 6 pounds. 6 pounds is 2.722 kg, so 3.785 liters = 2.722 kg. Divide both sides by 3.785 and you are left with 1 Liter = .719 kg - so Almost 1 KG. Our 16.9 gallon gas tank is 64 liters, so this would weigh 46kg.

Here are some numbers that will help you.

• Stock base prelude weight manual trans - 2954 lbs = 1340 kg
• Stock base prelude weight SS auto trans - 3009 lbs = 1365 kg
• Stock Type SH prelude weight - 3042 lbs = 1380 kg
• I weigh 125 lbs which is 56.7 kg - call it 57
• My speaker box weighs approx 100 lbs = 45.36 kg - call it 46
• They say a C/F hood saves around 40 lbs over a stock one, 40 lbs = 18.14kg.