Originally Posted by Gerhard from PO.com

Ok,

I've been getting a ton of messages from people interested in knowing how to wire their 5th Gen Prelude after converting from the SS Auto to the 5 Speed Manual Transmission.

It seems that many folks are having problems with a lot of simple concepts in respect to automotive wiring. Such as:

- What is pin?
- What is a connector?
- What is a wiring harness?
- How do I find the Automatic Transmission Gear Position Sensor (ATGPS for short) and its harness?

The first thing you need to have to begin this work is the Helms manual for the 5th Gen Prelude. If you don't have it, then get it. Period. You need to be able to look at the pin-out chart for the ATGPS to do this job. (Please do not send me emails if you are too lazy to look things up in the Helms manual.)

Definitions:

PIN: (aka electrical contact) Pins come in both male and female varieties. The male side slips into the female side (obviously) creating an electrical connection or "conducting" current to complete the circuit.

CONNECTOR: This is the housing the holds a bunch of pins. On a Honda they are generally gray, but can also be black, blue, green, or orange.

WIRING HARNESS: This is the set of wires that generally connects one part of an electrical system to another part of an electrical system. Typically, a car will have a complete wiring harness for the engine bay that covers all of the electrical components and connection around the engine (et al).

RELAY: A device that responds to a small current or voltage change by activating switches or other devices in an electric circuit.

OPEN: An electrical term meaning that the circuit is open. An open circuit is one where current can not flow because their is an break in the wire or an interruption from a turned off switch, relay, etc.

SHORT: An electrical term that means the circuit is closed. A shorted circuit or "Short Circuit" is one where current is flowing between one or more points. An example of this is a closed switch: When the switch is closed it is turned to the ON position and current flows through it. A "Short Circuit" can also be when current is (for some reason) flowing somewhere it shouldn't be. An example of that would be dropping a long screw driver on the battery of your car and having the + (positive) and - (Negative / ground) terminals connect. (Resulting in a spectacular explosion or the destruction of your screwdriver and battery and God knows what else.)

Getting started:

Open the Helms Manual to Page 14-108:

First, the best thing you can probably do is to remove the Auto Trans Gear Position Switch (ATGPS) from the automatic transmission when you take it out of the car. [You can then cut off the switch and use the wires on the remaining portion of the harness (that was attached to the switch).]

In the Helms manual you will note that there is a switch attached to a wiring harness. That switch told the automatic tachometer to display which gear the car was currently in. It also told the TCM (transmission control module or "brain" for the transmission) what gear the car was supposed to be in.

Removing the ATGPS is done using the standard 10mm socket that most of the Prelude is disassembled with. Once you'd removed the ATGPS from the transmission, you need to take a pair of dikes (aka cross-cutting pliers) and cut the switch part off the harness.

Once you have the harness and switch separated you can then solder or bullet crimp the wires you'll need to connect together. [I HIGHLY recommend that you solder and heat shrink every connection. If you do not have familiarity with doing this, get someone to help you. Since this is going to be in the engine compartment, it needs to be durable.]

Using the ATGPS will prevent you from damaging the car's wiring harness by tapping into it using such things as bullet connectors, wire taps, and so on. The Prelude's engine bay wiring harness can only be purchased as a whole unit for about $500.00. So if you wreck it, it's going to cost you!

Hooking things up:

Look at page 14-109 in the Helms manual.

This view shows you where the ATGPS hooks into the wiring harness for the car.

NOTE: The male side is the ATGPS, and the female side of the connection is the car's wiring harness.

Now look at page 14-107 in the Helms manual.

This page shows you the actual pin-out view of the wiring harness for the ATGPS side of the connection (between the ATGPS and car's wiring harness).

So, if you are holding the ATGPS connector in your hand and looking at the pins, you would see what is at the top of page 14-107 (just pins themselves not a bunch of numbers).

What this does for you is that when I give you which pins you need to use, you'll look at the other side of the pin in the connector and find out which wire corresponds to that pin. [I don't remember what color the wire are, and some folks are color blind.]

Reverse - Backup Lights:

The reverse lights should be connected directly to the ATGPS harness by soldering wires to pins 3 and 9 using a male and female bullet connector.

The manual transmission has a backup lights switch with two connectors attached to it. These connectors are male and female bullet connectors. To properly create the connection you'll need your own bullet connectors and a piece of wire. Pin 3 is actually used for two connections, so you don't want to connect the bullet connector directly to the wiring coming off of pin 3. Pin 9 you can solder or crimp a bullet connector directly two as it's only used for reverse.

It turns out that the bullet connectors on the backup light switch on the manual trans are exactly the same as the ones for the LED (light emitting diode) array in the wing. I had an extra set of LED's... so I chopped off those connectors and used them. They are rubberized and a perfect fit.

How the reverse circuit works:

The reverse switch works by completing the circuit and energizing a relay that turns on the backup lights. Pin 3 is a 12 volt feed line that provides low level power to any circuit attached to it. Pin 9 is the side of the circuit that energizes the relay when power is applied to it. The reverse switch shorts pin 3 and pin 9 whenever the manual transmission is in the reverse gear, thus turning on the backup lights.

Clutch Starter Cut Off:

If you don't care about being able to start the car with it in gear, then you can solder the wire coming off of pin 3 to pin 1. The car will always start, even without you foot depressing the clutch.

If you want the car to not start when the clutch is NOT depressed, you need to run a pair of wires to the clutch [top switch] from the wires on pins 3 and 1 of the ATGPS harness. There are two switches on the clutch: one that works when it's fully depressed (starter enable), and one that works when the clutch is not depressed (cruise control enable).

What you need to do in this case is you need to run some decent 16 or 14 gauge wire from the wires on pins 3 and 1 thru the firewall and into the car where the clutch is. The most professional way to attach the wires to the clutch switches is to have gotten the connectors from the wrecked Prelude that you got your swap stuff from. Then you simply connect the two wires to the switch by soldering the wires you've run to connectors you've gotten from the wreck. [One of the switches has more than 2 pins, so you need to take a voltmeter and verify connectivity on the two pins you are going to use.]

How the Clutch Starter Cut-off works:

Pin 3 provides a 12 volt feed to the circuit. Pin 1 provides current to a starter cut-in relay that enables the ignition to energize the starter relay. When the upper switch on the clutch is engaged (peddle is down) the circuit is shorted and current from pin 3 flows through the switch to pin 1 allowing the car to be started.

Cruise Control Cut Off:

The cruise control circuit needs to be grounded for it to be active. So, this means that you need to ground the wire on pin 2 of the ATGPS for the cruise control circuit to work. So you need to run a wire (in addition to the 2 for the clutch cut off circuit for a total of 3) to the lower switch on the clutch from the wire on pin 2 of the ATGPS harness. On the other side of the lower switch on the clutch, you need to run a wire to any grounding point in the dash board area near the clutch.

How the cruise control circuit works:

This circuit is always turned on when the clutch is NOT depressed. The moment you put your foot on the clutch pedal the connection to the dash board area ground is interrupted and the cruise control turns off because the lower clutch switch is now open.

Once you've done all of the above your Prelude will work just like a factory 5 speed.

Gerhard
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