Toyota Single Coil and Distributor Ignition Systems, with computer controlled advance and 5-pin ignitor

The most common stumbling block people come across with wiring up an engine conversion is the ignition system. Often a second hand loom is used or you are making a loom from scratch, and when you get to the ignition system - you can't for the life of you match up what the fudge is what!

So here is a quick little explanation of Toyota ignition system and 5-Pin ignitors that should answer most questions about them.

References..... these are the places/people I have to thank for this info:Ignition System Overview

This is basically the breakdown of the most common of toyota's ignition systems, where ignition timing is controlled by the ECU and the ignition system comprises of a single coil and distributor.

In short, what happens is the dissy is obviously spinning with engine RPM, and generating the variable reluctance (VR) signals "G1" and "Ne". Ne is the cam position signal from the multi-tooth wheel, giving the ECU the exact rotational position of the engine within it's cycle. G1 is a reference signal that the ECU can use to determine what cylinder the engine is up to.
The ECU reads these signals, then applies it's ignition advance according to its programmed ignition map, and sends the IGt signal out to the Ignitor.
The ignitor fires the ignition coil according to the IGt signal.
The ignitor also generates a return signal to the ECU - IGf - to let the ECU know that the ignition event was sucessful.

Pretty simple really.

So how does one wire up the 5 pin ignitor?

The really annoying part about wiring up a conversion, is a majority of Toyota 5 pin ignitors after 1989 have the plug as part of the housing - meaning there are no wire colours to go by. This is quite the PAIN.

So here are the pinouts, and most comon wiring colours.
Note that the metal case is the earth for the ignitor, so make sure it is bolted to metal (the stock brackets usually provide this earth)

1/ B-R: Coil Negative (output)
2/ B: Tacho signal (output)
3/ B-O: Ignition power (12V+)
4/ W: IGt (input)
5/ W-R: IGf (output)

How does one wire this all up with an aftermarket ECU?

Well - this is easy! Most of you would be using a Microtech/EMS/etc etc which are all quite capable of using the stock signals and ignition system. Here is the way most of these will hook up to this type of Toyota ignition system.....

Most aftermarket ECUs want both a "cam position trigger" and a "reference trigger". The Toyota dissy in this system provides these triggers with a VR (variable reluctance) signal with a falling edge trigger. This "falling edge" part is important, because the ECU needs to have the signal go a particular way for the internal circuitry to detect the very low AC voltage from the VR signal and interpret that as a trigger event.
Some aftermarket ECUs allow you to select a falling edge or rising edge trigger through it's programming software, but some want the signal to be one or the other without the option of change.

Here's what a trailing edge VR signal actually looks like:

Here's a rising edge VR signal

In the factory wiring configuration, the Toyota dissy provides a falling edge signal.

Wiring up the dissy side of things is pretty simple, but you need to pay attention to your particular ECUs wiring instructions.

Inside your dissy you will find something similar to this:
  • "Ne" sensor is your cam position sensor
  • "G1" is your reference trigger


For falling edge trigger - the pink wire is the signal, and the white wire is the earth. I think in some dissys the wires are yellow and white.... but in all cases the white wire is the earth for that sensor.
For rising edge trigger - wire up the sensors in reverse, ie white is the sensor, and pink/yellow the earth.

  • from the factory, Toyota wires the earth of each sensor together to make one earth wire. On most aftermarket ECUs i've played with, they have a separate earth for each signal. YOU MUST WIRE EACH EARTH SEPARATELY if your aftermarket ECU has a separate earth for each signal. You will screw up the signals otherwise.
  • shield the signal wires! Most looms you get with an aftermarket ECU (and all Toyota looms) have shielded wires for the dissy. You'll notice this as these signal wires are grouped together and covered with a metal braid and PVC jacket. *INSERT LINK TO PICK* <click on here<<<. Make sure the shielding covers as much of the signal wires as possible, minimise the length of unshielded signal wires as much as possible. This shielding protects the electrical signal from interference.
  • DO NOT EARTH THE SHIELD unless the wiring instructions for your particular ECU say to do so. Most will already have the shield sorted out in the loom already.
.... now that covers the input signals to an aftermarket ECU....

When you come to wiring up the ignition OUTPUT of your aftermarket ECU - depending on what ECU you have there are a few choices.
  • Some ECUs have in-built ignitors and can control the coil(s) directly. Thus you can remove the toyota ignitor.
  • Some ECUs want a "dumb" ignitor - meaning one that does NOT control dwell time. The Toyota ignitors DO control ignition dwell time, so you will need to use something like a Bosch BIM027 ignitor in this case.
  • If your ECU can be used with a smart ignitor (that does control dwell), so you can use the Toyota ignitor with these. Wire up the ignitor as per factory, but wire "IGt" to the ignition output of your ECU, and you wont need to wire up IGf at all.

Some points about Toyota DLI Ignition Systems

These work in virtually the same way that the single coil systems work, but they have multiple coil "packs" and instead of a distributor they have a Crank Angle Sensor (CAS). The most common examples are 7M-GTE and 4A-GZE engines.

Here's the system overview of a 7M-GTE:

The main difference between the DLI system and the single coil system is the ignitor. These are a special kind of ignitor that have extra inputs to determine which coil is fires. Notice in the system above the extra "G" signal and the "IGda" and "IGdb" signals - these are how the system knows which coil pack to fire. The two G sensors - G1 and G2 provide the "reference" signals to the ECU which the ECU uses to pick which coil pack to fire.
The ECU then ouputs the IGt signal as normal, but also outputs an IGDa and IGDb signal to the ignitor so that the ignitor can fire the correct coil pack.

This is a bit of a problem with aftermarket ECU's, because this ignitor cannot be controlled by pretty much any aftermarket ECU.
However, if your ECU has at least 3 ignition outputs, it *should* be able to control each coil via these three outputs and either 3 x BIM027 ignitors, or just one Nissan RB2x engine ignitor. (the nissan RB2* ignitor has 6 channels and is a dumb ignitor. You can use an SR20 one, which is the same but 4 channels).

NOTE: the 4A-GZE DLI ignition system only has two coil pack, and the one IGd signal.

Well i think i should have just about covered everything here that's worth mentioning.
If you read the Autoshop101 link up the top, there is a lot more in-depth explanation of the ignition systems. Autoshop101 is the king of info.