Upgrade to PRW-2 Ign. Control Module (Power Transistor Unit)

So this one is pretty simple. I'm not even going to post pics or wiring diagrams because the Z31 wiring is the same across all years in this modification as far as I'm aware. michaelp said he would take pictures next time he does the upgrade to a customer's car. So I didn't bother taking pics. Thanks to michaelp for some help in sourcing diagrams because I was lazyfaced.

This guide pertains to the following item, it has a number of names:

• Power Transistor Unit
• Ignition Control Module
• Ignitor Chip
• Ignition Transistor

It is the transistor that charges/discharges the Ignition Coil.

It can be found on a number of Distributor equipped Nissans

• Altima
• Sentra
• Pathfinder
• Maxima
• many others, I'm sure.

The one you will source looks like this:
(PRW-2, but there is also a similar looking PRW-1A)



On the Z31 harness located on your drive strut tower behind the headlight (where the main ignition components are), you will find your current PTU. It probably looks like this:



The issue with the newer PRW-2 is that there are two wires that have been flipped, or two contacts that need to be swapped on the Z31 harness.


The procedure is simple. All you need is one of these:



THE ONLY WIRES YOU ARE SWITCHING ARE THE BLACK and the GREEN/WHITE wires.
THE COMMON WIRE BETWEEN PRW-2 EQUIPPED CARS and Z31's IS THE BLUE WIRE. LEAVE THAT WHERE IT IS.

You must remove the black housing clip on the back of the z31 harness grey connector to expose the seals on the back of the wires. All you need to do back here is to be able to see the seals. You do not interact with the seals or poke them at all. You need to remove this black housing clip to be able to pull the wires out. That's all on this side.

Now insert the safety pin into the small rectangular hole just above the head of each of the contact pins from the INSIDE of the connector. You simply lay the pin flat on the top of the connector contact, and slide it in until it stops. Do not force it in. It will slide off. You simple slide the safety pin in until it stops, and gently pry downwards so the retainer inside the connector is moved up and away from the contact pin, while GENTLY tugging on the back of the wire. DO NOT try and use pin removal tools from generic tool kits or whatnot. They are too large, cumbersome, flimsy, thick, or not long enough and bottom out on the connector body.

It takes just a gentle pry and pull.

Once you remove the black wire and the green/white wire, just shove them back into the opposite sockets, and put the black connector back-housing onto the connector again to seal it all up. Drill some holes and weld some 5mm nuts onto your ignition coil bracket or just zip tie it down onto a piece of metal (it needs a heat sink to remain cool) and away you go.

You can refer to the pathfinder and the z31 PTU diagrams to see how the power transistor "collector", "emitter", and "base" terminals are wired up. michaelp might have them, I don't remember where I put them. But if you do decide to look at those diagrams, turn the Pathfinder one upside down to make it less confusing. Nissan changed the orientation of the connector locking tab so it may confuse or cause you to wire it up incorrectly and get no ignition at all.

Things you might experience from doing this mod:

• improved ignition response (immediately noticed this)
• improved idle
• improved timing control/stability (immediately noticed this)
• improved coil saturation/discharge
• improved improvements.

I know I experienced at least 7 out of the possible 5 I've listed there.

Enjoy, and happy ch00ning.