Before we get full fledged into one of the first relocation's every 300zx owner should do lets talk about WHY.
The Power Transistor Unit, also known as the PTU, essentially controls spark by sending signals to the coil-packs telling the coil-pack when to fire. Here is the thing though, Nissan for some odd reason decided to mount the PTU on the passenger side (LHD) timing cover. Yes the Ptu fits in this location well however it is subjected to high amounts of heat and heat cycles. This overtime can cause the PTU to fail. Some of the symptoms of a failing PTU include intermittent misfire, misfire in 1 or more cylinders, and overall a rough running engine. If we take the heat away from this unit though it rarely ever fails, and that is why I always recommend the PTU as the very first thing anyone should relocate on their z32.
What Tools Will I Need?
-8mm Wrench (or 8mm Socket)
-10mm Wrench (or 10mm Socket)
-Razor (Box Cutter)
-Flat Head Screw-Driver
-PTU Relocation Bracket (or Temporarily Use a Ziptie)
1. We need to unbolt Ptu from its stock location. There are (4) 8mm bolts holding the ptu to the passenger timing cover. The top 2 are easy to get to, but the bottom 2 are a little harder to take off with a socket wrench and socket so i recommend using a close end or open end 8mm wrench for the bottom 2 bolts.
2. There are 2 main tabs and a plastic bracket that hold the ptu wiring as well as the engine temp plugs close to the timing covers. Now that you have unbolted the Ptu, pull the 2 tabs back to allow you to pull the section of wiring out of place. here is a picture for reference.
3. There is also a plastic type tab/bracket that holds the far end of the ptu wiring section. Use your flat head screw driver to lift up the top plastic tab to release the brackets grip.
4. Now that the harness is loose we need to separate the ptu wiring from the engine temp plug wiring (the engine temp plugs are the 2 plugs directly in the center and in front of the timing covers that plug into the coolant hard-pipe). We can separate the plugs wiring by using a razor blade to carefully cut the old electric tape holding both sets of plugs wiring together (dont go HAM, just lightly cut down the length of the loom about 8-12 inches. Just enough to give the ptu enough length to route forward beside the radiator).
Here is what it looks like once you have carefully cut through the electrical tape.
5. Now that the 2 sections of wiring have been separated, we need to re-wrap the wires with electrical tape. For simplicity's sake you can tuck the engine temp plugs wires back into its original sheathing and re-wrap it with electric tape. Dont forget to wrap the exposed PTU wiring.
6. The brunt of the work has now been completed. Next we need to unplug the PTU from the harness. The reason we need to unplug the ptu is because it will make the next step much easier.
7. Once the Ptu is unplugged, we are going to feed the plugs under to the nose panel area. there is a little open section between the radiator and the headlight tray, thats right above the intake pipe on the drivers side that i circled below for you all.
8. Feed the PTU plugs through this area and pull the plugs through to the other side.
9. Alright now just plug the Ptu back in, and use a Ptu relocation bracket to secure the Ptu in place off to the right slope of the nose panel area. (If you dont have a relocation bracket you can temporarily ziptie the Ptu in place).
10. Now its time to secure the harness by the timing covers in the tabs and plastic bracket (the ones we undid at the beginning). and clean up the timing cover where the PTU used to be.
11. Take a step back and look at your work.
And thats all for this relocation. Hope it went smoothly for you as it has for me.
As always have an amazing day and stay driven.
By: Ocean Nickel