Wiring a Late Series PTU into your Early Series 300zx

by Robert Sidaway on February 03, 2024 Categories: 300zx How To

Updating a late series PTU into your early series 300zx is a very common repair, almost to the point it should be considered preventative maintenance. Please take care with installation is failing to match the correct terminals on your new PTU to the correct wire on your EFI harness can result in damage to the PTU, the ECU, the EFI harness, or all of the above. 

PTU kits can be purchased HERE with the option of wire in connectors, or a plug and play harness adapter.

Your new, late series PTU will have temrinals labelled E1 to E6 on one side, and terminals labelled I1 to I6 on the other as shown below. 

The terminals on the E side are to be connected to the signal wires for the coil packs, and the terminals on the I side are to be connected to the wires running back to the ECU. Terminal G is the ground, and should be wired to the earth wire in your EFI harness. 

The Engine side of your Early Series wiring harness has the 7 pin PTU connector. Each of these pins is labelled 1 to 7 on the connector. The table below shows which terminals on the new PTU match which wires on the original connector. 

E1: 1 (Black)

E2: 2 (Red/White)

E3: 3 (Red)

E4: 4 (Red/Green)

E5: 5 (Red/Yellow)

E6: 6 (Red/Lilac)

G (located on the I side of the PTU): 7 (Black)

The Input side of your Early Series wiring harness has the 6 pin PTU connector. Each of these pins is labelled 1 to 76 on the connector. The table below shows which terminals on the new PTU match which wires on the original connector.

I1: 1 (Lilac)

I2: 2 (Lilac/Orange)

I3: 3 (Lilac /Red)

I4: 4 (Lilac/White)

I5: 5 (Lilac/Blue)

I6: (Lilac/Yellow)

Perform a continuity test to confirm you have installed the new connectors correctly before attempting to start your vehicle.

Continuity should exist between the following terminals

PTU I1 & ECU 1

PTU I2 & ECU 2

PTU I3 & ECU 3

PTU G and Ground

PTU I4 and ECU 11

PTU I5 and ECU 12

PTU I6 and ECU 13

PTU E1 and ignition coil 1

PTU E2 and ignition coil 2

PTU E3 and ignition coil 3

PTU E4 and ignition coil 4

PTU E5 and ignition coil 5

PTU E6 and ignition coil 6