ECU and Wiring

1986 TransAm.

A New Zealand Based Site.

E.C.U and Wiring Page.

		The system I have chosen is based on the Bowling and Grippo Megasquirt. This is an open source project that has matured nicely with numerous success stories. Because I live in New Zealand buying the original Megasquirt PCB's and components was a) Expensive due to the, then, silly NZ - US exchange rates and b) A pain in the arse getting stuff shipped to way down under! Having had extensive experience in the electronics field, about 20yrs, and done a few Microprocessor projects in the past I decided to lay out my own PCB's and source components more locally. For this I used a very old version, 1.0, of Protel for both the circuits and PCB's.

The system I have chosen is based on the Bowling and Grippo Megasquirt. This is an open source project that has matured nicely with numerous success stories. Because I live in New Zealand buying the original Megasquirt PCB's and components was a) Expensive due to the, then, silly NZ - US exchange rates and b) A pain in the arse getting stuff shipped to way down under! Having had extensive experience in the electronics field, about 20yrs, and done a few Microprocessor projects in the past I decided to lay out my own PCB's and source components more locally. For this I used a very old version, 1.0, of Protel for both the circuits and PCB's.

The main ECU controller PCB I designed fits the same dimensions as the original with a bit tacked on the side to fit a locally available Aluminium box from Dick Smith Electronics. Other differences include vertical mounting of the driver FET's utilising the box as a heatsink and inclusion of the Flyback circuit that was originally a separate optional PCB (This is to enable use of low impedance Peak and Hold injectors if needed).

Because I was sourcing the Microprocessor, and most of the other components, from Farnell, Australia, I would need to program the chip from completely blank. To do this I built a serial interface programmer based on the open source Willette programmer circuit.
Again, starting with the open source circuits, I also designed PCB's for the on-bench simulator and under-hood power/sensor distribution and relay PCB.

Circuit Diagram.

The Protel circuits and PCB files can be found here if you have Protel, otherwise I have also converted the circuits to PDF here. Also included in the Zip files are under-hood diagram and ECU - Relay PCB harness details. Here's a Picture of the Relay, Programmer, ECU and Simulator. A Source Code editor and compiler can be found at P&E Microcomputer Systems.

Here's the engine bay wiring diagram. Drawn more for engine bay layout than ease of viewing. Original wiring was tapped into wherever possible to minimise looms. I am also sharing the original Coolant Temperature sensor with the GM ECU so had to modify the code using the utility EasyTherm to rebuild the lookup tables. The original MAP sensor in this car is a 1Bar unit but for future proofing I have opted to use a remote GM 2Bar sensor for this install.

Engine Bay.

Here's a Pic' of the ECU mounted above the Passenger's right leg. Ancient Win95 Notebook is run from an inverter plugged into the lighter socket for tuning.

ECU Closeup - Relay PCB loom runs through the firewall on the drivers side. Also fitted a heavy earth to the Gearbox.