ECU Wiring

I know this topic has been hit a few times and I have read all the post but I have found some conflicting information so I just want to make sure I am doing this right. I am running a Microsquirt ECU so there's only a few wires. I will be using the DME relay- Fetch9 Solid State

Red- 12V Battery
Black- ECU Ground
Small Red- 12V Switched
Purple- Fuel Pump
Green- Tach


From my understanding leaving everything in there and accessing the 14pin connector in the engine bay driver side at the firewall these are the pins I need:

Pin 3- Use for 12v Switched
Pin 4- Use For Fuel Pump
Pin 6- Use For Oil Gauge
Pin 8 - Use For Coolant Warning
Pin 9- Use For Oil Warning
Pin 10- Use For Coolant Gauge

Tach will be attached to back of cluster
12v Battery to Battery
Ground I assume Engine or Battery Ground

Looks correct. For the tach hook up, you can tap into one of the connectors underneath the glove box. Cannot recall the wire color. Makes it easy as i assume you will be locating your ecu in the passanger footwell where the stock one was. I had to use an inline resistor for the tach to function properly with a GM ecu. Not sure if that is required with the megasquirt.

Personally, I choose to bypass the porsche dme relay system and fuse box all together, and instead used a seperate relay/fuse block for the ecm, fuel pump etc. Only used the 14 pin for the guages.

Thanks Leva, you've been a huge help!

There is a 4 pin flat connector close to where the Porsche ecu was located. The green/black wire in that connector is for the tach.

Once again you save the day, lol. Thank you!

CyCloNe! wrote:Once again you save the day, lol. Thank you!

Just in case Pin #4 Didn't work for me to activate the fuel pump (Green/Black wire), I ended up using Pin #5 (Black/Grey). Seems to have worked, also I am using the factory DME relay. Just in case someone sees this post later. Everything else was correct.

The green/black wire is tach signal to your tach. It would never work to activate the fuel pump.

Hotrodz of Dallas wrote:The green/black wire is tach signal to your tach. It would never work to activate the fuel pump.

In the 14 Pin Harness Connector at the firewall? Pin #4 is tach there as well?
I am using the Tach in the 4 Pin connector you mentioned in footwell with the Green/Black, that's working fine.

The 4 pin connector is what I was referring too. I use the ecu to trigger the fuel pump, not the 944 wiring.