I've got an s5 TII, and when I removed the stock ECU and harness. There was some sort of plug with wires that plugged into the stock ECU but wasnt part of the engine harness. It came from somewhere under the dash. Since a stand alone ECU replaces the stock ecu and harness, what to do with that plug left after the stock ECU removal? Anyone know exactly what its there for and what it does?

 

When Mazda did the cooling system recall; it included a jumper cable between the engine harness and chassis harness, and also went to a newly included fan
control black box attached to the rear of the stock ECU.

This box with an unused single wire connector on it, is the FAN MOD BOX that many people talk about.

Later RX-7s or replacement engine harnesses has this jumper built into it .

 

No not just 1 wire. A whole group full of wires. Comming from under the dash into the ECU.

 

Chuck is thinking FD, not FC . That plug is the interface to the front harness for some things - it's all documented in the shop manual/wiring diagram. I think that may have the wiper control, cruise control, etc. stuff in it.

Dale

 

Ignition coils, electric fan, auto trans (J-Spec), and other stupid things like clutch switch and aux lamps (dunno why)...

Ignitions coils is the big one.

Wipers go through a crossover harness from the engine harness to a plug in the passenger side kickpanel.
Same goes for the water temp sensor to instrument cluster.

You can ignore the plug.
I usually tap into the ignition coil wires from that plug when I get lazy and don't want to run the (Haltech) wires through the firewall again.


-Ted

 

Hey ted, that sounds good... hell why not tap right into the coil wiring if its right there where you need it. Can you tell me what wires to look for and to what coils they go to.

 

It's a question on shielding.
It's recommended to use the Haltech wiring, cause the shielded wire is intact.
If you're going to use the existing stock FC wiring, make sure you ground the shield!
I had run into some RFI problems once, and grounding the shielding fixed this problem.


-Ted

 

Alrighty, gonna just wing it on this one...

There has been some problems with the ignition...something about interferance on the E6X. Could that be due to using stock wiring with no sheilding and not using the haltech wires with sheilding?

James