fusion645

I have a question to all. On the main relay which wire is the "switched hot" for the ECU off the main relay????

fcm

MM&Y of car?

The switched power for ECU off the PGM-FI Main Relay is the same lead as power for the fuel injectors, mostly it is a yellow/black but can also be a black/yellow, [96-98 Civic].
If the injectors are getting power then that output is working.

What is it you are trying to do/find out? 94

nsxxtreme

If I remember correctly the ECU switches the main relay on not the other way around.

But I haven't looked at those diagrams in a long time so I could be wrong.

fcm

Your kind of right, the ign, switch turns on the PGM-FI Main Relay, [injector relay] the injector relay supplies power to the injectors, a few engine sensor/valves, and a 12V+ "signal" to the ECU/ECM and power to the fuel pump relays coil, the ECU/ECM supplies the fuel pump relays coil with a ground energizing it, the same power that turns on the injector relay, [injector relays coil] is also the fuel pump power lead, [going through the fuel pump relay]
There are 3 fuses associated with the PGM-FI Main Relay, the switched one, [hot in run and start] that goes to the injector relays coil, [other side of coil is grounded to chassis] and as mentioned it is also power for the fuel pump, the 2nd fuse is a constant power, [hot at all times] it goes to the input of the injector relay, it's output supplies power to the injectors, ECU/ECM, engine sensors/valves and the fuel pump relays coil, the 3rd fuse is a switched power, [hot in start only] it is a "back-up" power for the fuel pump relays coil during cranking to start.

So long story short, yes there is a switched power from the PGM-FI Main Relay to the ECU/ECM, no it does not turn on the ECU/ECM it is just a signal, yes the ECU/ECM turns on the PGM-FI Main Relay, but only the fuel pump relay.

For those that still do not know, the main relay, [PGM-FI Main Relay] is actually two relays mounted to a small circuit board inside of the case referred to as the main relay, or correct name PGM-FI Main Relay, [programmable fuel injection main relays].
Problems with PGM-FI Main Relay are common, mainly on older Honda/Acura, the fix in most cases is very easy, here are three links that may help...
http://techauto.awardspace.com/mainrelay.html
http://www.tegger.com/hondafaq/mainrelay.html
http://www.tegger.com/hondafaq/mainr...ion/index.html 94

nsxxtreme

Ya looks like your right. Haven't looked at that diagram in a while.

If the original poster is looking to create the end all be all alarm kill with this, I highly recommend still layering your kills. This is a very easy thing to beat contrary to popular belief. But it does make a decent kill just dont have it be your only kill.