Subaru I88 V10 plug-in Aux-8 Shift Light

[Cnstman]

I hooked up an autometer shift light to my Subaru I88 V10 plug-in on Aux-8 (car has no TGV's so I was not using Aux-8). I used a relay, so the I88 is just providing a ground to trigger the light. It seams to work fine, when I do a test on command ( I have not ran the engine since the install to confirm 100% though).

The weird thing is when I put the key in the accessory position the light turns on. when the key is in the run position its off. Why would this be? We turned Aux-7 off and I have Aux-8 set for a GP output now with Low Side driver. Any ideas?

Thanks!

[Guest]

Good morning,

That sounds a bit odd. Normally the ECU will only power up when the key is in the ON position. On your ECU there should be an LED that lights up when the ECU has power, it may be worth checking the status of this LED with the key in various positions. It is probably going to take some testing with a multimeter to work out what is happening.

Where is the power supply for the activation coil of the relay coming from?

Scott

[Cnstman]

the power for the relay is wired to the switched power at the radio harness.

It does not really bother me that it does this as I rarely sit in the car with the key in the acc position. Just wondering why it would to it.

[Guest]

One possibility is that the relay is back feeding through the relay and supplying power to the ECU. Most radios I've seen use a battery and accessory position supply. If it does start to bother you I would try changing the relay coil power supply to a power supply controlled by the main relay.

Scott