i'm looking to wire the Haltech CEL output to the stock CEL on the cluster. has anyone done this before? i would think the CEL would trace back to the stock ecu harness? but i couldn't find anything on the ecu pinout. is the only option is run wire directly from ecu to the back of the cluster CEL?

 

You need to tap into the orange / black wire that comes out of the electrical load unit.

 

that's the unit above the ecu? how do you even get to it? can't even see it with the HVAC blower in the way.

 

I wired mine to the exhaust overheat light on the center console. Chris Ludwig provided the instructions for me but I can find the info if your interested in that.

 

I pulled the gauge cluster and got easy access to the x15 plug and wired it to the orange/black wire. Works great now.

 

I too am trying to do this.
Myself, im having trouble as I am wiring a series 8 and my OEM diagrams are all in Japanese.
( I am running a haltech )
Could you tell me please if you are earthing this orange black wire to activate the light? ( I believe that is what the haltech will do to if I assign a wire to do so )

the series 8 wiring is fairly different.
the factory ecu plug has an assigned pin for engine faults, just it is a 1v signal. ( I think this is what the power fc will send ) but that will only help people with that ecu maybe.
Pin 4AI. see snip of diagram.

Your method obviously skips all the associated wiring in between, ( the hidden and hard to get to ecu )
I do not think the earlier fds had such a pin.
I have also read on this forum that s8s have no engine check light...
any help would be appreciated,

 

the US FD's have a couple extra parts, the BAC valve, EGR, and the check engine light, so they run out of available pins. they then add a little magic box, the E/L unit, and run the Headlight switch, Blower Switch, Defroster switch, and CEL to this E/L unit, and that frees up a bunch of inputs on the ecu for the add ons.

by the time they get to S8 all of that malarkey is gone. i'm under the impression that S8 has a Check engine light, although ive never seen it.
my notes show that FEN = Fault ENable, on the US cars that sends the code number to the E/L unit which then can drive a bulb