AIStang

I apologize for the double post. I posted this in the General discussion sub forum and reading the description I noticed that forum said for non technical.

New poster bobble.

Ok I am cleaning up the wiring in my American Iron 2000 Mustang.

The car has a 4,6 Modular motor in it with a bunch of mod and a stock wiring harness .

I have a factory wiring diagram reprint and have been cleaning up the mess of a harness the previous builder had under the dash bar.

The car has none ,I repeat none, of the below.

No Lights -- other than brake lights
Door locks
Wipers
Horns
Window defoggers

Ok you get the idea.

Only the engine controls that the PCM controls, antilock brakes and brake lights need to work.

My question is do I need the GEM?

On the wiring diagrams I don"t see a connection to the PCM. I know the instrument cluster is linked to the PCM along with the PATS and the GEM is linked to both of those.

It appears I could just remove the GEM and as long as the PATS was disabled with a tune the PCM would still function properly.

Does anyone on here really know about the GEM and it's interaction with the PCM?

Thanks

dawson1112

As far as I know the GEM (Generic Electronic Module) controls multiple functions: wipers, window switches, convertible top, airbag power, datalink, etc. You may loose the ability to communicate via an OBDII connection. There should be a fuse in the power junction under hood that you can pull that kills the GEM an check for engine functionality. Fuse number 7 I believe, GEM/interior lights.
I don't think the relation ship between it and the PCM is important for starting and running , only for communication of the OBDII diagnostics.

unitedwestang

Few months ago I was chasing a battery drain which ended up being associated with the GEM. Thought I was screwed. Until I found someone else who had the same problem on another forrm and all they did was pull the black and white wire (IIRC, defintely could be remembering the wrong wire). They said they had been running it for years like that with no side effects. Something like its an auxiliary power? Sure enough worked for me.

ANYWAYS, I'm pretty sure when I pulled the fuse for the GEM I couldn't turn the engine over...
Hopefully you can prove my memory incorrect on that. But. I had drain associated with two circuits. The subwoofers and the GEM. Pulling one of those fuses did not allow me to start the car. Seeing how the subwoofer fuse is still sitting in my console...

Its very possible the wiring in my car could be jacked up though as it has a Viper alarm which I'm sure was installed by a "certified technician".