So apparently there are differences in grounding certain electronics.

I went to install an Autometer air fuel gauge. and it said to ground it out to an ENGINE GROUND. Being retarded i grounded right to a bolt on the firewall. (like i have done with any electronic that i have wired up. (systems, amps, headunits etc.)

So after hooking everything up, i went to turn it on and it blinked on and then out. and has never came back on.
I assume i have fried the circuit board in the gauge. So its ruined.

Where should i have grounded it too?

 

Revision: Headunits i always use the factory stereo ground wire.

So would that be an example of an engine ground wire? because i know that if you want to fry out a headunit you can just touch the ground wire coming from the unit to a piece of bare metal. much like how i hooked up the A/F Gauge....right to bare metal and bolt.

Could i just splice into the headunit ground wire?

 

there should be zero difference between the engine ground and chassis ground, if there is you have a ground problem.
technically speaking yes there is always a difference, but it should only matter if you're worried about an offset of .25V or less.
I've hooked many car stereos up using a firewall grounding point, never had one blow on me.... then again I make sure the engine to chassis ground is in good shape before I do anything with a stereo. Way to many times I've found that the alternator power isn't getting to the rest of the car due to this.

IMO, with the Autometer A/F gauge, connect power/ground/signal at the ECU.

 

I have found there is a low low ohm difference between ground points on a car, generally speaking if you are in question about grounds measure them and then use a larger gauge wire between the engine block and the frame and make sure you scrap off the paint so it makes a good connection.

less then an ohm difference and your pretty good.

 

alright i did that and did a little testing. once i ran it to the correct spot it did light up. Which is a plus. I DIDNT FRY IT OUT! but still the same thing starts up and then shuts off.

So apparently it could be a bad O2 sensor reading. According to autometer, if the gauge is not getting a proper O2 reading then it will not display anything?

i am going to re-splice the wire and then test from there. hopefully its that simple. if not then its the gauge and that is why we have warranties right lol. thanks for the suggestion

 

I ground my LC1 XD16 gauge to the thermostat housing, its good enough for the ECU.