ICE Gurus! Or anyone with the most basic electrical knowledge

Theoretically speaking, if someone bought a scruffy looking amp off eBay, was assured it worked fine, then followed the instructions here to wire it up, after all that got annoyed that the amp wouldn't power on...and then 6 hours later realised that earlier on he'd actually connected up the amp's power lead to the negative terminal of the battery instead of the positive...

...what would be the likely outcome? Blown amp? Nothing whatsoever?

Theoretically

Should be fine - have you tried the amp when it's connected to the positive terminal?

Yeah - was just messing about on here when I suddenly realised it was connected to negative, so got out of bed and went down to sort it. Connected to positive and still nothing. REM is connected properly, ground is connected to the frame the seat is mounted on (though this isn't bare metal). Still no flashing lights on the amp.

Might buy a multimeter from maplins tomorrow

That could be the culprit then.

'Theoretically' if the Amp has a fuse like an immobiliser to stop it frying the Amp if it got any serious power surges, then you may want to check that too or try swapping it with one of the same rating just so as to eliminate that out of the equation and crazy as it sounds double check and triple check all your earth and negative connections from your ICE unit to your amp are secure and sound. Use an electrical tester too if you have one (if not they cost pennies these days, just go grab one or ask a mate) to check the wiring to see if power is going to the unit.

Hope that helps you out a little

Cheers for the advice guys

The fuses are OK, they're 2 x 30A (at least I think they're 30A. The green car ones anyway). The fuseon the power cable near the car battery is also still intact. The car seat frame that the ground is attached to is definitely painted in some way. It's like a glossy dark grey. To be honest I didn't think that would be any big deal that it wasn't bare metal, so tomorrow I'll have to find somewhere to ground it.

Will also get a voltage tester, I just checked and they're only a fiver

yeh you ground will be the problem. If you dont want to move it elsewhere, you could sand-down to the metal to get a good contact. Personally id then be tempted to give it a little bit of paint once its connected to prevent any moisture that may be present from corroding the metal/contact.

cross the REM terminal with the main red one on the amp first so you can be sure its not just the REM wire,., the REM just needs 12v + and it'll turn the amp on. if that works then you need to sort it behind the stereo.,

OK an update on this:

Got the amp working! All I needed to do was make sure that the head unit was switched on AND set to a function i.e. not in "sleep" mode with just the clock showing

That grounding point I used, the car seat frame seems to be fine so I'll leave that.

Anyway it's good to know all the wiring was done OK in the first place. I bought a voltmeter and did some measurements a few mins ago. The power lead going into the amp was 12V as you'd expect. The remote lead going into the amp was about 10-11V though - I thought I'd read that this should just be a tiny voltage?

One other thing that surprised me: when I switched the stereo on, there was music coming from the CD! I thought this was weird because I'd disconnected the in-door speakers from the factory-fitted wiring and wired them through the car ready to be attached sometime to the crossovers and onto the amp. Turns out I only did the midwoofers and forgot to disconnect the tweeters and wire them through the car!!

Hehe learning all the time - thanks everyone

Well done, glad to see you got it working
Next time if you have to do it again I am sure you won't have a problem.

the REM only "needs" 5v but its ok if it has 12 or less.,
as for it not turning off. the fiat witing means that the stereo doesnt turn off when you remove the keys so your gonna have to run a cable to the ignition harness. use the orange wire at the harness and run it to the red positive behind the stereo,(not the yellow constant). make sure to dissconect the red from what its already attached to and then just attach it to the new wire.,

it should work properly now.,

I would defanately move that earth your gonna fry ur amp and poss even worse it needs to be on bare metal attach it to a rubbed down patch near the spare wheel bay then you will still have an amp in a couple of weeks time.

I agree with volxstu attaching ground wire to bare metal is vital or it is likely you will be buying a new amp in the near future... i have had this problem before

yup, intermittant power is a great way to fry any electronics