My friends have (my old) 2002 Accent with the 1.6 DOHC that I've been puttering around with all weekend.

The door was left open a crack and the battery drained. It was brought in, didn't charge right (he said he accidentally put the cables on reverse). Tried to install it, still did not start, put it back on charger correctly, and then re-installed. It was unknown at the time, but the black cable that went from the negative post to the fuse box popped off, and then he said there was no lights in the car, but tried to start it anyway.

We tested the battery both with a voltmeter and at a parts store - its testing like a brand new battery. I've tested all the fuses in the box under the hood, and in the box by the driver's feet. I also tested continuity in the ground to the engine, ground to the body, ground to the fuse box, and the alternator to the fuse box cables. All the wires show up as less than 0.5 ohms resistance (I'm assuming since I didn't get an infinity reading that they are intact).

I then tried to just put the key in the 'on' position to see what I could get - no interior lights, no start, no accessories at all. It wouldn't even let me shift it with the key in. I've got no clue what left to try. I guess these don't really have a "main relay" but at any event I don't know how to properly test these relays anyhow.

Last year I replaced the positive cable to the starter, and the CD player was error-ing out (it kept reading that there was a CD being inserted then stopping and then turning on the radio) so I just pulled the fuse under the hood. I don't know if they would have some effect over a year after the fact, but... *shrug*

Any suggestions would be appreciated!

 

Best guess, your friend may have fried the ECU. My '08 Accent has the cables positioned toward the back of the tray and a mark on each post clamp to prevent cross connection, as does my wife's 2002 Windstar. Regardless, you're looking at $200+ for a used ECU. I would have it towed to a reputable shop and have them troubleshoot it for you to find out EXACTLY what is wrong. Based on the OP, I'd have the shop do the repair, just my opinion on this.

 

^^^ That would be my guess. Many times if you hook up the cables wrong, it kills the ECU.

 

He hooked it up wrong to the battery charger, not the car cables, but the thought had crossed my mind...

 

It still sounds as though the ECU has been fried. I've reversed the cables jumping a car before and got real lucky I didn't fry either ECU (both the cars I listed above and I was REALLY tired and frustrated that day). There is something else you can try and I did after losing my timing belt (before I knew what happened), a auto guru I know posted the following on another forum some time ago, but the general principles apply to all makes and models.

Give it a try and keep us posted