sheeRXhilir8tion

Just acquired another '8 -- '04, manual, 90k mi. It has an electrical problem and won't start...or do anything. No lights, nothing.

The battery voltage can be read at the starter but there is no continuity between the negative battery terminal and the negative terminal on the fuse box. Batt. + and fuse box + do have continuity.

The car had a Bennet Built D585 coil kit installed at some point and one of the stock leads (3 pin) was left sticking out far enough to get rubbed by a belt. 2 of the wires are now exposed and when I spotted this they were, in fact, crossing each other with metal to metal contact. I don't think either one was in contact with the engine or chassis, but that's not to say that they hadn't been at an earlier time, if that matters at all....

I have checked all fuses, including the large main one up front (don't think that would influence - batt. terminal to - fuse box continuity anyway). Surprisingly, none appear to be blown.

I have a bleakly optimistic hope that I'll get lucky and it'll turn out to be a relay...haven't tested them yet. However, my gut says it's probably a blown PCM... and possibly other modules as well.

I looked, just in case there was somehow a dedicated fuse just for the upgraded coil kit but, unlike the IGN-1A setup which draws it's own current, there isn't one.

I'm wondering what else I should do to either rule out or confirm PCM failure, before installing a replacement and beginning the plethora of follow-up procedures that will entail...

Any suggestions?

Thanks

Loki

iTrader: (1)

Kinda depends on which 2 wires touched. However I wouldn't go replacing the ECU just yet, it doesn't control the lights or other stuff so if nothing works at all, your problem is probably upstream from the ECU. How's the main 120A fuse? That one's not easy to check (also not easy to blow, but a different story).

[edit after rereading]

If there's no continuity negative to negative that's... weird, but easily traceable? The battery ground strap might be loose or corroded where it attaches to the body. Or, you know, dirty terminal
If nothing jumps out, jiggle the wires and harnesses to see if you get momentary light flickers, that might help find approximately where a break might be.

sheeRXhilir8tion

Thanks, that's encouraging.

I checked the 120A fuse but didn't pull it. Looks fine to me. (See photo)

I'll try doing some jiggling next. Terminals were clean...although I must admit my observations of the car's behavior were made while connected to a nearly dead battery (which was connected to a running Audi Q7 TDI). I have used it many times to jump RX-8s with dead batteries, but I gather, from what I've read, that sometimes a battery can be bad enough to not let anything flow thru it. (You'd think a light would at least come on dimly, or a chime or click.) This car has been sitting for about 5 months. I'd better exhaust that possibility before I even consider anything else!

Will update once I know more. (The car is not at my current location.)

Thanks again

Update:
Put fresh battery in, lights came on, engine cranked and started. Lucky AGAIN!
(Does not explain continuity issue. Going to take a deeper look at that...I was not imagining it...very weird ineed.)