Battery light stays on

[G M Fude]

I disconnected the battery while working on my NB8B. After reconnecting it (and having the alarm go off -- hmmm, wasn't expecting that), there are two faults.

One of course is that the radio doesn't work and the previous owner never recorded the code. Sigh... none of the methods of unlocking I found on the 'Net work for me.

The other problem is that the battery light in the instrument cluster stays on constantly -- very annoying, it's surprisingly bright. Is that to do with the radio now continuously flashing \"Err\" at me? Or maybe something more insidious. Car runs and drives normally otherwise. Any ideas for making the battery warning light go away?

[Wuey]

Unless you use a key to turn off the siren prior to disconnecting the battery, most alarms go off when the battery is reconnected.

That battery light sounds alarming. Do you have a multimeter to measure the voltage across the battery terminals while you get someone else to rev the motor? If there is no change in voltage, the charging system is faulty, and you wouldn't be able to drive far, like >50km during the day before the battery is completely drained.

[G M Fude]

Yeah, that's my concern. The work I did simply involved unplugging the airflow meter for half an hour -- probably not really necessary to disconnect the battery, but I was just following instructions, and didn't expect that disconnecting the battery would fritz anything in the alternator. I'll borrow a multimeter from work and try what you suggest.

Looks like a trip to a Mazda Service Centre anyway, as I need to get the radio fixed. I seldom use it but the flashing \"Err\" is annoying and the clock was handy.

I'll definitely put it on the battery charger before driving it to Mazda, the nearest Service Centre to where I work is 45km away!

[marcusus]

I'm fairly sure someone on here knows how to bypass the security lockout. If that's all your going to the Mazda Service Centre for, I'd say wait it out a little bit for someone to give you the info, rather than being charged through the nose for it.

[G M Fude]

You're right Marcus, frustrated by the flashing 'Err' I did a search here and was surprised the radio unlock hasn't come up before for an NB. Not that I could find anyway.

Searching the entire Web, the three procedures that are on miata.net are for NA series MX-5s, and don't make any sense when I'm confronted with the particular buttons on the stocker 2002 audio unit -- I did give them a shot though. I'm a bit reluctant to post a specific query here, as for such a question I'll probably get the usual crop of forumites who'll not read my query fully and post back \"Use the Search function\" and \"This question is asked about twice a week\" and \"Not another thread on this subject.\"

For the record, I sorted the Battery warning light problem. It just didn't make sense. There was no way disconnecting and reconnecting a battery could fry something to give that problem; car electrical systems are pretty robust nowadays. So I went through what I did after disconnecting the negative terminal, which was basically unplug the airflow meter. Hmmm, what else is connected to that part of the loom? Well, only the temperature sensor, which I didn't touch. Check it anyway. Nope, still plugged in. Wait a minute... the plug had come lose! It looked like the loom was still connected to the sensor, but the plug was actually just hanging there. Push it home firmly, start car, et voila, no red light. Of course it wouldn't show up on a road test, the car will probably run okay with no temperature sensor, it just won't be particularly efficient.

Wuey, thanks for your reply too, I do so little work on cars now I didn't even know that alarms go off when the battery is reconnected!

Car is due for service in about 2,000 km; perhaps I could just put some electrical tape over the flashing radio display until then. Interesting that having one of the engine sensors unplugged should make the battery light come on. These cars are clever...