Brake & Battery Lights On Dash

**bennoc** · 23-01-2013, 07:13 PM

Hi guys,

I hit a speed bump a little hard today in my RN85 and afterwards noticed my brake light and battery light on the dashboard were on. I had a look on the web and saw that it's likely the alternator, but I'm wondering if it's possible it could be something else, as I've tested it repeatedly with a multimeter and it's sitting around 12.8 when the engine is off, and when it's running sitting up around 14 and doesn't seem to drop. I drove the car around for about an hour this afternoon, and the multimeter still shows it's at acceptable levels so I'm not sure what's going on.

The lights go out when the car gets down to a low speed of around 20kmph but when I pick up speed they come back on, so is it possible that the battery is getting charged when sitting at lights and causing the multimeter to show acceptable readings?

It's confusing me so if anyone has seen this before and can point me in the direction for things to check it would be appreciated!

**HAVABEER** · 23-01-2013, 07:54 PM

have you checked the fuses?

also, you'll find your car will actually generate MORE volts at higher speeds, as the engine is reving faster so the alternator is spinning faster making more current then at idle. if anything i'd be checking for dodgy earth somewhere, or get someone else to stand on the pedal and make sure a bulb isn't blown or lose in your tail lights

**bennoc** · 23-01-2013, 08:09 PM

Just checked the fuses and they all appear fine. Also checked all the lights and none of the bulbs are blown.

**GT1978** · 23-01-2013, 10:22 PM

Does the voltage increase above ~14.8volts when you rev the engine up? Charge light will also come on if alternator is overchaging the battery. If your getting up near 15.5V when the revs are up your regulator might be shot. If it is best to get it fixed quick as some gauges etc don't like excessive voltages.

Glen

**bennoc** · 24-01-2013, 09:50 AM

When the engine is off, the battery sits at 12.75 and when the engine is on it's at 12.48 and doesn't change when I rev the engine. Then once the engine is turned off again the reading goes straight up to 12.56 and then slowly creeps back up until it reaches 12.75 again and sits there.

Don't think it's the voltage regulator as it's not getting anywhere near the 14 range.

Just took it for another drive around the block and the readings above didn't change after it. I've got no idea what's going on.

**bennoc** · 24-01-2013, 03:52 PM

Just took the car for a 20 minute drive and the lights never came on at all this time. It's bugging the hell out of me now.

**TERRA Operative** · 24-01-2013, 04:22 PM

Look for loose plugs and earth terminals everywhere.

Also, you should be getting around 13.5V - 14V with the car running. I had a regulator go on my Levin recently and I was barely getting any charge.

**CrUZida** · 25-01-2013, 04:38 PM

The light can be intermittent when the alternator is beginning to fail.

I've had a car where the light came on, we put a new battery in (because the car wouldn't restart), and then the light didn't come back on. Sure enough though, 2 days later it came back on. Alternator was replaced, all was good with the world.

**bennoc** · 10-02-2013, 12:10 PM

Just following up on this, the alternator finally died last night and driving home the dash lights dimmed, and then the indicators stopped working, and then the lights went out but I somehow managed to drive another 10 minutes to get it home. I took the alternator out this morning, and noticed in the pic here that there is some rubber thing that looks like it had wires running into it at some point.

Can anyone identify what that is, if it's important or was the cause of my problems, and how easy they are to source?

**CrUZida** · 10-02-2013, 12:47 PM

That just looks like the noise surpressor. Won't affect the alternator.
As long as the big plug with 3 wires is fine, and the big fat cable is bolted on, if the alternator is good it should still work.

**dumbass** · 10-02-2013, 06:45 PM

If your alt was not charging over 13 then it shat a voltage reg
Best test for the lights is
Unplug the three pin plug of the alternator
If the dash lots go out while motor is running then its def yr alt
No fking way it's going to be fuses as the lights do actually come on
Yr alternator is not working so its bringing the battery light
Which in turn is bringing on hand brake light