What would cause the red Battery and Brake lights to flash at times

[m.w75]

Hello, I'm having a little problem with my 1990 corolla sedan, automatic. thought I'd post here and try to get some suggestions or help. I've noticed that every now and then that the red battery and brake light under the speedometer flash or stay steadily lit for about 10 seconds, then stop. The first time this happened, I checked that the emergency brake wasn't engaged, even the slightest, and cleaned the battery terminals. This was about a month ago. And I just noticed that it happened again today. Being that the lights only flash for a few seconds, I'm not sure how often it's doing it. I was at a stop light this last time and happened to look down and they were actually steady lit at first, then went to flickering, then stopped and didn't do so for rest of the ride home. Oh also when it first happened, I googled it and it said something possibly with the alternator and to do a test with a screwdriver to see if the alternator felt magnetic, which it did. So I don't know how relevant that was. Any insights would be appreciated and thanks in advance!

[90 GP]

Alternator is most likely culprit. Either the voltage regulator ,worn brushes or voltage regulator inside it are worn out. Get free charge system check at autozone/advance to confirm it.

[REN69]

yup, sounds like it's starting to go and it's giving you early warnings, once those two lights stay on it's only a matter of days before it stops charging completely.

I just went through this with the Supra and ended up swapping over to a 70amp alternator from a 7M.

[RogueMoog]

Those lights have been coming on and going out constantly in my wagon since I replaced the clipped fuse I found under the hood (for the charging system, 7.5 amp fuse I think). I had the charging system checked out at Advance Auto a few weeks ago, and their tests said it was fine. I'm starting to wonder if a bad engine ground wire will cause the same thing to happen. Sometimes I will hear random clicking & popping in my speakers when I listen to music when the car is off (for short amounts of time).

You can see the Advance Auto printed report for my charging system in this topic:

90 Corolla alternator repair?

[Flashmn]

Can be grounding problem in the dash too. Check it for corrosion.

[Sturdavj]

If you have access to a multi-meter, check the impedance/resistance level in the brake circuit. If your brake lights are flashing there is a good chance there is a momentary increase in resistance in the system/circuit.

Identify the complete brake circuit end-to-end, pick a location midway through the circuit, separate circuit in two halves, first test one half then the second half, separate the halves into halves (in to 1/4’s) repeat the process until you locate bad (1) wire; (2) bad connector; (3) a bad crimp on a connector;(4) a loose ground (6) 12+ feed from an adjacent wire/circuit.

Good luck

[RogueMoog]

For my problem, what I meant by the two dash lights coming on and going out is that they will come on and stay on for a while. Sometimes for an entire drive (10-15 minutes). They will randomly turn off, only to come back on after a while. I'm not looking forward to chasing that gremlin...

[Sturdavj]

Yes, a hard fail is much easier to TS

good luck

[Donald]

That is warning I got before the alternator in my Camry wagon died on I-95 on a Holiday weekend.
I say get a junk yard alternator.

If the problem persists, then you start chasing grounds.

[datsa]

I have this same problem. And I am on my 3rd alternator; the first one lasted 28 years, the second only six months, the current one four years. I rechecked all the engine grounds and there is a damaged ground between the block and the right fender. I still need to check the dash grounds.

I am wondering if it is being caused by something other than the grounds and a bad alternator.

I notice that it goes away after a while, and that sometimes when I clean oil off of the harness plug that goes from the battery to the distributor, the lights go away. Perhaps that is a coincidence.

My current alternator checks out fine with a multimeter. For my next alternator, I am going to get a better one from a local alternator company.