Toyota Echo, 2002, standard shift, with around 180,000 miles: for about a month the battery light has been flickering on randomly. More and more often the airbag light comes on before or after the battery light, but lasts longer--up to 10 seconds or so. Now the headlights and dashboard lights go brighter for seconds at a time at random times, and once the heater fan revved up without being asked. Originally this only happened after about 20 min. of hwy. driving, but now it also happens sooner and later, but never while viewed by the mechanic...who says, of course, he can't test for it if the symptoms don't show. Help!! Thanks- Diana
Tried to correlate symptoms with driving pattern, battery load, etc. Nope, it seems totally random...
Hello I would be happy to assist you with your problem.
So explain to me when and how the problem started.
About a month or more ago, the battery light started flickering, blinking a few times then staying off, usually about 20 minutes into a hwy. commute. Then it got brighter, stayed on longer; then the airbag light started coming on very bright either just before or just after the battery light blinked. Airbag light stays on longer. about 2 wks ago, the heater fan revved up for about three seconds, and the headlights went bright for a few seconds. The dashboard light is going bright occassionally now. All the symptoms are now more frequent and last longer; only once did they occur when the car was parked.
The battery light will only come on when the voltage drops below a certain level or is not charging.
The alternator acts like a power generator for your car, it recharges the battery also.
Inside of the alternator is something called a "Voltage Regulator"
When these go bad your voltage can spike , drop, basically do all kinds of odd things to the electrical system.
My suggestion would be to have the alternator tested by a professional, because it seems like you have a failing one.
A mechanic tested the battery and the alternator -- replaced a year ago (not when symptoms were occurring). He says he can't do anything unless he can test it when the symptoms are occurring, which is impossible at this point.
Alright , do you know if he used a new or used alternator?
An online chat on what seemed similar problems , mentioned "fuse" and "relay." Does that make sense to you?
That is not true, you can test a voltage regulator
He got a rebuilt one from a source that he feels is reliable.
Yes but if you had a bad fuse nothing would work, not a flicker
Think of when you "pop a fuse" in your home,,
How about a "relay"?
There are no relays associated with the alternator,
When you test a voltage regulator, would "weakening" show up?
Relays are used for engaging or disengaging something, like headlight relays, or a/c compressor relay
So a malfunctioning relay wouldn't be able to send a surge of power to particular destinations?
It can, but would not effect the entire electrical system, especially not cause a flickering battery light.
You need to insist having the electrical circuit checked, the voltage regulator, either by your mechanic or a different shop to get a second opinion
So your bet is that the voltage regulator is bad and that he should be able to affirm that by testing, even if the symptoms are not present?
Yes, mind you this is my reccomendation based on what you are describing, Make sure he also checks all of the ground wires under the hood, this can also cause a flickering or odd problem with the electrical system, along with corroded wire to the battery and or fuse box.
The "even if the symptoms are not present" is because he did check the electirical system & the battery.
Something is causing spikes and drops in voltage in the vehicle. It is either bad grounds, corroded wires or a coltage regulator.
These are all things that would cause fluctuations in the circuit
Last thought... is it possible that there is something wrong "the computer" ???
The headlights getting brighter leads me to believe that isnt the case
Great! Thank you very much . diana
Since the computer has no direct input to the engine
Okay, be sure to accept and feedback is greatly appreciated
Feel free request me anytime, I work on all makes an models.
ASE Certified in Engine Repair, Performance, Brakes, A/C and Suspension.