Flickering battery light

JULIET1704

MEMBER
2008 FORD KA
1.3L
4 CYL
2WD
MANUAL
85,000 MILES

Battery light came on a few weeks ago so changed alternator and battery as a matter of course as we have had the car about 5 years. But now battery light is flickering but not straight away just a few minutes after car has been started then keeps flickering. Checked and cleaned all battery terminals and earth cable to body, checked cables sockets made sure everything is secure, checked drive belt and bought an alternator and Battery tester all good.
Next called out an auto electrician £90 and he said it could be the instrument cluster sent it off £55 tested and nothing wrong with it.
Had a temperature light on for about a year the thermostat housing gasket leaked so replaced that but the socket that went on was damaged so replaced that but the light still stayed on so not sure if that is related, the car never overheats and radiator fan cuts in correctly.
Not sure what to do next as the electrical engineer said if there was nothing wrong with binicle it would be a case of a full diagnostics of the wiring looms could take hours and if he charged me £90 for 90 mins how long would be a days work? Oh he also said could be a diod in the new alternator?
Can you help!

1 Reply

JACOBANDNICKOLAS

MECHANIC
109,878 POSTS

Welcome to 2CarPros.

I have to be honest, the vehicle isn't offered in the US, so my technical information is extremely limited.

As far as the flickering light, I don't think it is a diode issue with the new alternator since it was doing the same thing with the old one. What I need you to do is take a volt meter or multi meter and check battery voltage when the engine is running and the light is flickering.

With the engine off, battery voltage should be near 12v. With the engine running, it should be near 14v. I'm interested in knowing if you get close to 14v with the engine on and if there is any variation when the light is flickering. I realize you have a tester, but I need to know the voltage being produced and if it is consistent. Also, because of my limited technical information, if you know can you tell me if the alternator has a built in regulator or if the power-train control module regulates it.

Also, let me know if the light only flickers when the engine is at idle. Does it stop when the engine rpm's increase?

Here are a few links that may help. Let me know.

https://www.2carpros.com/articles/how-to-check-a-car-alternator

https://www.2carpros.com/articles/how-to-use-a-voltmeter

https://www.2carpros.com/articles/how-to-check-wiring

Let me know the results.

Joe