Bad Diodes

[camlex]

Hello,

No battery charging light on dash board and bad alternator. Is it possible?

Orailly says "Bad diodes"

Thanks,

[George_Jetson]

This is the schematic for your car. What type of test did they perform before telling you the diodes are bad? While this is possible, it is not likely. First you would want to check the alternator warning light, this is much more than just a indicator bulb. The 12v signal that comes thru the bulb supplies the feedback to the regulator. If the bulb burns out, the alternator will not generate any current. There are also several other fuses that you should check before condeming the alternator. But there is a very high possibility that the bulb is burned out, and that is the only problem.

[camlex]

When i put key in ignition, Battery light shows on dash board. I will let my mechanic check.

Orailly attached scanner on battery while car is on and i saw on scanner,"bad diodes" message.

Thanks,

[George_Jetson]

Hello,

No battery charging light on dash board and bad alternator. Is it possible?

Orailly says "Bad diodes"

Thanks,

Ok, When I saw the no battery light, That made me concerned. I would recomend checking the fuses associated with the alternator, and then replacing it.

[camlex]

New Battery and everything is back to normal

Thank you.

[George_Jetson]

The battery, I'm surprised, especially that the auto part store would give a error for diodes. That is really strange.

[camlex]

My mechanic mentioned that he checked the alternator for A/C power. No A/C was detected. He suggested to change the battery.

After I replaced the battery (from o'reilly), we checked the alternator again. Now, "Good diodes".

I told him about yesterday. He agreed and said that a bad battery can create that message.

I bought an 84 months with 36 months free replacement battery.

Again, thank you for your help. You are a good help for all of us.

[George_Jetson]

I use my DVM to check for ac,(set it to read ac voltage), you should see very little ac on a good system. You will allways see a little bit, because auto alternators general 3 phase ac current, which is rectified by a full wave diode pack (6 diodes), so there will be a little ripple. Interesting that the O'reilly tester thought there was a bad diode. It might possibly be that the battery was old enought so that it's impedance was too high.

How old was your battery? Interesting I will look into that a little more. And you are welcome, glad to help people save a couple dollars.

[camlex]

Interstate, Installed on Jan. 2006