5 replies to this topic

[mini_newboy]

Hey all,

Got a red light on my dash that won't go out when the engine is running, think it could be the no charge/ignition warning light. There is a brown/yellow wire the goes from the light to the alternator so guessing my alternator is faulty. To check it, do I just put my meter on a earth then connect it to the brown/yellow wire? What reading should I be getting off it?

Chris

[starletman]

Hey all,

Got a red light on my dash that won't go out when the engine is running, think it could be the no charge/ignition warning light. There is a brown/yellow wire the goes from the light to the alternator so guessing my alternator is faulty. To check it, do I just put my meter on a earth then connect it to the brown/yellow wire? What reading should I be getting off it?

Chris

Dont know about meters but a quick way to check it is to disconnect the battery while its running,if it cuts out the alternator is not putting out a charge.

[tommy13]

There are rare occasions when the ignition warning stays lit and the alternator is charging, but the light usually indicates a fault with the alternator.
To check, connect a voltmeter to the battery and with the engine running at a fast idle, say around 1500 RMP the reading should be between 13.6 and 14.4 Volts. If it hovers around the 11 volt mark of less there is no charge going into the battery.

[Bob_R]

Hey all,

Got a red light on my dash that won't go out when the engine is running, think it could be the no charge/ignition warning light. There is a brown/yellow wire the goes from the light to the alternator so guessing my alternator is faulty. To check it, do I just put my meter on a earth then connect it to the brown/yellow wire? What reading should I be getting off it?

Chris

Hi, it is worth carrying out a check at the end of the brown/yellow cable. It should be the same as your battery voltage. Also when you disconnect it from the alternator the light should go out. Basically the power through that brown and yellow line enrgisers your alternator to start the charge cycle. If voltages are right at this cable end, and the fan belt is tight, then your alternator prob does have a fault, and to be honest most cost effective solution is a straight exchange, unless you are able to de solder dioode pack and test rotor /stator etc.
On the other hand if the altenator is charging it may be that there is a ground fault on the brown/yellow and this is why the red light is glowing.
Let us know if you want some more guides to carry out a full set of tests with alternator in situ.

[mini_newboy]

Cheers Bob,

There is a few things to do & hopefully with what you have said, I can solve this issue. Will try disconnecting the wire first. It is one of the last electrical issue I have left.

[bmcecosse]

NEVER EVER disconnect the battery when the engine is running - no better way to fry the alternator......... My alternator runs fine without the small wire connected - it's really only there to operate the no-charge warning light - I know because the wire snapped on mine - and I have an ammeter - and it would balance whatever load I applied - and didn't overcharge the battery. To test - as above - meter on the battery and should be 13.8/14.2 volts at decent engine revs - then, switch on headlights + heater + heated rear screen, now what does it show ? Should still be ~ 13.8 volts - still at decent revs of course - not just idling.