Thread: Alternator light is on?

Originally Posted by land864

Mmmm

Coming out of the Eastlink tunnel tonight , turned off headlights and then alternator light came on. I think it was that close?

Anyways , pulled over , belts all on , alternator spinning around like it should , no obvious loose wiring , no special Lucas smoke comimg out of anywhere

Got home , had dinner and then out to see what I could see.

Facts are this;

1. Battery at 12.7 volts engine off ( 12.24v engine on? )
2. Alternator putting out 12.5 volts at idle
3. With headlights on alternator putting out 12.18 V

Someone has suggested a broken wire somewhere but the question is how the heck would you find it !!

What vehicle?

Check the voltage regulator and the wires connected to it. Especially the positive source which goes to the ignition. These wires tend to perish over time with heat etc increasing the resistivity and require replacing.

I had my alternator light on the dash flicker particularly when load on the alternator varied i.e. lights on to off or a/c on to off etc.

The voltage regulator is located on the passenger side strut tower (near to shock absorber access cover)...on a 86 county anyway.

Failing that, you could be looking at a problem with the alternator itself.

Hope this helps.

Originally Posted by Gavo

What vehicle?

With prince of darkness, can only be the Isuzu or stage 1.

Edit
Whoops, just saw there's some series in there 2. Good question.

Either way,

A multimeter with a alligator clip should be able to find it using the circuit tester mode. You might also be able to rig up a buzzer or globe using a 12v battery to test a wire's integrity, use the wire you are testing to complete the circuit. No circuit, no worky...

Thanks Guys

It's the Isuzu County.

Doesn't seem to be losing any voltage.

Had 3 starts today and sitting battery voltage is still at 12.5 approx

Will check the reg wiring though , thanks.

With the alternator charging, battery should be over 12.5. I assume it has the separate regulator inside the LH guard - check this, and in particular, that the earth wire has not burnt out. If this is the case, the engine/chassis earth strap is open circuit or high resistance (it is across the LH engine mount) possibly due to oil plus loose bolts.

Another possibility I have run across is a loose (rather than broken) fan belt.

John