my alternator is not charging the battery (i've checked the voltage, no increase when car running, voltage drops when turn on lights, heating etc)

 

the battery light does not light up when you turn the key to the ign position

 

i know that the alternator will not work unless the battery light is ok so i have checked both the bulb, lampholder and tracks on the speedo and all works fine.

 

i've checked thatthe 2 pin plug is corectly pluged in to thge alternator, the belt is tight and the fat wire is bolted on firmly

 

i,ve checked the 10A engine fuse in the engine bay fuse box (although i think that gives the battery light on when it shouldnt be fault)

 

i'm asuming that the circuit runs from ign to the alternator 2 pin plug and back out to the battery lamp where it grounds on the speedo pcb??

are there any other fuses or plugs involved?

would a blown alternator stop the battery light coming on - i'm guessing a blown exciter diode might ?

 

is there anything else to check before i yank out the alternator and stick a new one in

well. i've looked at the speedo again, it apears i was slightly wrong, the speedo takes a 12v feed through the lamp and off to the alternator.

 

so why does it arrive at the alternator on a 2 pin plug? where does it go on the way?

the speedo takes a 12v feed through the lamp and off to the alternator.

Correct

so why does it arrive at the alternator on a 2 pin plug?

As opposed to what?

where does it go on the way?

Nowhere - direct route

As opposed to what?

 

well when it leaves the speedo it is 12v on one pin and when it arrives at the alternator it is 2 wires in a 2 pin plug, was asuming the other wire was ground, but wasn't sure as the alternator has a big fat ground connection

Just checked the manual and there should be a big earth, a big battery feed (consisting of two wires) and the two pin plug. One of these goes to the bulb and the other goes directly to the battery via the same fusible link as the big positive cable. This second wire is a remote voltage sensing circuit which is used to overcome cable losses.

Did you solve this Ian, as lisaf got the same problem ?

Did you solve this Ian, as lisaf got the same problem ?

 

yes, turned out to be the alternator, slapped a second hand one in and all has been good since :)