Hi everyone,

I have just bought my first Chevy a 1999 UK spec 4.3 four door LT. Only had it a couple of days and about 200miles when the charge light came on. I have done some very basic testing as there is not much to test on the two wire alternator. Basically main B cable is good, ground is good but I don't know what the small red wire on the L terminal should be showing. Is it a PWM signal or is it direct to the charge light/resistor? The symtoms are basically the alternator appears to be giving no charge at all.

Thanks for any help..

 

In the states, our auto parts stores will have test benches on which an alternator that is brought in can be tested. Could you do that there?

 

On an alternator of that year I believe that the "L" terminal is an output to the PCM to turn on the dashboard charging light. The alternator and its internal regulator are a self contained voltage system. What is the system voltage when the truck is running?

George

 

Hi,

Thanks for your replies. Alternator testing is not common here. Most places just sell/fit new parts and hope the problem is fixed.

I was happy with the battery cable connection and also the ground connection. Just not sure what I should be seeing on the L wire. The running voltage was a little less than engine off battery voltage so the alternator seemed to be doing nothing.

Anyway I took a chance and ordered a used item from ebay and this is working fine so I'm happy with that.

Steve