Would you expect the fusible link from the alternator (which connects to the positive stud on the starter relay on the passenger side fender) to have continuity with the chassis when the negative battery cables are disconnected. I have a short somewhere that is killing my batteries while the truck is off. Any good troubleshooting info would be really helpful. I think I'm on the right track but I think the alternator may meter out that way under normal conditions.


Jason.

 

You are useing the meter in the ohms position and I would say
that is correct as the positve diodes pass thru to ground. To see if
you have shorted negitive diodes which will drain the battery go to the
volt scale and with the meter in series between the cable and the post
make sure everything is off the radio fuse pull as well as the ecm
if you still show a drain the diodes are bad. The same test can be done with
a test light.

 

The testlight is the best way, since the voltmeter is too sensitive and will give false readings if you put it in series with the cable. Hook everything back up, and do the test below. If the light lights up, then pull the alternator cable off, and if the light goes out, then you need a new alternator. If that's not it, you can start pulling fuses till the light goes out. Be careful and have the door shut or the dome light will cause a false test result too.

 

I did that exact test this morning and found the alternator to be bad. Still have a short somewhere inside the cab that I need to pull fuses and hopefully find a bad component and not have to pull the dash to trace wires around. Thanks for the info and I agree the test light is the best way to troubleshoot a vehicle system.


Jason.

 

For certain things it works better. For others, a voltmeter works better, and somethings require a good quality digital voltmeter only. It all depends on what you are doing.

 

I finished putting everything back together after troubleshooting my short problems, which are now fixed, and the battery light is on. The alternator and voltage regulator are new and the batteries measure 12.3 volts when the truck is off and when it's running they measure 14.6 volts. This seems pretty good to me so why is the battery light on. Any ideas?

Jason.

 

I am not sure what year you have, but I think you should have a red/green wire going to the "I" terminal of the regulator correct? If so, make sure this wire is not rubbing or touching any metal anywhere. This is the wire that goes through the firewall and to the dash light.