my roommate has a 1990 Mustang 5.0 and we can't get to the bottom of this charging issue the car has..

It has a brand new battery
We took the alternator to Canadian Tire for a test and it passed with flying colours.

When the car is running, the voltage across the battery is 11.9V and the voltage from the positive of the alt to a ground is about 11.85V. When the throttle is blipped the voltage drops about 0.1V and then picks right back up to where it was.

Reading the Haynes manual it says to check the fuseable lines for damage. Now we can't see any visible damage, but it there a way to check the current through the line without cutting it in half and putting a multimeter in series.. Also the "Load sensing wire", is there a way to check current in there without cutting it?I don't know if this is a Blue Oval special, but these wires are a part of the harness connected that is connected to the alt.

Any electrical gurus, or anybody with insight, your thoughts and opinions are more than welcome.. We've exhausted our brains, which is why I've asked Dodge guys and gals about this stupid Ford problem..

 

moe in wichita ks
check the diodes

 

pardon? What are the diodes and how do I go about checking them? I'm not a noob, just electrical stuff confuses the crap outta me..

 

ooooooh, diodes, you mean little light bulbs... i could peel back some sheathing and touch them to the wire, they'll light if theres current going through...

thanks moe

 

moe in wichita ks
diodes are inside the alternator they change ac to dc. i think the alt has to be taken apart to check them.

 

The diodes control output voltage and direction(they are not light emitting diodes).
The voltage at the battery when running should be around 12.8 to 13.4 volts.