im after a bit of advice folks.
this truck ive bought has developed a bloody fault. .
driving along with the lights on they go dim then brighten back up, also the voltmeter drops and the fans slow down. when ticking over its showing 13.8 on the multimeter but dips to 10/11 with lights and fan on.

so is my alternator foooobarred?

i would surtunly try checking the connection to to the alternators . and the battery earth . if you get it off there a good bloke in glos that will check and repears it . normaly comes in at about 30 quide

cheers, will check that out.