I just changed the battery cables on my truck (1989 F150 XLT 4X4) and I noticed the voltmeter is reading low. This gauge displays alternator output? Is my alternator going bad? I also have changed the turn signal\hazard switch, ignition switch, and hazard flasher. Please help...

Thanks

 

It shows the voltage between the fuse block and the dash ground. Get a handheld multimeter and check it yourself to see if the dash gauge is still accurate. The Haynes manual shows where it's wired into, and where the dash ground is.