Electrical Question GMC 2500HD Sierra (Page 1/1) Brimmy DEC 22, 06:32 PM Okay, Lets hear your ideas... My GMC is '03, with the Duramax. My Electrical issue is as follows; First start up in the morning; or after truck sits 2-3 hours or longer, Truck fires up fine; blower running, radio on, lights on, however; heres the interesting factor. All the gauges on the cluster & odometer are not powered on yet; but after truck is running a few minutes; it is almost as if someone flipped the switch to "on" (Like a voltage boost.) The gauges then power on; the blower actually speeds up & the lights brighten up a bit as if the Diodes in the alternator decided to let some power back into the system. Does this sound like the regulator in the alternator is going bad ?? Thats what I am thinking; wanted to see what others might think? Thanks. tesmith66 DEC 22, 09:08 PM You have one alt or two? My Powerstroke has two, and the lights will brighten and the blower motor speeds up when the second one kicks in. The volts jump from 11. 8 to 13.4 when that happens. Brimmy DEC 22, 10:30 PM quote Originally posted by tesmith66: You have one alt or two? My Powerstroke has two, and the lights will brighten and the blower motor speeds up when the second one kicks in. The volts jump from 11. 8 to 13.4 when that happens. Just one alt. I am going to get the volt meter on it & see what it is doing. DKcustoms DEC 23, 08:45 AM I would check the fuse for your instrument cluster, you could have some corrosion develop in there that could prevent a good connection until things warm up. Also, check the ignition switch, there could be a less-than-stellar connection that, like with the fuses, may have some corrosion develop and lead to a bad connection.