Instrument panel

[helimd]

Hello to all. I hope somebody can enlighten me on what is going on with my 2004 Yukon Denali XL. Got up to a subfreezing morning yesterday. The Yukon was a bit weak on the start, but nothing I haven't seen before on a cold day. I have about a 10 minute drive to work and after a minute or so, I noticed that the gauges had not come alive. Panel lights worked, signals worked, radio, etc.

By the time I got to work, I realized that the battery was dying. Radio shut down, door locks wouldn't work, interior lights getting dimmer by the minute. Managed to make it to work, resigning myself to having to buy a new battery. After work I took the company truck and picked up a new battery. After installation, no change in the panel lights. This is where it gets complicated.

I located one of the 40 amp square fuses had popped and installed a new one (luckily had one in my emergency kit). Everything returns to normal. Good news until this morning when the same thing happened with the panel, but without the blown fuse. Knowing I had a brand new battery onboard, I drove to work without incident. Any ideas?

 

[01ssreda4]

Gauges are dead?

 

[03YukonNH]

Sounds like the alternator to me.

 

[helimd]

I should have been a bit more definitive about the state of the panel. The panel lights all work. The interior lights work, as well. What I mean by dead is the individual indicators, whether they be the actual needles or the warning lights, are all stuck in the off position. It's almost as if no power is being supplied to the panel.

As to the alternator, I know it works because once the system wakes up the charge indicator goes full scale as the battery is recharging. I'm almost thinking that there is a relay somewhere in the primary circuit that is being affected by the cold. That is purely speculation with no basis other than gut feel. Just to add to the confusion, yesterday I went back to the Yukon, ran the engine for about ten minutes to build up some heat, then shut it down. Waited a couple of minutes, started the engine, and everything worked as it should. Did the same thing today with the same result.

I'm a career aircraft mechanic so I'm comfortable working around duplex electrical systems. I just can't see what is going on with this system.

Thanks for the replies.