SCombs

Today my wife was driving our 2012 Express 3500 6.0L and it was running fine when backing it out of the driveway. Then the entire instrument panel went dead, no HVAC blower motor, no turn signals, no daytime running lamps, no radio, nothing electrically supplied seemed to be working. The engine stayed running and the brakes worked, and she drove it to her destination and kept the van running. Then when she came back home and turned the van off the check engine light came on and stayed on and was dim even after the key was removed from the ignition. She tried turning the van back on and nothing, but the check engine light grew brighter when turning the ignition on and then turned the ignition off and the check engine light grew dimmer again. Also, it appeared the brightness of the check engine light was fluctuating without the ignition on. Another interesting point is that when I open the hood the light on the hood will come on but is dim compared to the brightness when the van is operating correctly.

Anyway, I plugged in our DTC reader before I turned the ignition on and the lights on the DTC reader display were fluctuating brighter, dimmer, brighter, dimmer, etc. But the DTC reader never fully powered on. Then when I turned the ignition on the DTC reader went dead as if no power.

This has occurred in the past about 4-5 times. They way I've symptom solved it was disconnecting the battery and reconnecting it multiple times until I would hear chimes going off such as when you put your key in the ignition and turn it to the run position. Then the van would operate normally until the next time. At one point when I had some time to do a preliminary investigation, I have checked the following relays: 15 Micro G8V for RUN/CRNK and 39 Micro G8V CRNK thinking that this might be a relay issue. But the relays clicked when pulling them in and out of the socket. Some other information is that I did put in a new stereo system 3 years ago. I also keep the van on a trickle charger since then or the battery goes really low over 3-5 day and shorter in colder weather since the stereo install...I am not sure that this has anything to do with the van not starting though.

Any insight would be appreciated.

Rednucleus

Welcome to Chevy!
How old is your battery; have you measured voltage or had battery tested?

SCombs

Thanks for the reply Rednucleus. The battery is a DieHard Gold and approximately 2 years and 10 months old. I just read the voltage at the terminals and the two different readings were 12.83 volts for each reading.

mountainmanjoe

Batteries should not go flat in 5 days. You should have dealt with that problem immediately. Not only will this prematurely kill your battery, but the alternator will work itself to death trying to keep the battery alive.
If I were you, I would go get them both load tested. Then I would remove any aftermarket electrical accessories , including the stereo, and see the if the drain problem goes away.

SCombs

Thanks mountainmanjoe for your reply and appreciate the advice to act on. The issue I have right now is that I cannot get the van started and I have a fully charged battery. When I connect the charged battery to the vehicle, the check engine light is on and the key is not even in the ignition yet. And when I put the key in the ignition and try to start it, there is nothing except that the check engine light actually get brighter. The dome lights don't come on. The only item that appears to be working is just the underhood light when I open and shut the hood.

As mentioned before, the only way I have solved the system is that I connect/disconnect/connect....until I hear like the chimes you hear when you leave your keys in the vehicle. I was thinking that there might be a relay that is not functioning properly (like it was stuck on). At that point the battery is charged and the alternator is not running. So something is preventing the engine from turning over.

I need help with getting the Express started so that those items can be checked.

mountainmanjoe

The battery might look charged, but it's degraded from the constant draining. get it tested.
Or you have a short. Like I said, unplug anything that's suspect like the aftermarket stereo.

Otherwise, since everything is dim then you might have a janky connection. The wiring, the main fuse, etc ....
are you battery posts and cable terminals all clean and tight?