I am inclined to think this is BCM related, perhaps a software glitch/corruption.

I'm under the impression that these specific lights are always fed +12v and it's the BCM the one that controls them providing, or taking away, ground directly to that circuit with no relay involved (it's only a few miniature bulbs consuming just a few milliamps), but I haven't confirmed this.

If this is caused by the BCM acting up, I don't know whether is possible to "reflash" it with "clean" software. Does anybody know if this is possible?

 

Does he remember how this began? Did this problem appear out of the blue, or after something happened to his car?

 

This might be a good experiment, but as you said, it sounds it could become very "involving"

 

What makes you think the BCM controls the lighting for the DIC switches?

 

the dic and hud switches are "piggybacked" to the instrument cluster, which could be the issue or the bcm is connected to the cluster, might be a issue. If someone knows speak up...

 

I don't remember offhand but I was looking at a schematic when I posted that. I'll look again later...

 

my 2000 just started this out of the blue about a week ago. did anybody find any thing out before i remove the bulbs. thanks shawn

 

I've been tracking down this issue for quite a while trying to find a resolution, but nothing yet... The people who have reported it never came back with an outcome...

I don't want to take my car to the dealership so they could experiment with it I know that fuse 25 in the fuse/relay panel under the passenger's feet powers those lights among other things. I decided to install a remote switch connected in series with that fuse, and hide it somewhere under the driver's seat. That way I could easily interrupt power to the DIC's backlights after I turn off the car and re-establish it before turning the car on. I already purchased what I need, but haven't had time to install it.

I know it is not a solution, just a workaround, but it will allow me to regain some normalcy

 

One thing that was not mentioned was the dimmer **** and slider.

Did you check the dimmer **** to make sure it has not been in the always on position? I know its really obvious, my apologies if you tried already.

I am dealing with the same issue now.

 

Yes, I did! It would be great if it were just that!

How did it happen to you, just now out of the blue?... Suddenly?

 

Oh well...

I was doing a gauge face plate install and messed up the wiring - think I blew something in the cluster so I just plugged a new one in. I now have your problem and additionally blowing fuses 6 and 29 either when the headlights are on or when the headlights are on and the car is driving (thinking a loose wire somewhere causing a short). I have a thread going that I neglected this past weekend, but will get back to it tomorrow night.

If I figure it out, I'll let you know.

 

Sorry to hear about your problems... If you find anything, please let me know

 

In case any of you are interested I am helping some one with the same issue on this link:

http://forums.corvetteforum.com/c5-t...post1585780347

My opinion is that it is the IPC motherboard. A friend here in town had a similar issue but only on the HVAC unit which would not dim but other lights would. Installed a spare unit and it worked fine. Not sure what the owner wants to do in the above post but you can follow it if you like. I would like to resolve this for the Forum.

 

Here is my conclusion from the link in the other Thread above in Post #34.

Here is a link to a repair shop I just called. He agreed the lights for the HUD and DIC switches ARE powered from the IPC. He said he could fix that for $120.

http://www.instrumentclusters.com/

 

Bringing this thread back up. Anyone have a cure for this, besides sending the IC out for repair.

I was just quoted $300. by these guys

After looking at the circuit boards of the dimmer & DIC, looks like all you need to do is cut the yellow or black wire on the DIC harness or the brown or white on the dimmer harness.

Those are the wires to the light bulbs. (on my 1999 FRC)

 

If you don't care about not having lights in the DIC, why cut the wires. Just remove the bulbs in the DIC.

 

My bulbs were soldiered in on the board, didn't want to ruin the board.
3 bulbs on the DIC board & 1 on the dimmer board. (99 FRC)

Cutting those wires fixed the battery draw & everything else works fine.

 

My 97 which has a HUD and gauge cluster from a newer c5 has this problem. I'm thinking about cutting the wires like mentioned and running a relay that will power them on when the park lights are on. I'll try this in the next few days and report back how it works out.

 

Good idea

BTW- still no problems with the wires cut, everything else works fine

 

Did some probing with the multimeter and found the relay isn't necessary.
Looking through various diagrams and the description of operation it seems the back-lighting for these switches was never meant to dim along with the others, which was a concern someone had brought up. I can't confirm whether that is true of a normally operating car since mine was staying on all the time. Regardless, the lights will not have that function if you use this method. Verify the functions of each wire on your car before you start cutting stuff. This worked for me, but we know our IPCs are malfunctioning or we wouldn't be having this problem. It could be possible they aren't all malfunctioning the same. Just saying, do some testing before hacking up your wiring.
Luckily there is a second 12v+ with park lights on signal that feeds the dimmer switch, so I decided to try to use it to power the other lights and forgo using a relay.

On the short harness running from the HUD controls/dimmer to the IPC I found that the white wire and brown wire are the control for the back-lighting. The white wire had a constant 12v+ while the brown wire held a constant ground, rather than one of them being switched as intended. I cut the white wire and jumped it to the green wire which is a properly functioning 12v+ with park lights. I also removed the remaining piece of white wire from the IPC side plug on the harness since this wire had constant 12v+ and I don't want it banging around shorting something out.

Moving on to the DIC controls and the harness on the other side, the back-lights are ran by the black wire which had constant 12v+ and a yellow wire as ground.
On the other side there is no alternate source of signal, so I ran a jumper from the same green wire on the first side to the black wire on the switch side which I cut in the middle of the harness. I discarded the black wire on the IPC side, just like before to eliminate the chance of a short.
My button back lights now turn on/off with the park lights, and no longer stay on draining my battery.
I'll do more functional testing over the next few weeks while driving the car (after my rear bumper gets back from the paint shop) and report any issues I find.