saintz

My COMAND is refusing to power on. My CD changer has no power (eject button is not lit, won't eject). WTF?

I installed a CD changer. I don't have an extra fiber connector in the trunk (I think it's because I have nav and phone installed, which take all the stock fibers). At first I disconnected the fiber connection for the phone and used it for the CD changer. This worked. Then, a month later, I attached a D2B fiber extension/splice. I wired it into the CD changer and tested everything out. It worked.

Now the problems. I sealed up the trunk, reinstalling the panels. I installed the CD changer bracket. I turn the car on, and nothing. No COMAND power, no CD changer power, steering wheel display says "Audio" with a blank line under it.

I tried pulling the fuses 5, 15, and 16 under the rear seat. I tried removing the CD changer and rewiring it like it originally was. Nothing works.

Any ideas? Please help.

saintz

I cut battery power for 30 seconds to see if the system needs a reboot. Still the COMAND is dead (and CD changer won't eject, has no power).

I pulled each and every fuse under the rear seat and in the hood. All appear good.

The entire audio system appears to not only be dead, but have no power. The COMAND won't even power up it's cooling fan, let alone turn on. The CD changer won't light the eject button and won't eject.

It's like it's totally dead, but doesn't appear to be a fuse issue. What else could it be?

saintz

Ok, I hooked up Carsoft. I ran a digital test on the D2B system, and it came back with error B1241. I cleared the D2B errors in Carsoft, reran the test, and the error was back.

I tried to reprogram the D2B bus arrangement in Carsoft (radio, audio system, telephone, navigation) but it threw an error.

saintz

It appears my cigarette lighter is also dead. I need to confirm. Now I'm thinking it may be a fuse problem.

Edit: Nope, cig lighter works.

Semikolon

Did you check the main fuses? and are you sure the fuses are good? they may look good, but still be broken. try replace the fuses related to audio.

saintz

Thanks Semi, I just replaced nearly all the 15 amp fuses in the whole car with new ones. I'm going to start replacing all the others, too. I'm starting to feel it may not be a fuse issue.

P.S. - I was wrong, the cig lighter does work, so that doesn't help narrow it down.

saintz

I have replaced most of the fuses in the car now. No dice. Going to try a long battery disconnect.

saintz

So it looks like the error code B1241 is a refrigerant low (air conditioner) code. I don't know why the D2B/stereo would be throwing that code when I run a diagnostic, or if that's related.

Semikolon

Remove your comand unit and measure voltage in connector block A (power block). You should have constant voltage between pin 4 and 8, and switched voltage (ignition) between pin 7 and 8.

The cd-changer draws its power from connector block C1 (8pin)


To remove the unit:

-Pull out the climate control (using radio tools)
-Remove the wood trim around the gear. Just pull it straight up and turn it 90 degrees to the side, then it's out of the way. No need to disconnect wires.
-Unscrew two screws on ashtray
-Remove ashtray, pull up and out
-Unscrew the two screws holding the wood center wood trim in place. They are located behind the ashtray, under the wood trim. you may need a flashlight or something to see them.
-Pull out the wood trim
-Remove switches to get the trim completely out of the way
-Unscrew one screw on each side of the comand unit to get it loose
-Pull out and disconnect wires

saintz

Semi, thanks for the info. I haven't yet pulled the COMAND, but I tested the CD changer input (easier to get to).

It should be:
Blue: Switched voltage, tied to ignition
Black/Red: 12V constant
Brown: Ground

Instead, I'm getting:
Blue: 15V constant (no change with ignition)
Black/Red: 4V constant
Brown: Ground

This is very weird. First, it's not providing an ignition switch (wake up signal) to the CD changer anymore. Second, it's only providing 4V of actual power. I think this is why the CD changer won't power up (i.e. won't eject the cartridge, which it should do even with ignition off).

I have also pulled every single fuse in the whole car and tested it with a fuse tester. All are good. Now that I see the CD changer power output, I'm wondering if it's an issue with a relay. It's getting power, just not enough (4V vs. 12V).

Next, I'm trying what you suggest Semi. Based on what you're saying, is the CD changer fed by the COMAND? Meaning if COMAND goes nuts, can it cut power to the CD changer?

Any ideas? I'll post back when I have COMAND power cable outputs.

saintz

Pulled the COMAND. There is a 10 AMP fuse in the back of the COMAND. It appears that the bracket for the CD changer was somehow causing a short when it touched the chassis of the car. Once I removed the CD changer bracket and changed the fuse, the COMAND is working again.

Thanks for the help Semi.

Semikolon

good thing everything is working again!