Does the horn work?

There is an item on the steering column called the 'clock spring'. This enables all the switches on the steering wheel to make contact when the wheel is being turned. You might consider that area.

 

I have known that if the front wheels are turned by something to far in one direction quickly it can damage the clock spring.

 

I don't think this has anything to do with the steering wheel controls or clockspring. My guess is that the COMAND unit itself is defective, but it could also be a wiring problem. Does the radio come on when you turn on the ignition or do you have to press the power button? If you have to press the power button, that means that COMAND is not communicating over the CAN bus. Like I said, that could be inside the unit, or a wiring issue.

 

The COMAND unit only turns on (or off) by manually pressing the COMAND unit's power button. Your comments ring true, in my mind, but not sure how to isolate this between a wiring problem or an overall defective COMAND unit problem. I wouldn't completely discard the idea of replacing the entire COMAND radio with an updated Android-based unit. But, I would hate to later find out I also have a wiring issue. Thank you for the reply!

 

Update 7/2/2018 - Took vehicle into local dealership and they defined all of the related steering wheel control/COMAND radio issues and have an update. All of the issues come down to one thing. The factory-installed iPod kit shorting out and causing all of the issues with these different components on the network. To fix - they say they will have to remove the iPod kit and then rewire the CAN for a cost of $750-$800. Sounds pretty pricey (to a Scotsman like me) and asked if I could just replace the factory COMAND unit with an Android/Bluetooth based unit and they said it wouldn't fix the issue due to the iPod kit being separate from the COMAND unit. Open to ideas, but will most likely live with the unthinkable effort of reaching a bit further for the manual radio controls for volume/channel selection. It's the inability to answer/hang-up phone calls from the steering wheel that is most annoying/concerning.

Thanks all for your replies and suggestions. They are very appreciated!

 

Can you take it to a good audio shop that is familiar with the MB CAN system and have them give you an estimate. I just do not trust much of what the Stealerships do, especially when it come to MB audio.

 

Removing the factory iPod inter face is not difficult. All you have to do is pull the radio out and remove the iPod interface's wiring harness from between the radio and the car's wiring harness. You will have to unplug the fiber optic from the ipod harness and plug it back into the car's harness. Here's all the WIS docs you need to do that:

Benzbits: W209 iPod Interface

 

I can definitely take it to a local shop which has an excellent reputation. I contacted them, originally, but they stated they didn't have the specific diagnostic tool to troubleshoot the CAN wiring or connections - which they suspected (correctly) was part of the issue.

I purchased the vehicle from a full-fledged (out-of-state) Mercedes dealership last month and can't believe they would knowingly put a car on their lot with so many things non-functional. These items have NEVER worked since it was shipped to me and although I test drove it and had it inspected by an independent shop before purchase - neither the inspection shop or the dealer disclosed these issues.

I'll give the dealership a call and explain to them the dissatisfaction with these items not working and press them to cover the cost of repair or, at a minimum, split the cost. But, I fear the dreaded "AS IS" clause of purchasing a used vehicle will work against me. Doesn't hurt to ask.

 

Rodney - you (and others) are the reason I absolutely LOVE these forums!! I'm more than capable of taking the radio and harness out when provided with the right instructions and these links are absolutely fantastic!! Thanks so much. I'll make sure to provide an update as I either get the original dealership to cover the cost of repair or take on getting this fixed, myself.

I asked the dealership if we could simply replace the iPod kit, instead of removing it and redoing the CAN wiring, but they stated these kits are no longer available. Is there a site where these types of kits (with the iPod connector) might be available on the secondary market? With the connector being broken, I'm almost sure the "short" is likely there. Didn't find anything on eBay.

 

I was able to find an OEM iPod interface wiring harness available on walmart.com (https://www.walmart.com/ip/Mercedes-Benz-OEM-iPod-Interface-Wiring-Harness-5V/277680367). It wouldn't be as simple as swapping out the existing wiring harness (with the broken connector) with this unit, would it?

 

Before buying a "new' harness, you might try pulling the radio out to see what's going on with yours. The iPod interface works by "inserting" itself between the car's wiring harness and the radios. Looking at this diagram:

http://benzbits.com/w209/ipod/Retrofit iPod interface wiring harness.pdf

When installing it, you unplug the car's wiring harness from the radio, then plug it into #12 on the iPod harness, then pug #14 on the iPod harness into the radio. All wiring is pass-through except for the AUX input line which is re-routed to the iPod interface, and the MOST fiber optic lines which are "split" to the iPod interface to maintain a complete "ring", thus the reason why those have to be manually removed from the car's harness and inserted into the iPod interface harness.

The CAN bus wiring is (I think) just run in parallel inside the harness. The CAN bus wiring is a pair of brown wires, one solid brown and one with a red tracer stripe. They are on pins C1 and C2 of the connector - here's the wiring diagram for them:

http://benzbits.com/Audio10PinOuts.pdf

Just check the iPod harness to make sure there are no obvious problems with those CAN wires. These will also be routed down the other part of the harness that connects to the iPod interface itself, which is usually installed int he "cage" under the passenger side footwell (pull the carpet down from under the dash and you'll see he cage there held in place by a few plastic nuts).

Oh and one big warning: Do NOT turn on the ignition with the upper control panel (the one with the "airbag off" light) disconnected. This will trigger an SRS error that has to be cleared with an appropriate scan tool. Some people are more comfortable disconnecting the negative battery lead when doing electrical work, but that's not 100% necessary.

Hope that helps!

 

Rodney,

Again, I can't thank you enough for the information you're providing. This most definitely helps.

The reason I'm thinking about the iPod interface harness is that the existing iPod connector (for older model iPod/iPhone 5 and before) is all mashed up and mangled. I'm suspecting the short may be occurring within the "connector" and replacing the relatively short iPod interface harness/connector shown on WalMart's website (https://www.walmart.com/ip/Mercedes-...s-5V/277680367) looks clean and easy.

Despite the description being a "harness", the WalMart picture doesn't look like a "harness", but rather a simple RJ45 jack on one end and the Apple iPod connector on the other. Perhaps, picture and description aren't lining up, though.

I'll take a picture of the existing connector in all its mangled glory when I get a chance and post it on this thread.

-lzrae

 

I don't think the iPod 30-pin connector would be the problem here. The iPod interface module is what communicates over the CAN. There is no CAN communication in the iPod cable itself. And I don't think problems at that point could cause CAN bus interference. This would be easy to test. Just access the iPon interface module (in the passenger footwell) and unplug the iPod cable (I think it uses an RJ-45 connection). If that fixes it, it is that cable. If not, it's probably the iPod module
s wiring harness at the back of the radio.

 

Oh, and unplugging the iPod cable doesn't change things, try unplugging the the wiring harness from the iPod interface module. If the radio still misbehaves, then it's definitely the iPod wiring harness.

 

Disconnected the iPod cable's RJ-45 jack from the iPod interface module - no change in behavior.
Disconnected the iPod Interface module from the wiring harness - no change in behavior.

I'll be checking the wiring harness/radio connections next.

 

So, now I've got the radio, climate control unit, etc. removed from the dash. The iPod harness wire, however, looks different than what I found in the iPod retrofit diagram (http://benzbits.com/w209/ipod/Retrof... harness.pdf). I uploaded a video on YouTube video showing what I found behind the radio.

There is a molded plastic splitter that doesn't appear in the diagram. Any ideas/suggestions to remove and bypass the iPod harness (indicated in the picture with the green plastic prying tool)?

 

Yes, you have to remove that "splitter". Go to 0:23 in your video. That's the iPod connector plugged into the vehicle wiring harness. You have to disconnect that. Also, the pair of orange fiber optic cables will still be plugged into the other end of the iPod harness (that you unplugged from the radio). You have to disconnect those and reconnect them to the vehicle side of the harness.

 

I guess I want to make sure I have a clear understanding of the "end-result" wiring configuration.

It was my expectation that the entire iPod interface wiring harness would be removed. If that's the case, then the molded plastic "splitter" as well as the separate bundle of wires that are wrapped together in the iPod interface wiring harness would need to be removed. Is that correct?

So - next steps:

1. From the iPod interface wiring harness, remove plastic splitter connections from both sides of the (2) connectors (COMAND and vehicle side) of the vehicle wiring harness.

2. From the iPod interface wiring harness, remove the additional bundle of wires (mix of brown/red) from both sides of the (2) connectors (COMAND and vehicle side) of the vehicle wiring harness.

3. Disconnect pair of orange fiber optic cables from iPod harness and connect them to vehicle side connector of the harness.

Frankly, I didn't expect the iPod interface to take up so many connections in the COMAND radio connector. I also didn't expect to be required to remove each individual wire from the connectors, but the iPad interface doesn't seem to have a simple multi-wire connector to simply pop out.

I'll definitely be taking pictures and labeling the wires as I go through this - just in case I have to put it back together again.

 

What you call the "splitter" does not com apart. You've already disconnected one end of the iPod wiring harness from the radio, now just disconnect the other end that is plugged into the car's side of the radio wiring harness:

After that, you will need to remove the orange fiber wiring from the iPod harness and reconnect it to the car's wiring harness:

Basically, the iPod harness has two ends. One looks just like the connector on the back of the radio. It's plugged into the car's wiring harness (the first photo, the right side of the harness in your video). The other looks just like the car's wiring harness and plugs into the back of the radio (the second photo, the left side of the harness in your video that you have already unplugged from the radio).

 

SUCCESS!! I should have known I was over-thinking the complexity of the harness! I had it nearly completed all along. Steering volume/channel controls work, time/clock can now be set, GPS following car properly - pretty much everything on the punch list! Rodney - I can't thank you enough for the guidance and expert instructions you provided. If I were to do it all over again - knowing what needed to be done - I don't think it would take more than a 1/2 hour and the dealer was quoting me $750-$800 (all labor) to do this work. You saved me some cash, for sure!

I hope to pass along the favor to other MB owners, if I'm able. Great to know you are all out there to help wanna-be DIY-ers like me!

 

I am glad to hear it's all good now! My guess is that the CAN bus wiring in the iPod harness is the problem. It's two wires - look back at my post #13 for the diagram and wire colors. It could be shorted or broken wires, or just a bad pin in the connectors. I'd fix it an re-install it, or sell it.

 

I am glad to hear it's all good now! My guess is that the CAN bus wiring in the iPod harness is the problem. It's two wires - look back at my post #13 for the diagram and wire colors. It could be shorted or broken wires, or just a bad pin in the connectors. I'd fix it an re-install it, or sell it.

 

Oh, so close to perfection, but alas, my work on the radio may have now created another problem.

My top had been open during my work on the radio/iPod harness and now it won't close. The connector to the automatic opener on the center console is plugged in - but nothing happens when I press the button to close the top. I briefly see the "Top in Operation" message on my center dash for 3-4 seconds and then it goes away with no movement from the top.

I disconnected the negative terminal connector from the battery while I worked on the radio unit. Could that have reset something that requires additional steps to re-enable?

Of note - there was a loose connector when I first removed the radio. It had a pair of wires (red/yellow and brown/yellow) and seemed all by its lonesome back there. I saw no associated connections from the COMAND, climate or control modules that would pair with this loose connector.

Once all of the radio accessories and GPS/NAV systems began working, I didn't bother to mention this in my previous post and assumed it was not required.

Now, I'm wondering if that loose connector behind the COMAND radio unit is associated with the automatic top - but that makes no sense to me.

Any thoughts/suggestions for troubleshooting or resolving this issue?

Thanks!!

 

No, that's not related to the soft top control. I think that is part of the wiring used for the optional factory cell phone interface.

I suspect you disturbed the wiring on the switch when you removed the center console panel.

 

I read some threads about disconnecting the battery causing issues with automatic top functionality and requiring some kind of reset or resynchronization. Is that a possibility? Any suggestions on diagnostic tests to try to isolate exact cause?

 

Got it fixed! I simply rolled the front and back windows all the way up and then tried to close the top and it worked!

I'm suspecting the automatic top expected to perform the automatic roll-down of the windows before closing the top and threw an error when it found the windows couldn't be rolled-down (because they were down to begin with).

In any case, looks like catastrophe averted! Thanks, again, for all the help!

 

Ah, yes, if the windows are not synchronized, the top won't work. Good catch! Another test to see if it's the top or the switch is to do the double-tap-and-hold (or double-pull-and-hold) to see if it operates with windows. If that works, then the switch is working.