How does the radio talk to the speedometer cluster? - BMW Luxury Touring Community
 
LinkBack Thread Tools Display Modes
post #1 of 13 Old Jan 30th, 2020, 4:08 pm Thread Starter
Member
 
Join Date: Jan 2020
Posts: 53
How does the radio talk to the speedometer cluster?

08 LT.

When I bought the bike, the radio was good but by the time I got home (1000 mile ride) it was dead. No lights on the radio at all. The dash said NO RADIO and it wouldn’t turn on or off.

I bought another radio from the junker, just the radio, not the control buttons. I took apart the control buttons and cleaned them. There was no sign of water inside.

I had a good week with it then NO RADIO came back. This time, the radio would turn off and on and otherwise function.

I had some cross country rides to do and didn’t mess with it. I use the AUX input and plug in to the headphone jack. As long as I leave it on the correct input, the controls and radio work fine for this but I can't turn off and on the speakers when it's in this state. The control buttons all work, regardless of the NO RADIO message.

After storing the bike for the winter with the battery removed, I now find the radio display now turns on saying BMW, and then finally AUX, but none of the 8 center buttons do anything. Volume control does not show volume changes. I can't turn off and on the radio any more. I'm not sure where to start.

Also, I've got a problem with the EHCS where it won't activate after riding. If you turn the ignition off and back on, however, it works just fine. I've sort of gotten used to this small problem but I'm not sure if it's related.

Last edited by 08ltcolorado; Jan 30th, 2020 at 4:25 pm.
08ltcolorado is offline  
Sponsored Links
Advertisement
 
post #2 of 13 Old Jan 30th, 2020, 9:19 pm
Wrencher Extraordinaire
 
jzeiler's Avatar
 
Join Date: May 2004
Location: Hazel Green, AL, USA
Posts: 13,658
Re: How does the radio talk to the speedometer cluster?

Sounds like some gremlins are loose in your bike. The radio really needs to match the controller (part wit the buttons) so I hope your used radio was from an 05 and up bike. The communication path is on the I-K Bus from the controller to the dash.

The EHCS controller only checks if you are in neutral, side stand up, stopped and bike level (alarm sensor) but it does communicate with the dash on the I-K Bus to display one of three warning symbols on the LCD so there could be a connection. I have never seen this issue with the EHCS, so your may be a first.

John
2009 K1300GT Red Rocket
2009 R1200GS (Gone)
2005 K1200LT Ocean Blue Blue Wizard 114 K and counting...
2006 Bushtec Turbo+2 Spell
2004 330 Ci Convertable
K4AN

Have ridden a Motorcycle in all 48
But lack DE, MA, RI and CT with the 2005 LT

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
jzeiler is offline  
post #3 of 13 Old Jan 31st, 2020, 6:36 am
Senior Member
 
Scimitar's Avatar
 
Join Date: May 2018
Location: Gloucester, England
Posts: 175
Re: How does the radio talk to the speedometer cluster?

The I-Bus is the answer you are looking for. On startup, the I-Bus controller known as "MID" (inside the display) polls the bus asking to know who is listening. Devices respond with their type and in the case of the radio and the CD changer, keeps reporting in every few seconds. If the messages stop for any reason, then the controller thinks that there is no radio and reports as such. Your issue could be in the stingray unit, you need to test by substitution if you can find a matching one. First I would look at the circuit diagam though and check that all the I-Bus connections are sound. It is a single wire which goes to the diagnostic connector and the radio / cd changer and display on the diagram. Maybe purple / white, can't recall.

If you know a bit about it, you can use some software called Navcoder with a simple interface to monitor what is going on to diagnose it.

Previous username - ajlelectronics
Scimitar is online now  
 
post #4 of 13 Old Feb 5th, 2020, 9:00 pm Thread Starter
Member
 
Join Date: Jan 2020
Posts: 53
Re: How does the radio talk to the speedometer cluster?

Quote:
Originally Posted by jzeiler View Post
Sounds like some gremlins are loose in your bike. The radio really needs to match the controller (part wit the buttons) so I hope your used radio was from an 05 and up bike. The communication path is on the I-K Bus from the controller to the dash.
Luckily the radio was from a 2009 and is visually identical to the (hopefully) original one. It came with the entire stingray.

Quote:
Originally Posted by jzeiler View Post
The EHCS controller only checks if you are in neutral, side stand up, stopped and bike level (alarm sensor) but it does communicate with the dash on the I-K Bus to display one of three warning symbols on the LCD so there could be a connection. I have never seen this issue with the EHCS, so your may be a first.
I think there may be a problem with the i-bus as the lightning bolt symbol is permanently displayed on my dash from the EHCS. The EHCS works after startup, and so does the radio. I think the i-bus could be the common point of failure if it is part of the EHCS controller's interlock.

Quote:
Originally Posted by Scimitar View Post
The I-Bus is the answer you are looking for. On startup, the I-Bus controller known as "MID" (inside the display) polls the bus asking to know who is listening. Devices respond with their type and in the case of the radio and the CD changer, keeps reporting in every few seconds. If the messages stop for any reason, then the controller thinks that there is no radio and reports as such. Your issue could be in the stingray unit, you need to test by substitution if you can find a matching one. First I would look at the circuit diagam though and check that all the I-Bus connections are sound. It is a single wire which goes to the diagnostic connector and the radio / cd changer and display on the diagram. Maybe purple / white, can't recall.

If you know a bit about it, you can use some software called Navcoder with a simple interface to monitor what is going on to diagnose it.
I took a quick look and found a white wire in the harness that has pulled out of its connector. I'm going to reconnect it and see what happens. I'll report back in a week or two. You may have solved it.
08ltcolorado is offline  
post #5 of 13 Old Feb 6th, 2020, 12:50 pm
Wrencher Extraordinaire
 
jzeiler's Avatar
 
Join Date: May 2004
Location: Hazel Green, AL, USA
Posts: 13,658
Re: How does the radio talk to the speedometer cluster?

Quote:
Originally Posted by 08ltcolorado View Post
Luckily the radio was from a 2009 and is visually identical to the (hopefully) original one. It came with the entire stingray.



I think there may be a problem with the i-bus as the lightning bolt symbol is permanently displayed on my dash from the EHCS. The EHCS works after startup, and so does the radio. I think the i-bus could be the common point of failure if it is part of the EHCS controller's interlock.



I took a quick look and found a white wire in the harness that has pulled out of its connector. I'm going to reconnect it and see what happens. I'll report back in a week or two. You may have solved it.
I show the I Bus wire as white with a violet stripe.

John
2009 K1300GT Red Rocket
2009 R1200GS (Gone)
2005 K1200LT Ocean Blue Blue Wizard 114 K and counting...
2006 Bushtec Turbo+2 Spell
2004 330 Ci Convertable
K4AN

Have ridden a Motorcycle in all 48
But lack DE, MA, RI and CT with the 2005 LT

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
jzeiler is offline  
post #6 of 13 Old Apr 3rd, 2020, 11:05 pm Thread Starter
Member
 
Join Date: Jan 2020
Posts: 53
Re: How does the radio talk to the speedometer cluster?

So I found a few problems with my wiring. There is a 2pin connector that goes from the radio to the front of the bike. It has a green and black wire. It runs back to the part of the radio with the dial. I'm not sure what that's called. The comms unit?

Anyway it looks like it's for load relief relay. One of the wires was broken completely off, so I repaired that connection. Didn't help the radio at all. This is the wire I was thinking of earlier.

Next, I found the connection from the radio harness going back to the rear passenger intercom had cracks in the insulation near the connector. I repaired that connector and wires. I've never used the intercom but I'm sure it sounds better now.

Then, I started looking at the ibus wire. The wire is white/purple and runs along with the rest of the power and ground wires for the radio unit. I call it the radio power connector. It's all on one plug. There's also a purple/red wire that runs to the instrument cluster too, and I'm pretty sure it's not related to the ibus since it stops at the cluster but is used for some sort of data.

I took apart the radio harness and did a resistance check on the white/purple and purple/red wires. It looked good. I understand this test doesn't really replicate a wiring problem that happens under load. But I did check the wiring for signs of cracks or damage and it all looks good inside the radio harness.

Looking further down the schematic, there is a common point of failure for the EHCS and radio ibus wiring. The ibus wire for the EHCS splices with the radio's ibus wire after the radio power connector but before reaching the instrument cluster. They are also all jumpered to the diagnostic connector. Luckily, these two systems I am having trouble with appear to be the only two systems that utilize an ibus connection to the instrument panel and diagnostic connector.

I will probably start by disconnecting the EHCS module completely to see if that resolves the radio problem. I suppose it could be faulty. Once it's been disconnected I will check resistance on the ibus wires running back to the cluster, and also to the diagnostic connector.

I don't have a clue where the EHCS controller is, I assume it's under the seat somewhere. So that's what I'm working on next. Once I find it, I'll post another update.

Thanks for all your advice so far, it's very helpful!
08ltcolorado is offline  
post #7 of 13 Old Apr 3rd, 2020, 11:25 pm
Senior Member
 
Join Date: Dec 2017
Location: Brisbane Australia
Posts: 393
Re: How does the radio talk to the speedometer cluster?

The EHCS controller is mounted just under the rear seat on the right side , you should see a thing with two plugs on it, one bigger than the other.
One thing I found after I reinstated the EHCS on my bike is that the stand wont deploy if you hold the brake on at the same time. I made that mistake a couple of times and thought the circuit had failed.
Wazza is offline  
post #8 of 13 Old Apr 4th, 2020, 9:54 am
Wrencher Extraordinaire
 
jzeiler's Avatar
 
Join Date: May 2004
Location: Hazel Green, AL, USA
Posts: 13,658
Re: How does the radio talk to the speedometer cluster?

That line from the EHCS is to generate error symbols in the LCD dash area like the lightening bolt. The EHCS controller checks five things prior to deploying, center stand is not down, side stand is up, bike is in neutral, bike is NOT moving and brakes are not on.

John
2009 K1300GT Red Rocket
2009 R1200GS (Gone)
2005 K1200LT Ocean Blue Blue Wizard 114 K and counting...
2006 Bushtec Turbo+2 Spell
2004 330 Ci Convertable
K4AN

Have ridden a Motorcycle in all 48
But lack DE, MA, RI and CT with the 2005 LT

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
jzeiler is offline  
post #9 of 13 Old Apr 4th, 2020, 12:23 pm
Lifetime Supporter
 
Join Date: Jul 2002
Location: Pelham, AL, United States
Posts: 588
Re: How does the radio talk to the speedometer cluster?

And can be in reverse...

_____________

Kim Thomson
Motorcycle Cigar Smoker
05 K1200LT - The Golden Rocket Ship
91 K100RS - The White Stallion
85 K100 Standard - Big Red
79 R65 - "The Bee" is a buzzin' again!
06 525i - Premium, Sport, Comfort, Xenons
01 E320 4matic

Gone, but not forgotten...
02 K1200LTC - Big Blue (accident at 40k)
88 K100RT - Chocolate (it was brown, melted - fire)
85 K100RT - (wore out)
82 Yamaha Vision - (electrics)
72 Yamaha R5C 350 - (broke trans)
alabrew is offline  
post #10 of 13 Old Apr 5th, 2020, 7:34 pm Thread Starter
Member
 
Join Date: Jan 2020
Posts: 53
Re: How does the radio talk to the speedometer cluster?

Found the ECHS module. Thanks to Wazza!

I did some checks with the multimeter last night.

ibus wire, white/purple
Radio plug -> ground = 700ohms
Radio plug -> diag plug = 0-1ohm
Radio plug -> ehcs = nothing

Diag plug -> ground = 600ohms
Diag plug -> radio = 0-1ohm
Diag plug -> ehcs = nothing

ehcs plug -> ground = 2.5 million ohms
ehcs plug -> radio = nothing
ehcs plug -> diag = nothing

Leaving the EHCS controller unplugged, I see the same lightning bolt icon on the dash as before. It looks to me like the lightning bolt on the dash may be caused by the lack of ehcs ibus signal to the cluster in addition to its normal error message which indicates low battery voltage.

With EHCS unplugged, the radio has the same problem, that is it works for about 5 seconds on powerup and then all the buttons on the handlebars and main control unit stop working. Power cycling the bike brings it back online for another 5 seconds. The radio continues to play whatever you were playing while the handlebar controls do nothing.

So I ran a jumper wire from the EHCS plug in to the radio plug and reconnected the EHCS controller. I got much the same symptoms except, after about 1 minute of power on time the radio controls started working again! EHCS Lightning bolt still there.

Next, I pulled the speedometer cover and checked resistance between the ibus white/purple wire and the radio ibus connector. Also checked it to the diagnostic connector. No continuity on either. So I jumpered from the radio connector, with the EHCS ibus included. Hopefully this brings both ibus signals directly to the cluster. Powering on now, the lightning bolt is gone! The radio has the works for 5 seconds and then after a minute has gone the buttons start working normally.

I noticed the ibus wire has battery voltage even when the bike is off. I've been having an issue with the battery draining on its own so hopefully this helps. It looks like the center stand problem is resolved completely. I can use the center stand after riding, without having to cycle the ignition.

As far as the radio being unresponsive for the first 5-60 seconds of power up, I'm really not sure what could be causing that. Any ideas?
08ltcolorado is offline  
post #11 of 13 Old Apr 7th, 2020, 11:57 pm Thread Starter
Member
 
Join Date: Jan 2020
Posts: 53
Re: How does the radio talk to the speedometer cluster?

I was able to fix the radio not responding for 5-60 seconds. Turns out one of the outside control buttons "MEM" was stuck pressed. I removed the PCB and buttons, finding the switch was physically damaged inside. I ended up 3d printing a new plastic piece and now it's all working.

Thanks everyone for your help!
08ltcolorado is offline  
post #12 of 13 Old Apr 8th, 2020, 4:29 pm
Wrencher Extraordinaire
 
jzeiler's Avatar
 
Join Date: May 2004
Location: Hazel Green, AL, USA
Posts: 13,658
Re: How does the radio talk to the speedometer cluster?

It is nice when you finally find the culprit!!

John
2009 K1300GT Red Rocket
2009 R1200GS (Gone)
2005 K1200LT Ocean Blue Blue Wizard 114 K and counting...
2006 Bushtec Turbo+2 Spell
2004 330 Ci Convertable
K4AN

Have ridden a Motorcycle in all 48
But lack DE, MA, RI and CT with the 2005 LT

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
jzeiler is offline  
post #13 of 13 Old Apr 8th, 2020, 4:36 pm Thread Starter
Member
 
Join Date: Jan 2020
Posts: 53
Re: How does the radio talk to the speedometer cluster?

I've gone across the country twice with the LT and never had all this stuff working. Who knows if I will ever truly use it, but you know it makes me feel good to know that "everything works!"
08ltcolorado is offline  
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the BMW Luxury Touring Community forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in











Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome