Communications Problem Service Required VDS Message

[JohnGarziglia]

The message below has been appearing on my VDS each time I start the car for the past several months. When I press to dismiss it, it goes away for the drive but pops up next time I start the car. It is always shows the Dec 22 / 11:07 AM date/time.

I am told that the ID:50 notation in debug is "BMB: No data fault", where BMB is the Battery Monitoring Board. I replaced the existing two-year old 12 volt battery with an Ohmmu 12v Lithium Battery in mid-December and it may have been on December 22nd. I am now seeing a 12 volt battery resting reading at the fuse panel of 11.5 volts which has bothered me but I have not investigated it further because the car is otherwise running well.

What is the Battery Monitoring Board? Could the 11.5 volts reading be associated with this error message? Should I be concerned about the 11.5 volts resting voltage reading? Any observations or advice are most welcome. Thanks!

 

[slcasner]

Calling @MLAUTO for possible knowledge regarding this problem.

 

[ShawnA]

Hi John,

Sorry for the fleeting memory - Do you have an OVMS3 installed???

On mine the 12 volt reading is 11.2 volts while the car is sleeping...

Shawn

 

[einhalv]

The 11.5-V readout during sleep appears not to be a cause for worry by itself I concluded based on the feedback in this thread:

Storage mode and the 12-V battery

 

[gregd]

Hi John,

Sorry for the fleeting memory - Do you have an OVMS3 installed???

On mine the 12 volt reading is 11.2 volts while the car is sleeping...

Shawn

Hi Shawn,

Mine reads similarly, and it's due to a number of factors that appear to have nothing to do with the 12v battery (or 12v inverter in the 1.5's). That connector that the OVMS attaches to is connected to equipment which is fed from the 12v system above it. You're not looking directly at the 12v system. For that matter, with the architecture of the APS system, there isn't a (singular) 12v system in the car, at least in the way an ICE has one.

But besides that, whether awake or fast asleep, the voltage at the terminals of my 2.0's 12v battery read 13.78v, plus or minus a few hundredths of a volt depending on which meter I use (*). This could be an anomaly with my car - the service staff couldn't explain it, as they thought the car would be relying on just the battery when the car is asleep - but it clearly is not. Resting voltage of a 12v SLA battery is 12.6v, so it's being continually maintained at a "float charge" level.

Anyway, bottom line is that the "voltage" reading you are seeing is normal.


(*) When I got the battery replaced some years ago, I brought some wires and connectors, and asked the techs to connect them to the terminals and bring them up into the accessible area under the hood. The idea was primarily to be able to "jump" the battery if there was a problem, but it's been more useful to monitor the apparently very boring voltage trends.

 

[JohnGarziglia]

Mine reads similarly, and it's due to a number of factors that appear to have nothing to do with the 12v battery (or 12v inverter in the 1.5's). ... But besides that, whether awake or fast asleep, the voltage at the terminals of my 2.0's 12v battery read 13.78v, plus or minus a few hundredths of a volt depending on which meter I use ... bottom line is that the "voltage" reading you are seeing is normal.

Thank you! This is extremely helpful. My angst with the 11.5 volt reading from the car while resting started when I replaced my existing two-year old 12 volt battery with an Ohmmu 12v Lithium Battery in mid-December, and I decided that it was the time to accurately calibrate the voltage reading displayed by OVMS. I even junked a 30 year old Radio Shack multi-meter in favor of a new Fluke meter to insure I was getting accurate readings.

So this past weekend when changing out the winter tires/wheels for the summer tires/wheels (winter tires were a waste in the mid-Atlantic region this year), I took voltage readings at the battery. Both connected and disconnected the reading from the battery is 13.73 volts. So yes, there is a completely different reading in the car itself with my reading in the car being 11.5 volts while resting, and 13.3 volts while awake.

I am still curious what the "Communication Problem Service Required" message always showing the same date/time on my VDS means although I am now not concerned that it relates to the 11.5 volt reading I was getting while the car was asleep.

 

[gregd]

To finish the scenario, my OVMS shows about 13.0v when the car is awake, and 11.3v when asleep, but the battery doesn't budge from 13.78v regardless. Crazy way to wire up an automobile. But if you disconnect the battery from the car, it should settle down to about 12.6v within a few minutes, assuming it's a sealed lead-acid type.

I've gotten the "Communication Problem Service Required" message only once, while I was poking around the VDS diagnostic menu, looking for something. Never found it (and I swear I didn't touch anything dangerous), but in the process things stopped working. I mean stopped. The door latches stopped working (fortunately the windows were down), flapping the charge port door did nothing, the car was frozen other than the coolant pump was running. I assume that the car's computer (the VMS) had crashed / locked up, so I expect it was a different problem than you are having, since your car is otherwise operating.

The fix for mine was to disconnect both connectors to the VMS and reconnect them, which cycled power to the car's computer. It's the silver box under the dash, behind the glove box. Very annoying body position to get there, and it takes some care not to bend or break anything (especially the locking tab!), but it worked. That fixed the "near death" experience (not sure if it was mine or the car's).

 

[JohnGarziglia]

I've gotten the "Communication Problem Service Required" message only once, while I was poking around the VDS diagnostic menu, looking for something. ... The fix for mine was to disconnect both connectors to the VMS and reconnect them, which cycled power to the car's computer. ...

I have tried disconnecting and re-connecting the VMS several times and that has not cleared the "Communications Problem Service Required" message. Still re-appears each time I start up the car with the same date/time. Oh well. At least it is only an annoying message for now.

John

 

[markwj]

To finish the scenario, my OVMS shows about 13.0v when the car is awake, and 11.3v when asleep, but the battery doesn't budge from 13.78v regardless. Crazy way to wire up an automobile.

You are probably aware, but anyway: OVMS is measuring the voltage at the DIAGnostic connector. That is one of the 12v circuits from the DC-DC converter in the ESS. The little 12v battery is a completely different beast, and not connected there at all. OVMS uses a simple voltage divider, and ADC input on the chip, to get the measurement - so probably not particularly accurate (although it can be calibrated).

The VDS can display both the APS voltage as well as the little 12V battery voltage, so the value must be available in the CAN bus messages. Just never gone looking for it. If someone technically capable, with OVMS in their car, wants to help look for it: I am up for the challenge.

 

[gregd]

You are probably aware, but anyway: OVMS is measuring the voltage at the DIAGnostic connector. That is one of the 12v circuits from the DC-DC converter in the ESS. The little 12v battery is a completely different beast, and not connected there at all. OVMS uses a simple voltage divider, and ADC input on the chip, to get the measurement - so probably not particularly accurate (although it can be calibrated).

The VDS can display both the APS voltage as well as the little 12V battery voltage, so the value must be available in the CAN bus messages. Just never gone looking for it. If someone technically capable, with OVMS in their car, wants to help look for it: I am up for the challenge.

Yep, thanks for documenting this. As I said, it's a crazy way to wire up a car...

Given that the 12v battery's float voltage doesn't change, that's going to be a tough one to find. Where in the VDS is the value shown? I wonder how it matches up with my meter readings?

 

[markwj]

Given that the 12v battery's float voltage doesn't change, that's going to be a tough one to find. Where in the VDS is the value shown? I wonder how it matches up with my meter readings?

Given that we are straying off topic for this, I will eMail you directly. If we find anything useful, we can publish here on the OVMS Technical page.

 

[drewski]

Where in the VDS is the value shown? I wonder how it matches up with my meter readings?

ESS->BSM

 

[hanknum]

So, these are the messages I got today (note the battery voltage in the last photo). I last drove the Roadster a week ago. Is my first step to disconnect the VMS?

 

[hanknum]

VMS?

Please help.

 

[marco2228]

Better not disconnect the VMS for the moment. It could corrupt needed files in the system.
Can you enter the diagnostic/service menu? Or is the VDS not responsive at all?
If you can enter the menu, check the SOC menu, at first.

 

[markwj]

VMS?

Please help.

If you have OVMS installed, I can probably help remotely diagnose. You can mail me mark at openvehicles dot com.

 

[hanknum]

If you have OVMS installed, I can probably help remotely diagnose. You can mail me mark at openvehicles dot com.

Yes on the OVMS... I just emailed you Mark.

Thanks a ton.

Henry

 

[markwj]

Yes on the OVMS... I just emailed you Mark.

Thanks a ton.

Henry

Got your email and replied. Looks like VMS is locked up / non responsive.

 

[marco2228]

@markwj is it possible to get a short trace of the actual CAN traffic on the vehicle shell of the OVMS?

 

[markwj]

@markwj is it possible to get a short trace of the actual CAN traffic on the vehicle shell of the OVMS?

Easiest is ‘re start’, wait a few seconds, then ‘re list’. That will show a summary for each ID seen. The ‘re stop’ command stops collecting that data. You can also get a full dump (can log …), but harder to do remotely.