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BMW OBDII codes and connectors
A friend of mine has a 5-series BMW, I think it's a 2000. We were
discussing my laptop-based OBDII/CAN code reader that I use on my own car, and how useful it was. He said he's wary of buying one, because he thinks he needs to get one that fits the special BMW round port in the engine compartment, rather than the standard rectangular port under the dash. He thinks otherwise it won't be able to read the manufacturer specific codes in the P1xxx range. What's the truth on this? I've read a few webpages, but there's nothing that says anything conclusively. Some pages say that the dash mounted connector is not really connected to anything on a BMW. Others say that this would be illegal if this were really the case. Yousuf Khan |
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#2
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BMW OBDII codes and connectors
Plug your laptop into his car and show him what is there.
OBD II should see the mfg specific codes, P1nnn, if they are present. Your setup will connect to the data port in the passenger compartment that you use in your car. The OBD II spec says that the data port must be a common type and in a common location. The problem (one of many) with the OBD I system was that every automaker had a different way to extract the codes, and the codes meant different things. The service providers had to go to several different schools and buy lots of different scan tools, and as a consequence the diagnostic tools that ought ot save consumers money actually costed them more because the technicians had to cover huge overhead with gathering data from all of the different implementations of the system. OBD II standardized the implementation. In theory -- actual practice, actually -- the consumer can go out and buy a scan tool and use it on any post-'96 make and model car or light truck. "Yousuf Khan" > wrote in message ... >A friend of mine has a 5-series BMW, I think it's a 2000. We were >discussing my laptop-based OBDII/CAN code reader that I use on my own car, >and how useful it was. He said he's wary of buying one, because he thinks >he needs to get one that fits the special BMW round port in the engine >compartment, rather than the standard rectangular port under the dash. He >thinks otherwise it won't be able to read the manufacturer specific codes >in the P1xxx range. > > What's the truth on this? I've read a few webpages, but there's nothing > that says anything conclusively. Some pages say that the dash mounted > connector is not really connected to anything on a BMW. Others say that > this would be illegal if this were really the case. > > Yousuf Khan |
#3
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BMW OBDII codes and connectors
Jeff Strickland > wrote:
>Plug your laptop into his car and show him what is there. > >OBD II should see the mfg specific codes, P1nnn, if they are present. > >Your setup will connect to the data port in the passenger compartment that >you use in your car. The OBD II spec says that the data port must be a >common type and in a common location. The problem (one of many) with the OBD >I system was that every automaker had a different way to extract the codes, >and the codes meant different things. The service providers had to go to >several different schools and buy lots of different scan tools, and as a >consequence the diagnostic tools that ought ot save consumers money actually >costed them more because the technicians had to cover huge overhead with >gathering data from all of the different implementations of the system. OBD >II standardized the implementation. In theory -- actual practice, >actually -- the consumer can go out and buy a scan tool and use it on any >post-'96 make and model car or light truck. The problem is that it will ONLY show you the engine codes. And that's sometimes useful, but it's a tiny fraction of the amount of information that is there. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
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BMW OBDII codes and connectors
Scott Dorsey wrote:
> The problem is that it will ONLY show you the engine codes. And that's > sometimes useful, but it's a tiny fraction of the amount of information > that is there. Are the formats of the non-engine-specific codes different? Will buying the round BMW plug and attaching it to a laptop be able to display those non-engine codes? Yousuf Khan |
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BMW OBDII codes and connectors
"Yousuf Khan" > wrote in message ... > Scott Dorsey wrote: >> The problem is that it will ONLY show you the engine codes. And that's >> sometimes useful, but it's a tiny fraction of the amount of information >> that is there. > > > Are the formats of the non-engine-specific codes different? Will buying > the round BMW plug and attaching it to a laptop be able to display those > non-engine codes? > > Yousuf Khan All of these codes should be available through the OBD II connector ... http://autorepair.about.com/od/obdco..._1996_year.htm |
#6
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BMW OBDII codes and connectors
Jeff Strickland wrote:
> > "Yousuf Khan" > wrote in message > ... >> Scott Dorsey wrote: >>> The problem is that it will ONLY show you the engine codes. And that's >>> sometimes useful, but it's a tiny fraction of the amount of information >>> that is there. >> >> >> Are the formats of the non-engine-specific codes different? Will >> buying the round BMW plug and attaching it to a laptop be able to >> display those non-engine codes? >> >> Yousuf Khan > > > All of these codes should be available through the OBD II connector ... > http://autorepair.about.com/od/obdco..._1996_year.htm But Scott Dorsey said we won't see all of the possible codes coming out of the standard OBDII ports. You're saying we will. Which is right? Yousuf Khan |
#7
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BMW OBDII codes and connectors
"Yousuf Khan" > wrote in message ... > Jeff Strickland wrote: >> >> "Yousuf Khan" > wrote in message >> ... >>> Scott Dorsey wrote: >>>> The problem is that it will ONLY show you the engine codes. And that's >>>> sometimes useful, but it's a tiny fraction of the amount of information >>>> that is there. >>> >>> >>> Are the formats of the non-engine-specific codes different? Will buying >>> the round BMW plug and attaching it to a laptop be able to display those >>> non-engine codes? >>> >>> Yousuf Khan >> >> >> All of these codes should be available through the OBD II connector ... >> http://autorepair.about.com/od/obdco..._1996_year.htm > > But Scott Dorsey said we won't see all of the possible codes coming out of > the standard OBDII ports. You're saying we will. Which is right? > > Yousuf Khan There is program data that the OBD II port will not see, Scott is 100% correct there. But if there is OBD II data, the OBD II data port will disclose it. That's what OBD II is all about. The Check Engine Light (Malfunction Indicator Light -- MIL -- is the technical term under the OBD II specification) will come on if any of the codes in the table I gave you is stored. Let me restate that, there are codes that might not turn on the MIL, but are in the tables I gave you, the OBD II data port will show them. Any Code that lights the MIL will be shown at the OBD II Data Port, some codes that are shown at the data port might not turn on the MIL. There can be vehicle data that is not OBD II data, and therefore will not be shown via the OBD II data port. If you were into tweaking the program, you might be interested in some of this other data. But, if all you wanted was to figure out why the MIL was on, the data port will tell you why, and will include the P1nnn codes. All '96 and later vehicles sold in the USA (and other countries as far as I know, but don't really care much about) will display the P0nnn codes. These codes are all common among all cars. If the car has a system that generates a code, the same code will be generated by all cars. These codes are P0nnn codes. Some cars will not produce a given P0 code because they do not monitor the system -- an example is the After-CAT O2 Sensor, all cars that have this sensor give the same code, but some cars do not have the sensor so they simply can not produce the code and nobody cares. The P1nnn codes (manufacturer specific, by definition) codes are for systems that some makers employ. In theory, a BMW specific code would be for a system that only BMW monitors. The theory breaks down a little bit relative to these codes though. Example, P1246 and P1260 have different meanings depending on the maker yet the conditions reported would reasonably be problematic for all makers and therefore should be a P0nnn code. Having said that, if you look up a code that appears on your BMW, and the tables say FORD ONLY, or whatever, then that system described on the table is not the one that is asking for your attention on your BMW. Or, the tables are dated, and the code is newly added. Since you have a PC based scan tool, you should have the latest code lists available onboard the PC, or via an update that has not been downloaded. Your PC should give a code along with the text of the problem, P0nnn - FRAMIS VALVE MALFUNCTION. If the Framis Valve is monitored by a P1nnn code, it should still be displayed on the OBD II data port. The whole point of OBD II is that repair centers were fleecing consumers under the OBD I system because they were charging lots of money to simply pull the codes. The rationale they used was that the codes were some sort of secret that required specialized training and unique and costly equipment. To the extent that the automaker's schemes to get the codes was different among different makers, and sometimes different among the same maker but different models -- a Thunderbird might display its codes differently than an F150, for example -- the repair shops had a valid claim to your money. OBD II is a rule to standardize the means of extracting the data and diagnose the data extracted. The whole idea was to allow people to understand what was wrong with the car and do repairs themselves without having to learn the technique to get the data and the meaning of the data they got for all of the different vehicles they might own. I own 5 cars. I have to learn several different ways to get the data, and figure out what the data means, for each of them. OBD II makes it easier for me to fix my cars, once I migrate my fleet to post '96 production. |
#8
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BMW OBDII codes and connectors
In article >, Yousuf Khan > wrote:
>Scott Dorsey wrote: >> The problem is that it will ONLY show you the engine codes. And that's >> sometimes useful, but it's a tiny fraction of the amount of information >> that is there. > >Are the formats of the non-engine-specific codes different? Will buying >the round BMW plug and attaching it to a laptop be able to display those >non-engine codes? I believe that the error codes for the other computer subsystems are available through the OBD II port, but they are not readable by the cheap scanners. In addition there are diagnostic modes available on the ports which allow you to plug in a scanning device and look at realtime plots of all the engine sensor inputs and outputs. This is an absolute lifesaver and a whole lot easier than trying to guess what's happening from an error message that says a sensor is out of range, but not what direction it's out of range, and with no information about the other sensors that aren't out of range. Sadly, the cheap scanning tools don't allow you to use that information either. The problem is that these cars are computer networks on wheels... there is an outrageous amount of automation and a huge number of individual communicating systems, and when _anything_ fails you will be completely at a loss without information from the responsible system. The cheap scanning tool isn't a bad thing to have, but it's not enough to diagnose the vast majority of problems you'll encounter. Now... the good news is that if it's a 2000 model, it's not anywhere near as crazy as a late model BMW. And if it has a manual transmission, you are that much better off because the transmission control system is one of the more nightmarish diagnostic headaches. But this is a car that has microprocessors controlling the interior lights... It's not like the 2002 any more, sadly.... --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
#9
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BMW OBDII codes and connectors
On Apr 11, 3:09*pm, (Scott Dorsey) wrote:
> I believe that the error codes for the other computer subsystems are > available through the OBD II port, but they are not readable by the > cheap scanners. Okay, assume I'm using a PC with OBDII software rather than a standalone scanner. My assumption is that all codes are of the same format, whether they are the standard or proprietary codes on OBDII, so the PC software should be able to at least display the code number even if it doesn't understand what it's about. > In addition there are diagnostic modes available on the ports which allow > you to plug in a scanning device and look at realtime plots of all the > engine sensor inputs and outputs. *This is an absolute lifesaver and a > whole lot easier than trying to guess what's happening from an error > message that says a sensor is out of range, but not what direction it's > out of range, and with no information about the other sensors that aren't > out of range. I believe the real-time sensor plots are available on all cars, it's not just a BMW feature, right? So it would be a standard OBDII feature, rather than proprietary. > The problem is that these cars are computer networks on wheels... there is > an outrageous amount of automation and a huge number of individual > communicating systems, and when _anything_ fails you will be completely > at a loss without information from the responsible system. *The cheap > scanning tool isn't a bad thing to have, but it's not enough to diagnose > the vast majority of problems you'll encounter. > > Now... the good news is that if it's a 2000 model, it's not anywhere near > as crazy as a late model BMW. *And if it has a manual transmission, you > are that much better off because the transmission control system is one > of the more nightmarish diagnostic headaches. *But this is a car that has > microprocessors controlling the interior lights... *It's not like the 2002 > any more, sadly.... Yeah, actually my friend wanted a tool that could even tell him if the windows were opened or closed. Not that he really needs that, but he does like to be able to have full capabilities. Will these proprietary, non-critical codes come through the standard under-dash port? Yousuf Khan |
#10
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BMW OBDII codes and connectors
In article >,
YKhan > wrote: >On Apr 11, 3:09=A0pm, (Scott Dorsey) wrote: >> I believe that the error codes for the other computer subsystems are >> available through the OBD II port, but they are not readable by the >> cheap scanners. > >Okay, assume I'm using a PC with OBDII software rather than a >standalone scanner. My assumption is that all codes are of the same >format, whether they are the standard or proprietary codes on OBDII, >so the PC software should be able to at least display the code number >even if it doesn't understand what it's about. If the PC software knows how to interrogate the other computer systems, it might. But interrogating the ECU will give you only the ECU codes. >> In addition there are diagnostic modes available on the ports which allow >> you to plug in a scanning device and look at realtime plots of all the >> engine sensor inputs and outputs. =A0This is an absolute lifesaver and a >> whole lot easier than trying to guess what's happening from an error >> message that says a sensor is out of range, but not what direction it's >> out of range, and with no information about the other sensors that aren't >> out of range. > >I believe the real-time sensor plots are available on all cars, it's >not just a BMW feature, right? So it would be a standard OBDII >feature, rather than proprietary. The implementation is proprietary. Some folks have reverse-engineered it and so there are third-party devices that allow you to see the information the same way the BMW tools do. Those third-party devices are very, very expensive. >Yeah, actually my friend wanted a tool that could even tell him if the >windows were opened or closed. Not that he really needs that, but he >does like to be able to have full capabilities. Will these >proprietary, non-critical codes come through the standard under-dash >port? They will, if you know how to send the interrogation sequence in order to get the computer that controls the windows to tell you what its state is, and if you know how to read the sequence that it sends back. Software to do this exists, but it's not cheap. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
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