Yes its directly in line with the steering collum, on the underside of the little shelf that is beneath it.,A little cover unclips swinging downwards and forwards to expose it.
Regards Roland Gt Tuning
This is what a 2002 Cooper implements on OBD-II
Service 1 PIDs
00 PIDs supported
01 System tests status
03 Fuel system status
04 Calculated Load Value
05 Engine Coolant Temp
06 Short Term Fuel Trim
07 Long Term Fuel Trim
0B Intake Manifold Pressure
0C Engine RPM
0D Vehicle Speed
0E Ignition Timing Advance
0F Air Intake Temperature
11 Absolute Throttle Position
13 Location of O2 sensor
14 O2 Sensor 1
15 O2 Sensor 2
1C OBD standard
20 More PIDs
21 KM travelled while MIL lit
I have decoded much of the CAN protocol and can read things like each of the 4
wheel-speed sensors as well as the blinker on/off message. (Seriously, everytime
the blinker goes on or off, there is a CAN message sent!)
There are several things going on here and I'll take them one at a time.
I'm reading the OBD-II protocol using an SAE J1979 interface which is also
called ISO15031-5 I got the interface from scantool.net and it's called the "ISO"
interface on that website. It was somthing like $80 or so.
It looks like you are reading the OBD-II protocol using a CAN interface (ISO 15765-4)
We should be able to get the same data, but my 2002 MINI Cooper does not have an
OBD-II CAN interface.
When I discussed being able to read out the individual wheel speeds, I was not
talking about the OBD-II/CAN interface, I was talkig about using the internal CAN
insturment bus. These are two seperate CAN busses, and the internal one does not
go to the OBD-II connector. I tapped into it behind the tachometer cluster on the
steering column. You will not be able to get wheel-speeds from the OBD-II connector
Now, on to the messages you did get. Each PID sends back a message, and the
data is interpreted differently depending on the PID.
For example, the engine RPM is sent back as an integer which is the actual engine
RPM value times 4, so the display program should display the RPM in 1/4 RPM units.
It looks like you got " 010C 810" and I doubt that you were running at 202.5 RPM,
so I think that's right.
You got " 010B 6.54" as intake manifold pressure which is already a decimal
number, so some part of the software converted it for you. Maybe it's in PSI or
something. The raw data is in kilopascals, so a reading of 101 KPa means that your
intake manifold pressure is the asme as atmospheric pressure. 6.5 KPa is really low,
and would probably never happen. OK, maybe when you decelerate from a
high-speed with the throttle slammed shut. So, (long winded, me?) I think it's
probably PSI above atmospheric.
"010E 6" is probably 6-degrees of ignition advance at idle. Probably right.
"010F 82.4" Was it 82.4 degrees inside your intake? Maybe?
"0111 1" Try pushing the throttle and reading it again.
Well, my RPM was actually 810 when the reading said 810 ,it was never 202.5 (that's near stalling). So I think the software is giving me actual readings. As for the 6.4 for pressure, I think this is just PSI. I was stationary for all reading, so no true force was being exerted and shown through other value readings.
I appreciate though that OBD and CAN offer basic values that need manipulation, but i would expect these to be consistent, as the software nor the hardware used here could never intercept all makes and models of car, i.e. OBD data must be standard for all cars, yes?
Interesting that the CAN does not relay all of its data through the OBD port, is this because it is in compatible with that part of the wiring loom, or is it because the CAN is an internal and externally unrequired data collection?
Thanks for your info so far - PS. why did you conenct to the loom behind the tachometer anyway? i also assume you are a qualified electronics technician of some kind to begin on this kind of work with your MINI?
Too many mods to list, PM me if the cat needs killing...
The OBD-II PROTOCOL is standard, but the auto manufacturers choose which
particular values (values are called PIDs in OBD-speak) they want to support.
There are some PIDs that MUST be supported by every OBD-II compliant auto,
but there are very few of them.
The CAN protocol and the OBD-II protocol are VERY different. Nearly incompatible,
but not so incompatible that the geniuses in the automotive industry haven't found a
way to talk OBD-II using a CAN interface.
OBD-II is a request/reply interface. Your software asks "Please send me the current engine RPM" and the engine management computer says "The current engine RPM is 3,250.25 RPM"
The CAN protocol is more like the engine management computer yelling every 10
milliseconds, "RPM=3250.25" to anyone and everyone who is interested in it.
The CAN bus runs between several items in the vehicle:
Insturment cluster (Speedometer etc)
Remote insturment cluster (Tachometer)
Engine control module (ECM)
Steering angle sensor
Transmission control module (GIU) for the automatic transmission.
Since I have a Cooper 5-speed without DSC, I dont have a steering angle sensor
or a GIU so the wiring harness was easiest to access right behing the tachometer.
Well, calling me QUALIFIED is quite a stretch.
I'm a scientist, but I can plow through standards documents, record raw data off an
insturment bus and decode it through trial and error. This link shows what I've decoded so far. Feel free to make use of it if you can.
' 6.4' as a pressure reading means 6.4psi above absolute zero, (6.4psia) .Atmospheric pressure would read 14.7psia, so in effect you are 14.7 - 6.4 = -8.3psig. In other words 8.3psi 'negative' or to be more accurate 8.3psi below atmospheric pressure.This is exactly what I would expect at tickover .Interestingly
if you turn the aircon off (assuming pump was previously engaged) tickover stays the same but depression (vacuum) increases. Why? because in order to maintain auto idle speed stabilisation the reduced engine load means the throttle can shut marginally more, the result more vacuum downstream of the throttle where the 'upstream' map sensor connects.
Regards Roland Gt Tuning
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