jellymonster

Hi
I have a UK X reg Fiat Brava. Doing a little research from:
http://www.mp3car.com/vbulletin/engi...ompatible.html
I have come to the conclusion that my car does not have a OBD socket (unless someone thinks it should do and can tell me exactly where to find it, I had a look around in the internal fuse box on the drivers side but could not see anything).

Reading the 6th comment on the forum by Cico, he says that there should be (or is) a 'FiatTest socket' which contains three pins. From what I gathered, you can connect Pin 5 (of a spare OBD socket) to Signal Ground (of FiatTest socket), Pin 7 - K Line, Pin 4 - Chassis Ground and Pin 16 - Battery Power (+12v).
If this works, will this be the same as a OBD socket?
If so, how can I then connect this to my car PC?
If not, is it nothing like OBD or slightly different?

Thanks in advanced, and sorry if this is just another one of my brain farts.

MP3Car.com

 

p2psmurf

The Brava does have a 3-pin connector for the engine. It has more 3-pin connectors which are connected to the Abs (if present), airbag, etc.
Wiring it to an OBD2 connector has no effect other than that it is easier to connect a scanner.
You cannot use a generic EOBD/OBD2 scanner, as the ecu's do not support any protocol.

jellymonster

Is there any sort of adapter to turn it into a OBD2 socket that can work as an OBD?

malcom2073

If I'm understanding that right, it would likely not work with standard ELM style tools, but might work with a passthrough device ($300+) to let you talk to your car if you know the correct commands.

__________________
RevFE - Try it, you just might like it.
Carbon - Next Generation Touchscreen Browser
Come join us on IRC: irc.efnet.net #mp3car
Audiophiles make me chuckle as they pad my wallet.

jellymonster

Didn't really understand much of that :S. I'm not so great at this XD.
But from what I gathered, you think it is possible, but I need some sort of expensive device and knowledge of these commands.
Would this device be able to connect to a computer, then is there a program for these commands?

p2psmurf

I doubt if the car will talk to a pass-through device.
It most definetely will not talk to a generic EOBD/OBD2 scanner with or without adapter.
You need a scanner with a matching 3-pin connector and Fiat software to read this one.
However, these are professional scanners with professional prices.

marcel3200

this fiat has preobd ECU. Note that the (e)obd is a subset of the ECU command set. Eobd uses a 16 pin connector found on modern cars. By law, it is required to be able to read certain emission parms using simple tools.

Your fiat doen not have all this. however, via the 3 pin connector you can reach the ecu directly and extract almost anything, ranging from dtc (trouble codes), resetting them to injector timing, diagnostic operation of actuators like injectors etc etc. (The eobd reader cannot do this.)

How i know this for sure ?

Well, i have a Maserati 3200GTA (a fiat after all), which has exactly the same diagnostic connector. The fiat probably has the Marelli IAW49F ECU, mine has the Marelli 4CM ecu, same familiy.

I bought a cable on ebay, (search for Fiat Lancia Alfa Romeo Cherry OBD Diagnostic adapter 2). This is a 3pin to 16pin converter cable.
The electrics of the KL interface follows the ISO9141 standard
From there , i built some electronics to have full access to the ecu.
it is designed around a motorola chip, to interface ISO9141 to RS232

The main ecu's in the italian cars: (Fiat,Alfa,Ferrari,Maserati etc)

engine: Marelli IAW series. protocol kwp2000. slow init K line only
abs: Bosch 5.3 series. protocol KW71 slow init L line. bidir data K line
airbag: TRW series. protocol KW81 slow init L line. bidir data K line.

slow init means that you wake the ECU with a 5 baud address. Every ecu has their own physical address. For example the engine ecu = 0x10, the ABS controller has 0x20, the airbag controller has 0x00. Then the ECU responds
with a identity string at a 'normal' baudrate (10400 or 9600 or 4800 baud).
Now the protocol for message exchange has to be followed.

The idea:

having the xenarc connected to a fanless pc. This pc is running msdos (oh yes...) with a dedicated program written in turbo pascal 6.0 (cause i need the serial interrupts). This way i can read all relevant parameters, output them in good native resolution graphics on the xenarc.

How to find the correct parameters ?

Via groups.yahoo.com, group unidiag and opendiag, you find the ECU technical info. In there (some in italian...) you find the locations in the ECU
to get the right data. So as soon as you have the protocol running, then you can find the correct parms.

I did this to make a repair tool, and the next step is the in car xenarc diagnostics with:

-actual knock
-actual lambda
-various temperatures
-error flags
etc

its fun to do!

rgds
Marcel
The netherlands

jellymonster

Thanks alot for your help. This is very helpful.
Can you also get a MPG reading?

Thanks again
JM

MP3Car.com