[Vwdiesel] Using EQUUS OBD II Reader

[Paul]

Hey pavneet,


Quick Diagrams first:

OBD-II communication stack:
                  -------------
Application Layer | SAE J1979 |   High Level protocol
                  -------------
Datalink Layer    | ISO 9141  |   Low level protocol
                  -------------
Physical Layer    | ISO 9141  |   Connector electrical specifications
                  -------------

VAG Communication Stack:
                  ------------
Application Layer | KWP1281  |   High Level protocol
                  ------------
Datalink Layer    | ISO 9141 |   Low level protocol
                  ------------
Physical Layer    | ISO 9141 |   Connector electrical specifications
                  ------------

So,
	My car(03 golf tdi) supports both stacks.  It is mandated that all vehicles sold in the US since 1996 must support obd-ii.  So, you'r car should support obd-ii.  The vag stack has actually been around longer than obd-ii so it sould most definately be supported by you'r car.  

But there is a significant difference inbetween the high level protocols SAE J1979 and kwp1281.  The vw scan tools along with the vag-com use the KWP1281 protocol, where as standard obd-ii scan tools use the SAE J1979 protocol.

The obd-ii scan tool will let you get some, but not all of the diagnostic trouble codes(dtc's) from you're car.  They will also let you read some, but not all of the sensors in you'r car.  And you should be able to clear the code from the car also.

The vag tools are needed if you wan to play with settings like the egr duty cycle or to set you're timing after changing the timing belt.

I don't have a vag-com, but may people swear my them.  I do have a obd-ii reader and it does communicate with the ecu, but new car=no touble codes.. I can read some sensors, and the return values are as expected.

paul



On Mon, 29 Dec 2003 09:47:35 -0500 (EST)
Pavneet Arora <pavneet_arora at waroc.com> wrote:

> Anyone figured out a way of using this reader:
> 
> http://www.iequus.com/item.asp?cid=10&pid=3100
> 
> to interface with their VW (Ours is a 1998 Jetta TDI)?
> 
> I can't imagine that the VW plug would be the same standard OBD II plug
> ;-)?  After my fuel filter/air in the fuel line fiasco I have the Check
> Engine light staying on.  I already have the above OBD II reader (which I
> used on our Contour/Mondeo).
> 
> Many thanks again.
> 
> ----
> Pavneet Arora
> 
> waroc informatik
> Strictly high-end audio and home cinema.  Without the attitude.
> 
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