hey all,

I got my obd-2.com connector from Alex Peper. Cool for me because the "ISO" protocol is used by Dodge and the Asian cars, so my Acura and RAM both use the same connector.

I think.

Well, it works on the Acura, but won't connect on the 2004 RAM. anyone know what gives here?

 

The '03-04' Dodge Ram with the Cummins uses CANBus which is a different protocol from OBD2. Companies that make OBD2 diagnostic readers should be coming out with updates for CANBus in the near future.
Besides, Dodge addressed this issue by allowing fault codes to be displayed on the odometer readout.

MikeyB

 

hmm. wonder if they made the switch to CANBus for the 2004 model year? the device is succesfully used today on 2003s.

 

Who's your OBD2 reader manufacturer?
I have a AutoXray OBD2 reader and they told me the updates to interface vehicles with CANBus will be out in the near future.

MikeyB

 

and we're still iterating. Did you say that the 04 trucks used CANBus and not obd 2?

 

Yes, the '03-04 Rams with the Cummins uses CANBus.

MikeyB

 

Well, my 02 had a CANBus too, but that had nothing to do with OBD. The 2003 RAMs talk ISO flavor of OBD-2, so the presence of CANBus must not preclude the on board diagnostics. I guess I'm still not sure how to interpret all this, what relationship CANBus has to OBD andwhat OBD support the 04s have that might be differnet from the 03s

 

Is the diagnostic port connector between the '03 and '04 the same? If it is there's a possibility the data pins may have switched on the '04. Or the protocol may have changed.

MikeyB

 

ok I got it solved. for 04, the protocol is no longer ISO but VPW and the diagnostic port connector is still the same. now I'm talking VPW to my truck and all is well. So to clear up the confusion:

1. CAN has not yet replaced OBD2 on the Dodge trucks. The mandate is for mfgs to support CAN by 2008, which means some will support before then, but Dodge has not decided to do this for the early 04s at least. CAN existed on the Dodge trucks even on the 2nd gens ( my 02 had a CAN bus) but this is an internal engine control bus and not related to the use of external scanning tools.

2. For external scanning tools, the 03 from the best of my research (not personally validated) is OBD-II, protocol "ISO"

3. starting in model year 04, the Trucks use VPW for external scanning tools