[Gmecm] gm 5300 OBD2 port wiring

[DV Fagan]

Steve,
It is possible that GM is using differential
signalling which requires two leads.  That might
explain the common coloring.  I would assume the
signals are asynchronous meaning start bits should be
discernable on an oscilliscope or serial data link
analyzer.
They might be CAN buss.  It is getting popular.
Dennis
--- Robert Fleming <robert.fleming at sbcglobal.net>
wrote:
> There are 2 UART wires right next to each other with
> the same color.  
>  
> There are also 2 wires that go to the ecm that are
> labelled as class 2 serial data.  It does not say
> high or low.  Anyone know which one goes where on
> the diagnostic link?
> 
> Steve Ravet <Steve.Ravet at arm.com> wrote:
> 
> 
> ________________________________
> 
> From: gmecm-bounces at diy-efi.org
> [mailto:gmecm-bounces at diy-efi.org] On Behalf Of
> Robert Fleming
> Sent: Thursday, March 10, 2005 2:36 PM
> To: gmecm at diy-efi.org
> Subject: [Gmecm] gm 5300 OBD2 port wiring
> 
> 
> I'm looking at a 5.3 swap and am running into some
> problems on
> the OBD2 diagnostic port wiring. It is a 2002 5.3
> and the FSM pinout
> says that pins 14 and 15 are UART serial data and 58
> is class 2 serial
> data. Now I assume at the least the UART serial data
> pins are high and
> low, but the problem is they are both orange and
> black. And does the
> class 2 serial data use the vehicle chassis ground
> as its low? The
> harness that came with the engine had the chassis
> side chopped off, so
> tracing wires doesn't answer the question.
> 
> Any help is appreciated.
> 
> Thanks,
> Robert
> 
> 
> 
> Robert, you might find that the 2 UART wires are the
> same signal in 2
> different cavities. The schematics should show if
> this is the case.
> class2 is referenced to ground. what are you
> swapping into?
> 
> --steve
> 
> 
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