What is the diagnostic connector for on a 97 HR Navigator

[MichaelU295]

I found a small rectangular box "Diagnostic Connector" at the driver footwell. What is it for? My engine is all mechanical Cummins 6CTA 8.3. I would think that the Diagnostic port is for newer electronic control engine.

Thanks,
Michael.

[MSHappyCampers]

That sounds like the OBDII port Michael. Maybe 1" x 3" or so?

[clyon51]

It’s a diagnostic port. Most heavy diesel trucks in North America use two basic protocols for diagnostics, J1708 and J1939.

J1708 is an updated version of J1587, it is used on older vehicles and usually is used on a 6 PIN round diagnostic port under the dash on the drivers side.
So take a close look, I’m sure it’s a J1708 Connector.

There are plenty of electronics on ‘97s.

[ElvistheKing]

It’s possible it’s for the ABS, I too have the 6C8.3, my RV is a bit weird I think it must have been just about the last one out of the factory before they moved to the ISC as a lot of the documentation (and the diagrams of fuses, etc. refers to ISC) when I first got it I had a look under the dash, saw a diagnostic connector and thought “great” so went out and bought s silverleaf, plugged it in and of course got virtually nothing, it was only when I got lower down did I notice that it was labelled as ABS and the space marked “engine diagnostic was just an empty hole.

[veraken]

I have the same engine. When I contacted Cummins and asked about the OBDII port, I was told there is none listed for our engine. If you haven't already done so, go to https://quickserve.cummins.com/info/index.html and register you engine (you will need to know your engine serial number). It's a great source of info.

[NHRA225]

Surprise !
If your Coach is all Mechanical there is no OBD Port.
The Plug your looking at is Most Likely the Diagnostic port for Your Allison Transmission.