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Topic: Another question about diagnostic hook up points  (Read 357 times) previous topic - next topic

Another question about diagnostic hook up points

So I've been wondering about what these are all about. I know about the 9 pin.
Thanks
James and Suzi
1999 U320  36, Cummins M11
Build 5544  Motorcade #17268
Ronan, Montana
2020 Jeep gladiator

Re: Another question about diagnostic hook up points

Reply #1 –
The round one is what my VSMpc hooks to.
1999 40 ft. U-320 wtfe build 5563 Chuck & Lynda's "Rollin' Inn"  2030 watts solar
prev. mh's 71 GMC 5 yrs. 73 Pace Setter 1 yr. 78 Vogue 5 yrs 81 FTX 40ft all electric 18 yrs. 1996 Monaco Signature 3 yrs.
2014 Grand Cherokee Overland
Dream as if you will live forever. Live as if you will die today.  James Dean

Re: Another question about diagnostic hook up points

Reply #2 –
On our '97 the rectangle plug is for a direct contact to the trans. ECM. This is where you can go in and change all kind of settings on the World trans. series along with troubleshooting in depth that don't go through the engine ECM link. The 2 ECM units talk to each other all the time. The triangle is somewhat different than ours but looks similar. Our plug like this is to the ABS computer which those changed from year to year.

Mike
Pamela & Mike 97 U 320

"It's not what happens to you, but how you react to it that matters."
 

Re: Another question about diagnostic hook up points

Reply #3 –
Quote from: Gold Nugget finder –
So I've been wondering about what these are all about. I know about the 9 pin.
Thanks

Left to right is the ALDL connector, CAN terminating resistor and 9-pin J1939 interface.

ALDL is an old GM connector, it's mainly there to support older transmission diagnostic tools.
The CAN terminating resistor is a 120 Ohm resistor in a Deutsch housing.
The 9-pin is the SAE J1939 standard interface that is more popular now for diagnostics.

The ALDL is part of the transmission wiring harness and just connects to the transmission for diagnostics.
The 9-pin has both J-1939 and J-1587 CAN networks. The J-1587 is the older slower standard. The gauges use that. The J-1939 connects to all the other ECMs and would give data from ABS, Trans, or Engine ECMs.
The terminating resistor is just part of the wiring standard. CAN networks wire all ECMs in parallel and have 120 OHM resistors at each end. The other one should be back by the engine and there is another 9-pin connector back there.
1991 U300 Side Aisle 6V92 Silver #3897
2004 U320 40' #6246