J1708 Electrical Connection

[RedSectorA]

Hi,

Does anybody know on which electrical circuit/fuse the J1708 (ECU Diagnostic Connector) is connected on a 2000 HR Navigator.  Currently no current between the power and ground in the dataport.

Thx,

Edited May 23, 2023 by RedSectorA

[DavidL]

I am a little confused, certainly J1708 is a CAN data connection.  There is no fuse on those two wires.

From memory, the J1708 spec says voltage between should be 0.5 - 1.5 volts.

If you aren't familiar with CAN data traffic...go slow because mistakes can be costly.

 

Edited May 23, 2023 by DavidL

[RedSectorA]

4 minutes ago, DavidL said:

I am a little confused, certainly J1708 is a CAN data connection.  There is no fuse on those two wires.

From memory, the J1708 spec says voltage between should be 0.5 - 1.5 volts.

If you aren't familiar with CAN data traffic...go slow because mistakes can be costly.

 

Hi David,

I've worked with OBD2 more than J1708 but pins C and E carry the electrical signal or so I'm told, not the data signal,  but on mine there's nothing.  Normally they are fused, aren't they?

Dan

[DavidL]

I believe there are many wiring schematics posted on this sight in the Downloads directory.

See if yours is there.

 

You can also use a signal tracer on the ground / power wire to see where it goes, and where it stops.

Edited May 23, 2023 by DavidL

[Ivan K]

I have 1A Diagnostic fuse for the ISM/M11 in chassis section of FRB that is always hot.

[vito.a]

What is the basic issue you are trying to resolve?

Have you connected a heavy diesel code reader to the port and does it operate?

[Scotty Hutto]

I had the same issue on my 2006 Dip. The 7.5a fuse for the ECM in my battery bay was blown.  It was in a fuse holder mounted on the sidewall of the battery bay.  A bit difficult to find, since the label had long since lost its ink. 
 

PS - my ECM worked fine and I could read it from the engine bay with Insite; apparently that fuse just powered the J1708 data bus up front. ??? 
 

[RedSectorA]

1 hour ago, Ivan K said:

I have 1A Diagnostic fuse for the ISM/M11 in chassis section of FRB that is always hot.

Will check thank you.

1 hour ago, vito.a said:

What is the basic issue you are trying to resolve?

Have you connected a heavy diesel code reader to the port and does it operate?

  Purchased the coach a few months ago and can't connect to the ECM with my reader.  I also know I have no voltage from the two pins indicated above so it has no power

Edited May 23, 2023 by RedSectorA

[RedSectorA]

53 minutes ago, Scotty Hutto said:

I had the same issue on my 2006 Dip. The 7.5a fuse for the ECM in my battery bay was blown.  It was in a fuse holder mounted on the sidewall of the battery bay.  A bit difficult to find, since the label had long since lost its ink. 
 

PS - my ECM worked fine and I could read it from the engine bay with Insite; apparently that fuse just powered the J1708 data bus up front. ??? 
 

Thank you Scotty, I will check to see if I can find anything but both my data port aren't functional at this time.