Connecting J1708 /J1587 Vehicle Data Bus Connections
9-10 80-JB400-1 Rev. D
MAY CONTAIN U.S. AND INTERNATIONAL EXPORT CONTROLLED INFORMATION
Connecting J1708 /J1587
1. Start the vehicle and verify that the truck is in good working order and displays no dash
faults.
2. Verify that the engine ignition switch is OFF.
3. Locate the engine data diagnostic connector.
see Nine-pin Data Link Connector Pin Callouts on page A-10 for more info
• The data source wires to the engine data diagnostic connector are a twisted pair that
should remain twisted after the installation is complete.
• Consult the manufacturer’s wiring diagrams to identify the wires (some are marked
DATA+ and DATA- or D/L+ and D/L-, and some are marked with numbers or colors).
• Note which wire is plus (+) and which is minus (-).
• To avoid confusion, cut and splice the positive wires first and then the negative wires.
Because there usually is not much slack in the engine data diagnostic connector
wires, be careful in cutting and splicing to them.
4. Splice the brown J1708+ wire from the accessory cable to the DATA+ wire of the engine
diagnostic connector. Reconnect the wires.
J1708/J1587 DATA LINK+ (PIN A)
J1708/J1587
DATA LINK- (PIN B)
J1939
DATA LINK- (PIN G)
J1939 DATA LINK+ (PIN F)
MCP
Accessory Cable
Butt Splice
Data Link-
Data Link-
Data Link+
Data Link+
To vehicle
datalink
J1708-
J1708+
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