J-Box Temporary Repair

The Concours J-Box has a couple of known problems, the relays fail and the solder joints fail.

The schematics of the J-Box are shown for pre-'94 and post-'93 Concoursai courtesy of Guy B. Young (no relation). If you're on the road, or in your garage trying to confirm that the J-Box is the problem, this might help diagnosis and temporary repair.

Pin 8 on the JBox connector was unused, so I scrounged in the junk box and came up with a female spade connector with a 6" piece of wire on it to install in the connector. Wrapped electrical tape onto the wire end.

First, Pin 8 provides a switched 12V output through the Headlight Fuse, for anyone who needs it. My real purpose was to circumvent JBox failures while on the road.

1) Main Relay Failure

If the lights are out, except the turn signals, and it won't start, it's probably the Main Relay dying. As an added benefit with the newer Concours wiring, if it was running, the motor stops. With the older Concours wiring, failure of the main relay does not interrupt the ignition. To confirm that the Main Relay is the culprit, with the ignition switch on, there would be no voltage at either Headlight Fuse pin.

To fix this on the road, first pull the 10A Accessory fuse and replace it with the SPARE 30A Main Fuse, found under the JBox cover. Then run a temporary wire from the rear positive accessory lead and splice to the Pin 8 wire on the JBox, start up and ride home. Use the kill switch to stop the engine, then pull the temporary wire and turn off the ignition.

2) Starter Relay Failure

If the rear lights are on but it won't start, the Starter Relay has probably croaked. To confirm, with the ignition on and the starter button pressed, there would be no voltage at JBox pin 13, the Y/R wire.

To start the engine, with the ignition on, briefly poke the short wire from JBox pin 8 into pin 13 on the JBox, and the engine should start. (Or stick a screwdriver across the solenoid terminals.)

3) Headlight Relay Failure

If everything else but the headlight is working, it's probably the Headlight Relay. Confirm by seeing no voltage at JBox pin 9, the BL wire, when the engine is running.

Poke the short wire from JBox pin 8 into pin 9 and the headlight should come on. (Or ride home in the daylight.)

These steps are untested but I'd rather have some plan than no plan when my damn JBox dies on a trip someplace. At least I can use the voltmeter for something. And the little wire stub hanging down from JBox pin 8 didn't cost anything - sometimes the best things in life are free.