Near Intersection of I-35 & I-90 Southern Mn. | My guess is that you don't really have Ground at 85. When you test it on the bench you likely do. There is a difference between ground and no power (float). Just because a wire doesn't show 12V doesn't mean it is ground. It might just be disconnected further back.
By using a meter set to resistance or continuity, you should be able to determine if the wire you feel is ground is really ground or not.
I would also use relays for the signal and tail lights. When I did this with a 4440, I used a plastic box with several relays inside it.
The box had a fairly large red wire for 12V constant into the box. This red wire was connected through a fuse to the positive terminal of one of the batteries. I also had a fairly large black wire for Ground for the relays and Ground out of the box.
Internally the red wire split to feed each relay as well as exit out for constant 12V power. The black wire split internally to provide ground to each relay as well as exit for Ground out. A trigger wire was used for each relay to cycle each one to provide tail, left and right signal out. These trigger wires were spliced on the tail, left and right signal wires of the tractor. Another relay could be used for a 12V key switched power out pin source
This meant that all power out came from the battery through a decent sized wire and a fuse. The ground was a solid connection to the battery ground. All supplemental outputs such as the lights and switched power out came through relays rather than impose an additonal electrical load on the original circuits.
I think using a relay as you first planned is the proper approach. That way the key switch trigger for the relay isn't carrying much of an electrical load. The actual load or "work" of running cycling any accessory is handled by a direct connection to the battery through a relay. The electrical load of cycling a half-width clutch might be "too much" for a direct connection to a key switched source. |
Wiring 7 Pin Connector to 4640
