A Mini Diagnostic Story by Justin P., CEO
I was working with our tech support team at our facility in Lowell one day when a tractor trailer pulled up for the last pickup of the day. I always look at the trailers to see if there is a liftgate, and, if there is, I look at the front to see if it has one of our liftgate charging systems. This trailer had a Direct Liftgate Charging System—but one of the lights was flashing orange. Uh oh!
When the vehicle is running, both lights on the Direct controller should be green, showing that there is good input voltage from the source and that the liftgate battery is charging. Anything else is a warning that something in the system is not functioning properly.
This particular trailer had one flashing orange light and one flashing green light. The light indicating the liftgate battery state of charge was flashing green, indicating that the battery was at a good state of charge, but not charging. The input source light was rapidly flashing orange, indicating that there was a fault on the input side. In this case, the input was the aux circuit on the 7-way cable.
We explained to the driver that the charging system wasn’t operating. It was his last stop of the day, so he said he could wait a few minutes while we performed our diagnostics to see why the system wasn’t working, and confirmed that the gate had worked all day. Columbus, one of our technical specialists, quickly jumped to the rescue to start the diagnostic process.
The rapid flashing orange light indicates extreme low voltage or an open circuit. Columbus opened the box and checked the fuse, but the fuse appeared to be intact—so it wasn’t an open circuit. Next, we closely inspected the 7-way cord. We discovered that the 7-way socket and receptacle were both worn out, causing high resistance due to loose connections. We also noticed some corrosion within the receptacle.
We tested the circuit by replacing the existing 7-way cord with a new 7-way and both lights on the controller immediately changed to solid green—indicating that there was sufficient voltage to support the charger and that the charger was putting energy into the liftgate battery. We explained this to the driver and suggested he request the 7-way connection on the tractor be replaced.
At that point, the driver asked a good question. Since the liftgate battery indicated that it was still at a good state of charge even though the charger hadn’t been functioning for at least a portion of the day, why did he even need the charging system? The answer is most likely that the tractor pulling that trailer the previous day had a good 7-way connection and kept the batteries at a good state of charge. Also, the Direct system was functioning properly, just not charging due to the faulty cable—and thanks to the Direct, we knew to check the 7-way cable!