Make sure the panel does not have a ground fault issue. The best way to tell is to check the following:
Take a voltage reading from aux power positive to Earth ground.
The voltage should read - 6.7VDC.
If the voltage is lower or higher than -6.7VDC, a ground fault is present.
The panel may indicated this trouble if it is turned on.
If the voltage is 0VDC - the ground fault condition is on the positive side of the panel
If the voltage is 13 VDC then the ground fault is on the negative side of the panel.
Leave the volt meter accross the terminal and start disconnecting wires until the voltage goes to -6.7VDC