TrailMax 8012DT, Manual

Page: 37 / 72

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page 37
8012DT
Maintenance
Measuring Amperage
System amperage is the amperage being drawn by all the brakes on the trailer. The
engine of the tow vehicle should be running when checking the amperage.
One place to measure system amperage is at the BLUE wire of the controller which
is the output to the brakes. The BLUE wire must be disconnected and the ammeter put
in series into the line. System amperage draw should be as noted in the paragraph
below. Make sure your ammeter has sufficient capacity and be sure to connect it with
the correct polarity to avoid damaging the meter.
If a resister is used in the brake system it must be set at zero or bypassed com-
pletely to obtain the maximum amperage reading.
Individual brake amperage draw can be measured by inserting the ammeter in the
line at the magnet you want to check. Disconnect one of the magnet lead wires and
attach the ammeter between the two ends. Make sure that the wires are properly recon-
nected and sealed after testing is complete.
By far the most common electrical problem is low or no voltage and amperage at the
brakes. Common causes of this condition are:
1. Poor electrical connections.
2. Open circuits.
3. Insufficient wire size.
4. Broken wires.
5. Blown fuses (fusing of brake circuits is not recommended).
6. Improperly functioning controllers or resistors.
Another common electrical problem is partially shorted circuits (indicated by abnor-
mally high system amperage). These are occasionally the most difficult to find. Pos-
sible causes are:
1. Shorted magnet coils.
2. Defective controllers.
3. Bares wires contacting a grounded object.
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