May 1, 2001

TT #21 Fuses, Relays, Circuit Breakers & Signal Flashers - Part 1

By: Rob Lowe

Technical Tips #21 


Fuses & Relays, Circuit Breakers & Signal Flashers: (Part 1)

As a result of receiving an E-mail regarding the location of the fuse for the solar panel on a Bounder, I became aware that many owners do not know the location of many of the fuses flashers and relays on their Bounders. Most people know that the 12-Volt Coach (house) power fuses are behind a plate located next to the 110V power panel usually found above the dinette. However, do you know the location of the remainder of the fuses?

The first place to check is your chassis Owners or Shop manuals. Observe all cautions contained in these manuals and if you locate a blown high current (40-60 Amps) fuse, remove the battery cable before changing the fuse. On all chassis there is a block of fuses under the swing-up dashboard. These fuses are for Hazard (4-way) warning lights, brake, backup and tail lights, windshield wiper, heater fan and the like. Most coaches also have the Hazard (4-way) flasher unit on this board. The way that I mentally try to locate fuses on this panel is by asking the following question: Is the function controlled by the blown fuse, a chassis safety related one that would have to be operating for the Bounder to be street-legal? If the answer is yes, then this fuse panel is where I begin to look.

The next fuse location is found under the hood in the Power Distribution Box on Ford chassis and part of Fleetwood' s Central Electrical Panel on the Chevrolet Chassis. It contains the fuses and system relays for the fuel system, headlights, starter, ignition, powertrain control module and blower motor. Many of these systems have a fuse in the relay circuit that controls the system. If that fuse fails, the relay can not activate and the system will not work. I have traced problems to a system, such as the marker and tail lights, replaced the fuse in the under dash panel and still had no marker lights. Further investigation revealed that the fuse protecting the marker light control relay had blown, so that pulling on the headlight switch failed to energize the marker light control relay and the marker and tail lights could not operate. Therefore a thorough check of the fuses in the power distribution box is essential if a chassis related item still does not operate after replacing the circuit fuse.

The third location for fuses is the Fleetwood installed Battery Control Center or the previously mentioned Central Electrical Panel, also located under the hood on most coaches. On the new Freightliner chassis diesel models this panel is located in the area near the Coach batteries or by the inverter. In this box are numerous fuses controlling the "add-ons" supplied by Fleetwood and others, such as the step switch & motor, solar panel, LP detector, ignition signal, radio switch, fog lights etc. Some of these fuses control systems powered by the Coach battery, others control items powered by the Chassis battery. There are a few empty fuse holders connected to the Battery (either Coach or Chassis) as well as Ignition and Accessory key positions so that CB radio, Auxiliary lights or other accessories can be safely (and easily) connected to a source of power. Simply connect your accessory, install the proper sized fuse and you are "in power".

To Be Continued In Part 2


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