I traded in my old Jeep Cherokee on a nearly new Chevrolet Malibu Maxx. The Jeep was fixing to cost me a bunch of money to keep it on the road. Only time will tell if I made the right decision but at least for now I'm saving a bunch of dollars on gas.
Well I proceeded to get my Malibu road ready and found out it was going to take some work and money. The hatch is aluminum so my portable magnetic light set would not attach to the back lid. There just didn't seem to be any convenient way to mount the lights so I decided to wire in my lights. Being basically cheap, I couldn't bring myself to fork over the $60 or so for a fancy wiring kit with diodes. It's a good idea that if you're not using diodes that you make sure that your Motor Home has its own tow circuit protection. My Malibu lighting system is protected as the car source power is isolated from the RV tow lighting circuit. By selecting one you electrically disconnect the other. Both systems share the common chassis ground.
What follows is how I wired an Ignition Sensor fuse bypass switch and my tail lights for about $30.
Ignition Sensor Bypass Switch Circuit
The Chevrolet owner's manual recommends pulling the Ignition Sensor fuse to avoid draining your battery during towing. A side benefit of pulling the fuse is your odometer will not accumulate any miles. The Ignition Sensor fuse is located in the body control module under the dash and part of the center console on the passenger side. The description alone makes you think it's hard to access which it is for my fat stubby fingers.
I went to Radio Shack and purchased a simple rocker switch and an inline mini fuse holder for $6.00. I took a bad spare mini fuse and scraped off the plastic covering the conductors on the top so I could solder a wire to each terminal.
I have seen this idea a while back in another forum but I can't remember where so I can give the credit. If you don't have a bad one you can blow one by putting the fuse across the terminals of a car battery. Make sure the battery is not connected to the vehicle. Also you may be able to find fuse taps but I couldn't find any locally that would fit a mini fuse avoiding this painstaking fuse soldering job. I ruined 3 fuses before I got it right.
Solder a wire to each side of the mini fuse. Crimp a female quick-disconnect on one of the wires for connection to the rocker switch. Solder the other wire to one of the fuse holder wires. On the other end of the fuse holder crimp a female quick-disconnect. Mount your switch somewhere close to the driver but some place it won't accidentally get bumped and turned off. Attach the 2 wires with blade connectors to the back of the switch. Pull your IGN Sensor fuse and install it in the inline fuse holder. Put your modified blown fuse in the IGN Sensor socket. When you're all done it should resemble my poor excuse of a drawing.
Drawing: Sensor Circuit
Tail Light Wiring
For the Stop, Turn, and Tail lights I used 2 double pole double throw (DPDT) toggle switches (Radio Shack) with a center off position and a four wire connector kit from Ace Hardware. I spent about $20 for the 3 items. I routed the trailer wire from the front bumper through the fire wall and down the interior of the car. At the front of the car I extended the white wire, which was only about 2 feet long, connecting it to a handy chassis ground located behind the headlight. The Malibu's Rear Fuse Block is located inside the car by the roadside rear tail light making it vary easy to get at. After removing the interior access panel, the Rear Fuse Block can be unlatched and turned over so you can see the wiring. Probe the wiring while a helper, my lovely wife for instance, operates the different lights so you can verify the wires. I then put masking tape on each wire marking them so it would be easier to identify after I pulled my head out of the hole. I mounted the toggle switches in the vinyl panel hopefully where they won't get bumped. Being forgetful I also labeled the switches so I would know which switch position was RV or car. Then I cut, spliced, and extended the wires to reach the switches. It makes the wiring job a whole bunch easier if you use Tap-In Squeeze Connectors. They cost about $2.00 for 8 or 10 of them. Last step is to connect female quick-disconnect to all the wires and connect them to the switches.
Wiring diagram before modification: OEM Wiring
Wiring diagram after modification: Wired
Toggle Switch view: Toggle Switch
So far I've taken it out a couple times and my switch setups have worked great. I might have saved some more money on hardware if I'd scrounged around a bit but I needed to get the car ready for a trip. It may not be for every TOAD but for my Malibu I'm sold. Oh yes, I have a portable light set I don't need any more.
Item: 30 Amp Inline Mini Blade Fuse Holder
Part #: Radio Shack 270-1237
Note: A smaller size amperage wire would make it easier to work with but this was the only size they carried.
Item: SPST 25 Amp Automotive Rocker Switch
Part #: Radio Shack 275-730
Comment: Switch can be surfaced mounted or with the included bracket.
Item: DPDT 20 Amp Flip Switch
Part #: Radio Shack 275-710
Comment: I really like the fact that this switch has a center off position that disconnects all circuits.
Item: Hoppy 4 Wire Flat Connector Kit
Part #: Ace Hardware 8038333
Note: Includes 24 feet of the properly color coded wire.
Item: Wire Tap-In Squeeze Connectors
Part #: Radio Shack 64-305
Note: Make it easy on yourself a get a bunch.