Steve Ross

Rx 300 Trailer Wiring

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Does anyone know why the built in trailer wiring harness on a 2001 RX300 would have no power to it after the 'towing' fuse [20A] is inserted?

The fuse is good and there is power to one side in the fuse box. The trailer harness is located up under the tank and has 4 prongs as expected. The ground wire is ok, but no power to the other terminals. Any ideas [or a wiring diagram] would be appreciated.

Thanks, Steve

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Does anyone know why the built in trailer wiring harness on a 2001 RX300 would have no power to it after the 'towing' fuse [20A] is inserted?

The fuse is good and there is power to one side in the fuse box. The trailer harness is located up under the tank and has 4 prongs as expected. The ground wire is ok, but no power to the other terminals. Any ideas [or a wiring diagram] would be appreciated.

Thanks, Steve

"There is power to one side" is not enough. With the fuse inserted there should be power to both sides. You probably know that but the post makes it unclear if it has been checked.

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I have a 2004 RX330 that I just installed the lexus trailer hitch on. The factory wired 4 prong connector has been connected but it is not providing any power to the hitch wiring. This is the same issue Steve Ross was having.

The fuse for the Towing option is in place but I don't think this has anything to do with power not being applied to the connector when the tail lights,brakes or signals are active.

Is there something else that needs to be connected for the factory harness to be active?

Thanks

Allen Patenaude

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I have a 2004 RX330 that I just installed the lexus trailer hitch on. The factory wired 4 prong connector has been connected but it is not providing any power to the hitch wiring. This is the same issue Steve Ross was having.

The fuse for the Towing option is in place but I don't think this has anything to do with power not being applied to the connector when the tail lights,brakes or signals are active.

Is there something else that needs to be connected for the factory harness to be active?

Thanks

Allen Patenaude

The original post was about a RX300 and you have a RX330 which is slightly different. Anyway, you need the converter module which is located behind the driver's side rear seat somewhere. I can't tell you the exact spot, I have a RX300 which has it located in the cargo tray area. Check here for more info about RX330 converter module:

http://www.clublexus.com/forums/rx-second-...tion-block.html

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I just got done removing the back set in my RX330 and found this junction box.

Are there different versions of it?

The trailer hitch connection is plugged into it as well as other connections but no power.

Allen

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I just got done removing the back set in my RX330 and found this junction box.

Are there different versions of it?

The trailer hitch connection is plugged into it as well as other connections but no power.

Allen

I have a RX300 so can't speak from experience about the RX330 converter box but I do understand that there are 2 versions of the module. One is towing enabled and one is towing disabled. See here for more info, post #47 in particular:

http://us.lexusownersclub.com/forums/index...39543&st=45

Also here is the Rx330 10 page PDF instructions for the hitch and wiring:

http://www.sewellpartsonline.com/import/PDF/RX330_TOW.PDF

RX300 Dash Parts

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I wired up my 2002 RX300 2wd that did not have the towing package. I'm including a diagram of the connector and explanation as I didn't find others that were specific and had to figure it out from multiple sources and my own test light.

1. there is a white multi-pin connector at the 10 o’clock position of the spare tire. Remove the spare and you should have plenty of access. See the attached diagram for the pin-out. Note that the +12vdc pin is hot when the fuse is installed. Leave the fuse out while wiring things up.

There are a couple of threaded studs studs near the connector, one of which will make a nice ground connector point.

2. I got a universal Trailer Light Power Module from my local U-Haul dealer and was shocked that it was the best price of any I'd seen online, just $40. Part 13493.

3. The power module had 6-wires out the vehicle end. One was a ground and it had a connector on it for the stud. Of the wires the 12vdc wire was the shortest at about 9 inches so I cut all the others (except the ground) to match. Removed 3/8” insulation from each wire and tined them with solder then flattened each end with the pliers. The power module had double sticky tape on the back and I stuck it to the surface at the 9 o’clock tire position. I slipped the 5 tinned wires into the connector as labeled. Tested the output with a load (hooked it up to the trailer, and put the fuse in) . It all worked so I used some silicone (RTV) glue on the wires that stuck into the connector so they would not come loose and glued the connector down to the metal as well. Job done.

Note: The power module uses the +12vdc line to power the trailer lights. Each of the other wires going to the vehicle connector are simply sensor wires that draw only a miniscule amount of current. This way the vehicle does not detect any additional drain on any of the light circuits and no fault lights are thrown.

Lastly the U-Haul connector includes green LED test lights that indicate power for the various circuits. I used these when initially testing and when they worked right I went ahead and connected the trailer. The power module kit included zip ties and extra wire etc that were not needed though I did tidy up with the zip ties. I figured out the connector using a standard test light.

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Thanks Bob Q

I did it just as you described.  Part #13493 is no longer available.  Part #14494 is what I used.  Works great. 

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OK, so I know this topic is old (like me & my car), but is there any chance anyone knows the part number or where I can get the 10 pin male plug that would fit into the Trailer harness socket, sure I could tin wire (if my hands didn't shake much - alcohol or age?) but I'd prefer to get a plug and wire it up and then plug it in. Before anyone says "Google it" I have for about 3 hours last night and I had nightmares of drowning in electrical sockets. Great site, grovel, grovel. Hey, question, if the brake light warning is on but they both work, is it the brake light on the window? - that doesn't seem to come on when I put a 10lb barbell on it.

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