6.0PSD

Been wanting to find out what was causing trailer lights not working and went searching for the converter box to test all wires going in and out...

This is a factory installed hitch/light converter tow package on my 1999 AWD rx300

This shows the 4 pin harness wire loom going from converter box down through that hole under the spare tire which then runs direct to the receiver end with the 4 pin harness which is bolted to receiver


Closer look at box and wires...


Box has 6 pins going in...



But, harness only feeds it 4... Guessing one of the extra pins on box should have been a 12v feed...



The 4 pin output side harness...
To better show location... The factory converter in my 99 is installed all the way back against wall just about under the left rear light... Hope pics show location best... It was just double sided taped in that location...

6.0PSD

So after testing the feeds Box was not sending out right turn signal or right brake... I'm not sure if left turn is failing or if it is normal but voltage was sporadic but left brake was solid battery voltage...

My 4 pin harness plug @ receiver is missing the ground post but all the wires there tested the same as the 4 pins directly on box so I will be adapting a new plug there and just splice it at receiver using weatherproof couplers...

Now I just need to figure out what to do with the converter... I plan on popping it open to explore but don't expect to figure out what failed, should one of the 6 pins have direct 12v? What do the newer factory installed converters use to feed, is it also a 6 pin/but 4wires only going in?

I can always find a modulite to tap in there instead but need to find the right one... Anyone know if the Modulite 119146 will work? My little 4x6 trailer has leds so there isn't much draw.

cotis

I have the same car and had a similar problem with my factory unit. I think I burned it out when I rented some equipment and the POS trailer it was on had really messed up wiring. It shorted out my unit and burned it up. I replaced it with a universal unit like you mentioned (mine was Hopkins brand), grabbing 12V power from the cigarette receptacle on the left side of the trunk since it is a large, dedicated 12V source with its own fuse (more than enough to run a trailer). On the factory unit there is not a dedicated 12V input (this answers your question, NO - none of the 6 wires coming in is +12v).

The converter combines the tail light/turn signal functions since they are separate on the RX300. It also isolates the trailer from the car so any problems don't migrate back to the vehicle. Unfortunately it is not serviceable. The entire thing is epoxy potted and impossible to disassemble without complete destruction. Easier just to replace with a universal unit like you mentioned.

The input wires map directly to the stop/left turn/right turn/running light wires, just use a meter or test probe to figure out what is what.

6.0PSD

Soon after I posted I started cutting into it to find just that, it is a solid piece of rubber/epoxy...

I'm guessing that any 3 wire system converter will do, just a matter of how many lights your trailer has so it would need more amps for more trailer lights. Truth is this oem converter is rated at 15amps and still failed but think that with the 12v feed it will hold up a lot better...Not sure how many amps two little amber clearance leds and the two rear led lights draw but shouldn't be much so I'm guessing the converter I mentioned above should be sufficient. Mine was already bad when I purchased my car

How has yours been holding up connected to the outlet?

BTW, I had tested the 6 pin harness which only has 4 wires and know there is no 12v there... I was asking to see if any of the other two extra pins on the box itself should have had 12v, wondering what they are for since they are part of the converter but just not connected to anything...

6.0PSD

Decided to order the CURT 56146 converter, "MADE IN USA"

Hope to get it by next weekend...

After looking through the installation wires for the CURT I ordered, I would now think the oem should have had a ground and a 12v feed which would make sense since there are two unused pins... Wonder if it was accidentally forgotten on every factory installed setup or they were too lazy to properly finish the install which caused all the failed converters...