Trailer Hitch Installation

C

Christopher-Robyn

New member
I'm not sure this is the appropriate forum, but I need some help. I thought I was done with the installation of an OEM tow hitch on my wife's 2004 Lexus 330RX, but when I tested for voltage at the rear 4-pin connector, I got nothing. The dealer says since the vehicle did not come with a tow prep package, I need to install a new type electrical junction block assembly. I ordered one, but I have no idea where the original one is located, or what it takes to replace it. Any advice will be greatly appreciated. Thanks!
Paul K
 
Christopher-Robyn":392hrlpp said:
I'm not sure this is the appropriate forum, but I need some help. I thought I was done with the installation of an OEM tow hitch on my wife's 2004 Lexus 330RX, but when I tested for voltage at the rear 4-pin connector, I got nothing. The dealer says since the vehicle did not come with a tow prep package, I need to install a new type electrical junction block assembly. I ordered one, but I have no idea where the original one is located, or what it takes to replace it. Any advice will be greatly appreciated. Thanks!
Paul K
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I would go to U-Haul and have them install a wiring harness. They splice into your existing wires and it takes about 15 minutes.
 
Capt. Matt:
The dealer (Lexus of Roseville, CA) that I ordered the junction block from told me that the new block replaces the old one & has new circuitry required to provide for the trailer lights. Supposedly it just unplugs, but I'm not sure where to find it. They weren't sure. If push comes to shove, when the new part arrives, I'll see if U-Haul or a Lexus/Toyota service department mechanic will show me where it goes. I still have the entire rear cargo area dismantled in order to connect the trailer hitch wiring to the vehicle connector. Thanks!
Paul K
 
I agree on the U-Haul thing. I took my Pilot there, unfortunately the day I went only 1 person working so took about 3 hours, he charged me $35. By the way if that trailer has brakes you need a 5 pin flat, not the 4 pin. That 5th pin is the trailer brakes and is hooked up to your cars back up lights.
 
Ken:
I hope the part comes with instructions like you've shown, but according to the dealer, I don't think it will. The vehicle arrangement looks different from mine, but it's a great help. I bet the connect-up is the same. Hopefully when the part arrives, by comparison, I'll be able to locate the old one. I really appreciate all the help!
Paul K.
 
Although I cannot speak for the specific Lexus model, many vehicles have a separate fuse sysem for the trailer lights. It is very possible that the fuse was not installed if there was no hitch in place.

The 5th pin is to lock out the brakes when you back up (selenoid interupts the bake line, so no pressure from the surge brake cylinder to wheel cylinders). It is not necessary, because you can put a pin through the trailer tongue behind the surge hitch, or a C clamp, or Chain vise grips to keep the surge brakes from activating when backing--just be sure that they work when going forward.
 
Bob:
Thanks. That was one of the things I checked when I had no readings at the connector. There is a 30 amp fuse installed for the tow hitch circuit. It was there & was good.
Paul K
 
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