Towing With The Rx400h

[chemistken]

My 2007 RX400H has a trailer package (installed by Lexus) which includes a 4 wire electrical connector. The manual states that this car can tow up to 3500pounds. I bought an RV that weighs 2500 pounds and has brakes. I contacted several Lexus dealers along with numerous RV dealers. ALL of them refuse to modify the electrical connector to a 7 pin round connector which is necessary to activate the RV's brakes. Lexus now tells me that if I get it done it will harm the hybrid computer and charging system. By the way I even went to a Toyota dealer (Highlander hybrid) and they said the same thing. I feel very mislead by Lexus.

Any ideas would be appreciated.

Ken

[retired00]

My 2007 RX400H has a trailer package (installed by Lexus) which includes a 4 wire electrical connector. The manual states that this car can tow up to 3500pounds. I bought an RV that weighs 2500 pounds and has brakes. I contacted several Lexus dealers along with numerous RV dealers. ALL of them refuse to modify the electrical connector to a 7 pin round connector which is necessary to activate the RV's brakes. Lexus now tells me that if I get it done it will harm the hybrid computer and charging system. By the way I even went to a Toyota dealer (Highlander hybrid) and they said the same thing. I feel very mislead by Lexus.

Any ideas would be appreciated.

Ken

The '06 manual actually says trailer brakes are required for 1000+ lbs. It would seem there is some misunderstanding here--just take the manual pages in and go from there.

[mrc88dal]

Can't you just use an adapter plug to change the existing connection to 7pin? I use one on my trailer(4-pin)-to-Tundra(7-pin receiver) connection but my trailer doesn't have independent brakes so perhaps that wouldn't work. If it will work, you can find them at auto parts stores etc.

[Gryphon]

An aftermarket supplier of towing parts would probably do it for you. UHaul for example.

Tom

[skyfish400h]

My 2007 RX400H has a trailer package (installed by Lexus) which includes a 4 wire electrical connector. The manual states that this car can tow up to 3500pounds. I bought an RV that weighs 2500 pounds and has brakes. I contacted several Lexus dealers along with numerous RV dealers. ALL of them refuse to modify the electrical connector to a 7 pin round connector which is necessary to activate the RV's brakes. Lexus now tells me that if I get it done it will harm the hybrid computer and charging system. By the way I even went to a Toyota dealer (Highlander hybrid) and they said the same thing. I feel very mislead by Lexus.

Any ideas would be appreciated.

Ken

The power required to operate the brakes may be too heavy a drain on the 400h electical system. Does the trailer have it's onw power supply for the brakes or does it drain the from trailer connection?

My guess is that connectors are different for just this reason. The "round" connector probably has a dedicated 12V hot lead that is used to power the trailer brakes. Where the "rectangular" connector is only designed to power another set of turn signals and brake lights (4 leads: right, left, brake, ground). The "5th" lead would be just a 12V constant power lead. That is the lead that may be too much for the 400h.

To run a dedicated power lead from the main 12V bus to the hitch area should be something a trailer shop could do, but I would avoid UHaul at all cost. Maybe their install business is OK but their rental business has been run into the ground by greedy corporate executives. Sad to see yet another American icon go the way of Sears&Robuck.

[wwest]

My 2007 RX400H has a trailer package (installed by Lexus) which includes a 4 wire electrical connector. The manual states that this car can tow up to 3500pounds. I bought an RV that weighs 2500 pounds and has brakes. I contacted several Lexus dealers along with numerous RV dealers. ALL of them refuse to modify the electrical connector to a 7 pin round connector which is necessary to activate the RV's brakes. Lexus now tells me that if I get it done it will harm the hybrid computer and charging system. By the way I even went to a Toyota dealer (Highlander hybrid) and they said the same thing. I feel very mislead by Lexus.

Any ideas would be appreciated.

Ken

Four wire connector..

Ground

Parking/street/tail lights

Left brake/turn signal

Right brake/turn signal.

Mount a small 12 volt lawn tractor battery on the trailer tongue and use a 12 volt relay to energize the brakes. Energize the relay via a wire tapped/spliced into ANY brake light circuit. If the battery voltage needs to be maintained, long distance trip, run a wire to the rear cigarette lighter output.

"..will harm the hybrid computer and charging system.."

There is some truth, potentially, to that statement.

Your trailer brakes are electro-magnetically operated and that could, would most likely, result in a HUGE electrical spike upon each release of those brakes. So any "direct" electrical connection between the trailer braking system and the towing vehicle's 12 volt power could potentially damage any electrical components sensitive to those over-voltage spikes.

[Dr K]

My 2007 RX400H has a trailer package (installed by Lexus) which includes a 4 wire electrical connector. The manual states that this car can tow up to 3500pounds. I bought an RV that weighs 2500 pounds and has brakes. I contacted several Lexus dealers along with numerous RV dealers. ALL of them refuse to modify the electrical connector to a 7 pin round connector which is necessary to activate the RV's brakes. Lexus now tells me that if I get it done it will harm the hybrid computer and charging system. By the way I even went to a Toyota dealer (Highlander hybrid) and they said the same thing. I feel very mislead by Lexus.

Any ideas would be appreciated.

Ken