sktn77a

iTrader: (2)

The towing harness converter box on my 1999 RX300 has given up the ghost. It's a black Toyota box (4"x2"x.75") in the left rear trunk bottom with some nondescript name on it - no part number. The lexus dealer and toyota dealer can't find the box alone, just the complete (unnecessary) wiring harnes from the towing package.

Anybody had a similar problem and fixed with the OEM patr or a plug-in equivalent (no cutting stock harnesses)?

Thanks

bob2200

I haven't had this problem, but it seems to me that you ought to try a Lexus auto recycler (i.e., junk yard) for the part. If there isn't one nearby, a little looking on eBay will yield several companies parting out Lexus cars.

mikey00

The part number for the converter you need is 08921-00040. It looks like it was never offered as a individual part. It was part of kit 00921-00031 which was replaced by kit 08921-48051. These kits are most likely what the dealer parts guys are finding. They include the wiring, cable ties, manual, etc. You can try places like here for a used one:
http://www.automotix.net/20070405-used-lexus-parts.html

mikey00

Here's another thought. Just buy a Modulite or similiar converter from etrailer or other source and wire it in. When the kit was installed in your car all the difficult work was already done. That being removing the panels and taping into the necessary wires. They are all at the plug that plugs into the converter. Connections are the same. It is just that the Modulite won't have the nice plug in connector.
It looks like the kit from Lexus/Toyota costs about $170. The Modulite is less than $50. The question is how involved do you want to get to save about $120? I would do the Modulite.

salimshah

Sorry to bring up the obvious ..

The box should contain solid state electronics, which are typically robust (after infant mortality curve).

The connector to the trailer is exposed to weather. Have you cleaned it up thoroughly ... make sure there is no corrosion bridge between pins (front and back). A while back another member reported this problem.

I would also check the 12v connection to the acc/cigarette lighter in the back as well as the gnd wire.

Salim

sktn77a

iTrader: (2)

Yes, I did test the box - voltages going in are good and as they should be; coming out on one side are missing. So I'm pretty sure it's the box.

I really don't want to go cutting and splicing wires so I'm prepared to pay somewhat of a premium for the Toyota box. Maybe the Toyota dealer will have it cheaper ()

mikey00

Really not much cheaper at Toyota. It's $161 at toyotapartscheap.com. You really wouldn't have to cut or splice any wires to use the Modulite. Just use snap connectors and leave the existing plug in place. Or you could just go to a trailer place and have them replace the Lexus box with Modulite or whatever brand they use. That should be no more than $100.

sktn77a

iTrader: (2)

Well, I ordered the part as decribed by my own dealer and on this forum (08921-48051). It arrived yesterday but it's totally different from the factory one that's in there right now (has "2000.8~" on the installation instructions, which I take to mean it's for a very late model year 2000)! It's basically a new install. Before I rip the car apart, I want to make sure it will fit. Does the 1999 have a "lamp failure module" under the rear left sidewall in the trunk? It has a plug to attach there and to the rear light cluster on both sides.

Helena

I have a 1999 rx300 with factory trailer hitch and wiring. I found that the trailer lights were not working due to the failure of the OEM box, it was burned up. After much research and effort I replaced the part with the new part and part number 08921-00031 that I got from Sewell Lexus (they give club lexus 10% discount) for $165. The local dealership was completely unhelpful. The new part looked completely different but worked and is working great as of 2 weeks ago, I put it in 2 years ago. The hardest part was reaching way, way up to find the harness connection. This is a simple repair that an owner can do if you have the right information and part. Happy trailering!

sktn77a

iTrader: (2)

So you had to replace the wiring harness at the back as well as just the box? Was the box totally different (heatsink, different connectors)? Also, did you connect it to both rear lamp modules and to another modeule, also (the Lamp failure module) ie 3 in all?

Helena

The new kit came with a new wiring harness and a completely different looking box. You have the right part number, 08921-0031 is the same as part 08921-48051. I did the research and my husband did the install. He had a very hard time finding the last wire to connect. He had to reach way up to his elbow in the drivers side rear wheel well to find it. He was about to give up. When he found that last wire to connect everything came together. It's been 2 years but to the best of his memory he believes there were 3 connections. TSIB#AXC003-00 later replaced by TSIB AX001-02 were helpful but the diagrams aren't the best. The forum has been great at helping me solve many problems with the 99 rx300. I recently repaired my sticking trunk latch with help I found on this forum. I am thankful for this resource.

sktn77a

iTrader: (2)

Thanks Helena. Anybody know wher I can get a copy of these TSBs? WWW.LexusTSB.com appears to be down.

sktn77a

iTrader: (2)

Spent all day Saturday tearing out interior trim panels and basically disassembling the entire rear interior of the car! The installation instructions that came with the replacement box and harness were pretty complete and there really aren't any shortcuts to replacing the box and harness, so leave yourself plenty of time. Interestingly, the new harness has an additional connection that the original one didn't have - a pigtail connection between the car harness and the "Lamp Failure Module" (the part way up under the trim panel, above the wheel well and just under the rear side window, that Helena's husband had a hard time getting to - you have to remove the trim panel surrounding the rear side window to get at it). Not sure what the point of this is but hopefully this, along with the much beefier converter box, will last now. What really frosts my _ss is that this TSB (Feb 2002) was covered under the new car warranty but they never informed anyone. I've used the towing capabilities twice in 9 years so the part didn't fail until the second time I used it - long after the warranty had expired!

As a final note, I asked my friendly dealer (Rudy, at Johnson Lexus in Durham, NC) for a printout of the TSIBs. He gave me them and told me the problem appears to be that the alligator clip ground wire that clips to the hitch ball is a very poor ground and is the primary cause of all the failures. He didn't have a solution and warned me that it could happen again.

U-Haul roulette!!!

salimshah

Mine was discovered dead, [right turn not going through] yesterday when I went to pick up a trailer.

I am now looking for a used one.

I am still scratching my head as to why the module does not draw +12 .. I was convinced that I had tapped into the accessory plug in the back. Turns out that the module taps in to L-turn, R-turn, Brake, park-lights through the input plug and the output plug grabs the gnd and feeds the 4 prong flat.



Salim

salimshah

Update:

I am now almost convinced that the converter box for early '99 was a dumb 3bulb to 2 bulb device. This allows merging the turn signal and brake light onto single bulb [trailer do not have the amber turn signal].

Over time RX may have switched to "powered" module.

Salim