Fitting Tow bar to IS200


How to fit tow bar to IS200.


I have been kicking around this site for a while now and I thought it was about time I actually posted something.

Here is my guide on how to fit a tow bar to an IS200.

Hopefully, everything in this guide is correct, if you see something wrong please tell me.

I removed all the boot linings so that I could clean the car out and have a good look around.


I took the next few pic’s to show the various wiring connectors and the two drainage tubes coming down from the sunroof. You can also see the alarm siren and remote opening ECU tucked up in the "C" pillars.









You can also see some surface rust appearing deep in the inside of the rear arches. This is due to water ingress that I think gets in through the rectangular shaped vents. I expect this happens while driving through deep puddles and jet washing. You can't seal these up, they are needed for air circulation. I will be rust proofing the area later.





Make sure you have everything available, bolts, nuts, washers etc. especially if like me you brought a second hand part. This cost me £30 from Ebay - yes you can still get bargains off there.



I have wire brushed and painted it, you cant put dirty things onto a car.

The next pic shows the rear tow bracket and under tray. Both need to be removed before trying to fit the towbar. The under tray is attached buy four rusty nuts so use some penetrating spray and the Tow bracket is attached by three bolts. Keep one bolt handy because you need to refit it to the car.





The rear silencer needs to be dropped. I pulled the rubbers from the back box but I think you can unbolt the complete rear hanger, be careful because rust will have got to these as well.



Don't forget to support the silencer. I didn't jack up the car so I just used a couple of bricks and jack to take the weight and dropped it lower when I needed to. I didn't want to leave it at an awkward angle any more than necessary and have to deal with a split pipe.



I also put some tape over the bumper to help avoid and scratches.

These pic’s show the rust developing, remember this car is getting on for 12 years old so I expected a bit. I cleaned this up and treated it. If you look at the rear sub frame mountings there is some light surface rust appearing. This could develop into an expensive MOT failure in later years.











I also took a pic of the car looking from the back to the front so you can all see and compare. If I find myself with some spare time this year I might rust proof the underneath.



The exhaust heat shield needs to be removed. You can see that two of the bolts snapped when I tried to remove them. You could try soaking the bolts in a penetrating fluid for longer but if you see the large holes in the heat shield I think you will have trouble, keep an eye out for my 'repair' in later pic’s.





Underneath the heat shield you can see there is less rust. You can also see two blanking bolts. These need to be removed.


Trial fit the tow bar to check that it is straight and fits nicely. Four of the six holes are pre drilled and threaded for you. The remaining two should be marked (using the tow bar as a guide)







If you look carefully in the pictures you can see dimples in the chassis rails. These are guides to show you where to drill. They are more obvious from the top than the bottom. The one on the nearside was difficult to find, I had to take off some paint and rust proofing to locate it.

Measure, check and measure then do it again to make sure. You will be drilling into the chassis rails. This will affect the structural integrity of the car so it never hurts to take your time over this.

You can drill a pilot hole from the top and then the bottom using the dimples as a guide rather than using a long bit and drilling two holes at once.





If you are confident then you can use a long drill bit and drill right through

I used a long 5mm drill bit to drill a pilot hole and drilled from the top down. Make sure the drill is square to the chassis rails otherwise you will come out in the wrong place.

Check to see if you are in the correct place by offering the towbar up to the car. Once you are happy the pilot holes are central to the towbar bolt holes use a hole cutter to enlarge them so that they can accept the tubes from the bolts.



The upper and lower holes have to line up. I drilled from the top through.



You will also have to drill a hole so that the cable can enter the body and connect to the lights. I drilled this by the jack housing.

Check that everything fits. Then rust proof. Pay particular attention to any bare metal. I used Kurust rust killer and then some galvanized spray paint. The spray is great for underneath the car, I used it in the front arches when I replaced all the suspension last year. Don’t forget to paint the inside of the chassis rails too.









Fit the towbar and run the cable into the car using a rubber grommet to seal the hole and secure the cable. I think that with some towbars you have to cut the bumper a little. It was tight on mine with the lower lip of the bumper rubbing on the electrical socket plate.





I used some copper slip grease on all bolts and threads. I have a big pot of this so I use it on everything. It helps to keep everything from rusting.

Tighten everything to the specified torque.

Both the under tray and the exhaust heat shield need to be cut to fit back on the car.







Refit the exhaust, I removed and cleaned up the exhaust hanger while I had easier access. This is the original exhaust so I expect I will have to replace it in the near future.



Now you have to connect the wiring. Because the IS has a bus system with bulb failure warning system you cannot just connect to the rear lights as with older cars, you need a bypass relay. This device takes a signal from the light wiring and draws power for the trailer from a source more suitable.

I couldn’t find a permanent or switched live in the boot suitable for the amount of current that I could be pulling in the so I ran a live from the battery. This MUST be fused.

You also need an earth. I stayed away from the earths already used, this car has far too many ECU’s for my liking so the less I disturb them the better.

Place the Bypass relay somewhere easy to access, away from the possibility of water or mechanical damage. I found the ideal place but then realized that it was in the way of the jack!!

If you are planning on towing a caravan you will need to run extra cabling.

The picture below shows the wiring connections. A lot of people don’t like the blue connectors but the alternative is to strip the insulation and solder, it's up to you.



Keep it as neat as you can and tape up the loom when you have finished.

Check everything is secure and then replace all the boot trim.

That’s it.

You have to bear in mind any license restrictions when towing especially for you youngsters. You should also be aware of the vehicle, tow bar and trailer limitations.

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Hi captain,

No comments on your how-to (just one word: perfect), but I would like to add that in case of an automatic transmission, an additional oil cooler is mandatory (for extra cooling of the transmission oil) according Lexus. This special note was also mentioned in the manual of the Thule towing bar I mounted on mine (and seems to be a fairly normal 'thing' for cars with auto trans, applicable for most makes and models actually, but not everyone seems to know this (including me)).

For bringing some garbage to the end of town won't be a problem, but towing heavy loads in the mountains will eat up the standard cooler capacity for sure. After installing the second cooler (mounted in line and after the original one) I was amazed how much the oil is being cooled by the 2nd cooler.

Just to avoid problems for the automatic fellas, hope it ads something here...

Keep up the good work,


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Hi I'm fitting a towbar to my Lexus can you help me, do know which wire connects to what from the car to the relay really scratching my head

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