Living where I do, one often has use for a trailer hitch to tow a trailer or caravan. Limited luggage space and long distances often means having to move furniture and such. Many places offer free loan of a trailer to get your shopping home.

After searching about eBay and other sources I decided to buy a brand new trailer hitch kit from Rameder in Germany. I don't live in Germany, but within the EU so they offered to ship it to me. Their service is above and beyond so I really do recommend them if you live within the EU. You could pick up a used hitch on eBay for less money, but putting a few euros extra into the game you get a brand new with all the fittings needed. I found this worth the extra money.

Please also see the E32-specific article about trailer hitches.

The trailer hitch can be ordered with or without the electrical wiring kit. I want the original BMW wiring and modules to get check control functions on the trailer bulb as well. But for now I'm going to use the aftermarket kit which supports CC systems. Though you do NOT get the instrument cluster warning you get a buzzer that lets you know if a bulb is out. Also I ordered the complete kit to get brand new wiring to the hitch, which I'll adapt to use with the original BMW trailer modules when I find them on eBay.

The kits consists of the following items:

• Trailer hitch bar
• The hitch / ball
• Trailer electrical connector mounting plate
• 2 bars for reinforcement
• All bolts and nuts needed

The electrical kit consists of:

• Wire harness
• Trailer module
• Buzzer module
• Trailer electrical connector

If you have check control you will also need the CC kit which consists of a module and a single power wire. This module hooks into the above standard kit. 

The wiring kit is of good quality which is made to fit nicely into the vehicle. The kit  just plugs into the various connectors of the existing wiring in your vehicle. All wires are in rubber tubing and comes with a trunk floor pass-through rubber booth as well. Trailer electrical connector ends come with reinforcements too. You will only need to hook up extra power from your battery, and provide a good grounding point.

Overall the kit is very good. I believe this is the same kit you actually did get on your vehicle when new. Except for the wiring kit that is. All is made by Oris.

Mounting

Takes about 2-3 hours to complete depending on working conditions and tools available.

Note! This is a job for two persons!

Remove rear bumper by carefully prying out the strip on the backside of the bumper. Start at one end and pull it gently off its clips.

Now you'll either have revealed four 17mm nuts that hold the bumper onto the vehicle. Unbolt these.

Before pulling the bumper work on the rear inner wheel arch protections. These will need to be carefully pried out so that they rest on the outside of the bumper instead of inside the bumper. Otherwise you'll have problems removing the bumper. These can be tricky as they're of hard plastic.

Do NOT forcefully pull out on the bumper sides as you will break the bumper mountings.

When the inner wheel arch protections are freed from the bumper, pull the bumper backwards. Here's where you want to be two persons so that you can pull straight without damaging the bumper mountings. Note the bumper is heavy! Please take care to retain the gasket around the entire top of the bumper.

Place bumper in a safe place.

The trailer bar mounts using 6 hex bolts into the frame of the vehicle. The holes are already present but they may be filled with dirt and grime. Working under the car clean the two holes on each side of the vehicle, plus the two near the center of the vehicle. There seems to be some kind of glue/protection always near one of two of the holes near the exhaust so you will need to carefully clean this away so that the bolts will fit. Make sure the bolts will fit nicely before you attach the trailer bar to the vehicle. This will save you a lot of work!

Place the trailer bar (two persons again) to the car. You can let it rest carefully on the exhaust while you mount the right side bolts. This might be a very tight fit and you may have to rotate the bumper receivers so that you can slide the bar in place between them and the chassis. If you can please do remove these receivers. Mine were very rusty so I could not loosen the hex bolts that mount them. If you can remove them the job will be many times easier.

I found that getting the right side in first was easiest because I had a little bit more room on the left side. It's also a tight fit to get the reinforcement mountings in the correct place. I had to use some foot power to kick it in place. 

Mount all the bolts and let them be finger loose as you will need to adjust the bar when you start with the left side bolts. When all bolts are in place, tighten up to the correct force.

The above pictures are examples from my E32, but the bolts are in approx the same place. Follow the instructions that came with the trailer bar.

Remove the trunk carpets and trunk plastic cover around the trunk lock.

Remove the right trunk floor plug right to the spare wheel. Feed the wire kit into this hole until you can pry it out the center hole above the trailer bar. Mount the rubber booth properly.

Connect the trailer electrical connector to the wires. I had some issues with the cable being a bit too short to reach the left tail light assembly. About 10-15cm more would have done. The right side harness seemed too long as well, so I think this kit was designed for a new drilled hole in the center of the trunk floor instead of using the factory holes. However I did get it to work through the rightmost factory trunk floor hole. Just!

You will now need to drill 4 holes from rear of the car into the trunk for the reinforcement bars. This is an easy task when the trailer bar is in place as you can drill the 8mm holes through the mounting holes. Remove any metal debris and apply anti-corrision paste to the holes. Bolt the reinforcements in place.

You will now need to cut an opening in your rear bumper so that the trailer hitch can protrude. The opening need to be at least 8 cm wide (3 inches). It should be dead center.

When looking at the bumpers inside (place it upside down while performing these steps), you will see a tab sticking up on the lower part of the bumper. This is dead center. Drill four 8mm holes in the bumper near the lower and upper sections around the center area. Cut out the section. There's no need to open up all the way down the bumper like on the E32!

< will provide picture here later to illustrate better >

Note! Please make sure you have the trailer electrical connector is wired up at this point, and connected to the bracket. The bracket and hitch must NOT be mounted onto the trailer bar yet.

Place the bumper back on the car. Make sure you slide it into the side tracks on both sides and that the gasket is in place. Replace it as needed. Applying some grease to side tracks may help. Also make sure you get the trailer electrical connector through the opening before you slide the bumper fully in place. Before you bolt the bumper in place bolt on the trailer hitch and electrical connector bracket.

Bolt bumper in place and replace the plastic strip.

This kit only requires one good ground point and one or two wires to be run to the battery. No cutting or splicing should be required. However, if you do I strongly suggest soldering connections together to make the durable. 

Only one wire strand goes to the right side light assembly. The rest should be routed to the left side. Exception for the two power lines that need to be hooked up to the battery via two fuses (Note! Only one if you do not have check control for lamps). These power lines are at least 3 ft too long so you have plenty of space to route them wherever you feel like. I routed them behind the trunk jamb cover where all the other wiring is as well.

It's a real no-brainer, though some wire colors are mislabeled in the instructions. One goes to the right light assembly, the other just about to the left light assembly (marked R and L), the third harness is routed up to the trunk lid where it hooks into the left and right foglight connectors. Route the wire at the left side of your vehicle. Due to a bit short wiring here, I only stripped it down near the trunk lid itself and let the wire run down and behind the left trunk cover.

The buzzer that comes with the check control kit is hooked into the two left over spade connectors. I cut the 4-pin vehicle connectors brown wire that is unused near the left tail light assembly. I then fitted a ring shoe and bolted this and the ring shoe grounding connector together. The CC module was inserted into the 10-pin connector after the jumper connector was removed from the harness. Both modules were bolted togehter and tucked nicely under the left tail light assembly.

After hooking up the powerlines to the battery via the provided nice 15A fuseholders I checked that the connector worked properly using a multimeter.