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451 Retrofit Power Steering

Modification Details

This guide is for a right hand drive UK car. LHD cars will probably be the mirror opposite.
For future reference, PAS = Power Assisted Steering.

Fitting The Power Steering Controller

This is the power steering controller for the fortwo 451. Smart part number:
A451 545 09 32 (version 1)
A451 545 62 32 (version 2)
A451 900 32 00 (version 3)

All 3 versions will work.

It has 3 separate connectors. Data, power in and power out to the power steering motor.

If you remove the side part of the dash on the same side as the SAM unit (fuse box), you should see the
connectors there already. I have yet to find a 451 that doesn't already have the wiring in place already.

You are looking for a large multi-pin white connector. A black 2 pin connector and a blue 2 pin connector.
Also you are looking for the ring connector (earth). Ignore the multi-pin yellow connector.

The PAS controller bolts to the front bulkheadin the position shown below (RHD).

Take a close look at the bulkhead and you'll see 2 threaded stud that the controller can mount to.

Before mounting the controller, slide the ring terminal over the top stud.

Then slide the controller over both studs making sure that the ring terminal is secure on the stud.

You will need 2x M6 locking nuts and 2x M6 washers.

Place the washers and the nuts onto the stud and tighten the controller into place. Plug in the 3 connectors.

Fitting The Power Steering Rack

Brace the steering wheel so it can't turn.

Jack the car up at the front, remove the wheels and disconnect the steering rack arms.

To stop the ball joint from spinning you hold it with a Torx bit whilst undoing the 17mm nut

Then use a ball joint splitter to free the compression fitting.

The crossmember is bolted in with 4 bolts. The crossmember holds the steering rack and the wishbones.

Brace the middle of the crossmember with a jack so it doesn't fall when you remove the bolts.

When all 4 of the bolts are removed, lower the jack slightly to lower the crossmember a touch.
You need just enough room to be able to reach in and undo the 13mm univeral joint nut.

Once you remove the nut, you can pull the bolt out the other side and flip the end of the steering column out
of the way. The bolt you have just removed is an off centre (or cam) bolt which locks itself as it spins.

You can now let the jack down further and the middle of the crossmember will drop down.
The ends of the wishbones will still be held up with the suspension. It makes it easier to refit the crossmember.

In these pictures however, I was doing other jobs so I disconnected the suspension as well.

You should now be able to lower the crossmember enough to reach the 2x 15mm bolts holding the rack in.

Remove these and fit the PAS rack and refit the bolts you just removed.

Look up above the crossmember to locate the 3x wiring connectors.
1x black, 1x grey, 1x white. These all plug into the new PAS rack.

The single white connector plugs into an earthing tab by the motor. The other 2 connectors are obvious.

Jack the crossmember back up, refit and tighten the steering column onto the steering rack shaft,
refit the 4x crossmember bolts, refit the steering rack ends into the hubs and tighten it all down.

Refit the wheels and then place a 30 Amp fuse into position 35 on the SAM unit.

Programming The PAS

If you just plug it all in and go for a drive you will notice 2 things.

Firstly, the power steering works. Secondly, There are 3 error lights showing on the speedo.

The error lights are because the car isn't expecting the data it is receiving from the PAS controller.
So, the car has a little spaz out, throws up error codes and disables all of the traction control features.

Thanks for that smart, you arseholes couldn't have made it just work no?

Anyway, I went to my local smart dealer and asked about having the car coded for PAS.
They looked on their computer, it wasn't on there so they refused to do it.
My option was that they would take the car and look into it but it could cost a load.

I was contacted my Bryan P who had just paid smart to retrofit the PAS to his car. It worked with no error
lights so it is possible. I asked which smart dealer managed to complete this task and I contacted this
smart dealer at Bishop's Stortford and made contact with their main smart specialist George G.

He stated that it was a simple task of updating the vehicle data card which then allows the correct
coding of the unit using Xentry. Once this is done, the PAS will work with no error lights on the dash.

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