Power steering problem.

[pistanbroke]

Hi, I am a Newbie to this site, having just bought a low mileage 2003 Pulse Coupe for my eldest daughter. The car only has 39000 miles on the clock and runs great but there appears to be a problem with the steering.
Unusually (or so I`m told) this car does have the electric power steering fitted, of this I am certain as I can see the electric motor attached to the steering rack and it has the control module next to the battery.
When stationary, or at very low parking speeds, the power steering works well and the wheel can be turned almost with one finger, but as soon as the speed goes above about walking pace the power steering seems to switch off and the steering becomes very heavy with no self centering at all. So heavy in fact that on the 60 mile drive home it made my arms ache.
I have read that bottom ball joints can seize, so jacked up the car and disconnected the steering arms, and both bottom joints are free, as are the track rod ends.
I also read that the universal joints in the column can seize, so checked these too and both are OK.
The car had a new battery fitted recently during which the radio code was lost, can the same thing happen to the power steering control module?.
Has anyone else encountered a similar problem and know of a cure?.
Will I have to replace the steering module, and does it need to be re-coded by a smart dealer?
Thanks in advance,
Ralph

[ossy]

Sorry for my bad English, it is not my first language.

Maybe, this will help. (It works on my smart very well.)

If you look behind the left front wheel, there is the steering column

When you look closer, you see the steering rod, thats goes up.

There is a rubber seal, carefully remove the rubber seal.

Put some oil in (ATF or similar) it.

Replace the rubber seal, and go for a test drive.

If it does not resolve the problem, then it may be the ball joints.

[137699]

The power steering only works at low speeds, so the switch off is fairly normal though I believe it should switch off at about 20-30mph - I am not certain of this.

The lack of self-centre is a "characteristic" of power steering on the 450. Ours is exactly the same and I have heard of others say they have it also.

However the steering should not be so heavy it makes your arms ache - if that is the case then, as Ossy suggests, you have possibly an issue with ball joints, track rod ends, suspension bushes/top-mounts etc.

[ossy]

On a smart tour (with other smart-drivers of the Dutch smartforum), i hit a speed bump, very hard.
Than mine steering wheel wont turn it self back, when you came out of a corner.
I had to turn the steering wheel with both hands.
The next day, i put the oil in it.
The problem went away.
This is now , 4 months ago.
Still no problems

[tolsen]

I suggest you jack up the front and check out steering by turning from lock to lock. That is the only sensible way to identify stiff steering issues.

[pistanbroke]

Thanks all for your suggestions, but I have already eliminated ball joints, track rod ends etc. When jacked up it is impossible to turn the wheels by hand and even using the steering wheel it is stiff, but when the track rods are disconnected the wheels can be "turned" easily by hand so I know neither the bottom ball joints or the top mounts are seized. The problem must lie in either the rack itself or the control module.
The lack of any self centering , if normal, is in my opinion dangerous, and I cannot believe they would be allowed to make them this way. On the journey home I nearly ran into the kerb on exiting a roundabout because I could not wind off the steering lock quick enough. If this turns out to be "normal" then the car will be quickly sold as there is no way I would let my newly qualified daughter loose in the thing.

[tolsen]

You have weak arms? Perhaps you should do more exercise.

[Thrumbleux]

Thanks all for your suggestions, but I have already eliminated ball joints, track rod ends etc. When jacked up it is impossible to turn the wheels by hand and even using the steering wheel it is stiff, but when the track rods are disconnected the wheels can be "turned" easily by hand so I know neither the bottom ball joints or the top mounts are seized.

Possibly you are having to fight the electric motor with the gearing in its favour.

The problem must lie in either the rack itself or the control module.
.

Add you location to your profile (to show with your avatar) and perhaps someone in the vicinity can check out the coding aspect for you. If the rack is goosed it might (electronics permitting) be possible to convert to manual steering which works very well and centres as steering should.

[tolsen]

Something is not right for sure. Steering wheel should turn freely with the little finger when front is jacked up. Stiff joints will upset the controls. Stiff universal joints is most likely and should be easy to diagnose whilst jacked up. Typically there will be hard spots when turning steering wheel. Also inspect steering rack gaitors and gaitor clips. Look for splits, cracks and holes. Renew rusty clips.

[pistanbroke]

Possibly you are having to fight the electric motor with the gearing in its favour.

To be honest thats what it feels like. As if the power steering has failed. Feels perfectly normal and how I would expect it to feel when stationary, but on the move it is the same as stationary with the engine switched off, ie no assistance whatsoever.

[tolsen]

When jacked up, is there any difference whether engine is running or ignition off?

[pistanbroke]

Absolutely, light as a feather when jacked up with engine running, stiff when engine turned off, which is what you would expect really.

[mccsmart2002]

I have electronic power steering on my 2005 fortwo. I have had the issue over the years with the universal joints partially seizing (causing stiff steering) but that applies to any 450 fortwo, with or without EPS. Resolved with an application of chain lubricant, GT85 or similar.

I don't have issues with mine not self centering. The only issue I do have is an intermittent problem with the EPS itself. When it is playing up, you sometimes get no assitance at all, no assistance but heavier steering at low speeds, normal steering with assistance at low speeds. Sometimes the steering wheel will turn all the way or part way to the left on its own when coming to a stop (i.e. walking pace). You can stop this by simply holding this steering wheel. It sounds worse than it actualy is. Siwtching off the engine and reastarting sometimes clears the fault, but only temporarily.

If you have the same issue, a diagnostic check with MB Star will bring up the fault codes:

N68 Steering assist control module
C1003 Difference in measured values between sensors is too high.

The control module (mounted next to the battery) is not the problem in my case. It is the torque sensor on the rack which cannot be purchase seperately. Last time I checked, a new EPS rack with VAT was around £1,000 for the part alone.

[pistanbroke]

Realised today that neither the ESP or ABS lights were working. A check revealed that someone had removed the bulbs. Of course they are now on permanantly. The car never went into limp mode though which I would have expected.
Had the front off and doused the bottom universal joint with lubricant, we will see if that alleviates the problem with the stiff steering. Still can`t understand why it switches off at 5mph though.

If thats the cost of a new EPS rack I will be putting on a normal un-assisted item.

[tolsen]

Whoever did that deserves to be stoned!