Engine lost power and steering locked during turn

[driver2000]

I have a GL420 CDI (bought new; 20months old, 20k miles; no off-road use; typical mixture of town and dual-carriage way driving). I was driving on a country lane at around 30mph. On reducing speed to about 20 mph and turning on a tight bend the steering suddenly locked and the engine cut-out. I managed to bring the car to a halt. Engaging park, I was easily able to restart the car and drive home normally (about 5 miles).

Has anyone experienced this? What could the cause be?

Fortunately there were no other cars around at the time otherwise there might have been a serious collision. MB accepted that the car should be recovered to the dealership rather than be driven there by me.

I posted this query on the US MB forum and got a number of replies. It is a bit disconcerting that a number of drivers have had similar experiences. I get the impression that the crankshaft sensor recall was for diesels only, yet the problem has occurred on the petrol models. Someone suggested it was an ECU crash. Someone wondered whether I had knocked the ignition key - but it was still in position 2 when the engine cut-out.

The car is still at the dealership. So far they haven't found anything; the ECU has had the latest software upgrades. They've done a road test with diagnostics and haven’t found anything. I put it to them that the crankshaft sensor might still be faulty but their view is that the crankshaft sensor problem not only cuts out the engine but prevents the car from being started. Right now I don’t accept that view as the recall letter makes it clear that you might be able to start the engine.


By the way, apart from this problem I think the GL is a great car. For 7 seat comfort it trounces the Audi Q7, Volvo XC90.

(For your information here are the other issues I have had with the car, some of which I think other owners have mentioned on the US forum.:
1) Intermittent 'oil level too high' warning. Incidence reduced after software upgrade but it still happens sometimes, usually after driving for some time at over 60mph
2) 'top up coolant' warning. Cured after software upgrade
3) Urgent safety recall P117- to replace crankshaft sensor which, MB quote, ‘an electrical discontinuity in the crankshaft sensor could occur under unfavorable circumstances. If this problem occurred, the engine would loose power. It could also be no longer possible to start your vehicle.’. Work completed in December 2008
4) Auto gearbox control unit problem in January 2009. Symptom was the gearbox stuck in D2. Fixed when gear box control unit replaced.)

 

[driver2000]

GL420: Engine lost power and steering locked during turn

Hi

MB did several long distance (20miles) road tests with diagnostics and found nothing wrong. For my peace of mind they replaced the crankshaft sensor (already been replaced because of the recall), although they didn't think that was the problem they did acknowledge that even replacement components could be faulty and that the symptoms were identical to that described in the recall letter from MB.

I've driven the car for the past week including motorway driving. Everything is fine. Interestingly the mpg on the motorway driving has improved to 29mpg (UK) with average driving conditions (speed < 80 mph).

 

[grober]

It could also be no longer possible to start your vehicle. My interpretation of that statement would be that if the crank sensor failed then you would not be able to restart the car immediately--HOWEVER-----after a short time interval when the engine had cooled down you would then again be able to start the car once more--possibly .

The reasoning being the fault is caused by the sensor failing when hot. Once the engine cooled down the sensor might work again---- or not! Mercedes just covering themselves with a conditional rather than an absolute statement of fact. They might have explained it better.

The fact you could restart immediately would tend to indicate the dealer was correct in saying it probably wasn't the sensor itself since that doesn't "fit the profile" However replacing components under a recall notice by other defective units still in the spare parts system isn't unknown either.

 

[smuggler]

I have worked on a ML before with the exact same symptoms you are describing and it was a very simple solution. This may or may not help, but do you have lots of keys/objects on your keyring? I ask this because the I had the car do the same thing, when the steering wheel turned it managed to catch the keys and turn the key in the off position.
This is the only thing I can think off that would cut the engine and apply the steering column lock. I know it sounds silly, and I didn't believe until after a lot of roadtests. Anyway, hope that helps.

 

[driver2000]

Thanks for the last two posts. Re lots of keys, I only have the MB key fob attached to the key. Re operating temp: that's helpful, the engine hadn't warmed up as I had driven less than two miles from cold - but I would agree that the sensor still could have warmed sufficiently.

I'm taking the view that the problem was a one-off and am not going to worry about it.

 

[driver2000]

Unfortunately the problem (engine cut out leading to loss of power steering and reduced braking) has reoccurred.

This time my wife was driving. The engine cut out on a bend and she was unable to turn the steering wheel sufficiently. There was oncoming traffic who fortunately reacted in time and we all narrowly avoided a head-on collision. Of course without engine power the brakes are not as effective. We were then able to restart the car and drive as if nothing had happened to the engine.

The car is back into the dealership, who have carried out a test drive and run diagnostic checks. Given that I have driven around 2000 miles without any issues since the last problem I wasn't surprised when their test drive didn't reveal anything. And as last time the diagnostic checks didn't reveal anything either (so far).


Also, since the last time we had another problem with the auto gearbox (a message appeared saying to go directly to the garage). This was eventually traced to a faulty battery. It turns out that the car has two batteries, and the second battery was showing quite a low voltage. This may or may not have had a bearing on the engine cut out problem. They replaced the battery.

The issue happening once can but put down to chance, possibly. But twice then I'm afraid I'm beginning to conclude that there could be a very serious potentially lethal defect with the car. Not surprisingly we don't want to drive the car until the problem is resolved.

The car is at the dealership and I will keep you all posted.

(By the way, Mobilo is of no use in these circumstances: they made it clear that if they find that the car can be restarted and driven when they arrive to recover the vehicle then you pay for the call out, and full costs of the recovery if you want it recovered. Last time I had to argue with them to get the car recovered and they accepted eventually but only because they accepted that the brakes could be faulty. This time I didn't bother and drove carefully to the dealer. Sadly this service is not as good as I have come to expect from other manufactures.)

If anyone has any suggestions then they will be gratefully received.

 

[driver2000]

Unfortunately the problem (engine cut out leading to loss of power steering and reduced braking) has reoccurred.

This time my wife was driving. The engine cut out on a bend and she was unable to turn the steering wheel sufficiently. There was oncoming traffic who fortunately reacted in time and we all narrowly avoided a head-on collision. Of course without engine power the brakes are not as effective. We were then able to restart the car and drive as if nothing had happened to the engine.

The car is back into the dealership, who have carried out a test drive and run diagnostic checks. Given that I have driven around 2000 miles without any issues since the last problem I wasn't surprised when their test drive didn't reveal anything. And as last time the diagnostic checks didn't reveal anything either (so far).
Since the last time we had another problem with the auto gearbox (a message appeared saying to go directly to the garage). This was eventually traced to a faulty battery. It turns out that the car has two batteries, and the second battery was showing quite low voltage. This may or may not have had a bearing on the engine cut out problem. They replaced the battery.

The issue happening once can but put down to chance, possibly. But twice then I'm afraid I'm beginning to conclude that there could be a very serious potentially lethal defect with the car. Not surprisingly we don't want to drive the car until the problem is resolved.

The car is at the dealership and I will keep you all posted.

(By the way, Mobilo is of no use in these circumstances: they made it clear that if they find that the car can be restarted and driven when they arrive to recover the vehicle then you pay for the call out, and full costs of the recovery if you want it recovered. Last time I had to argue with them to get the car recovered and they accepted eventually but only because they accepted that the brakes could be faulty. This time I didn't bother and drove carefully to the dealer. Sadly this service is not as good as I have come to expect from other manufactures.)

If anyone has any suggestions then they will be gratefully received.

 

[kth286]

Yes I think you are coming to the same conclusion as myself that the steering does not lock but just feels as if it does because of no power assistance all of a sudden.

Ask the dealer if they can fit a data logger to your car until the fault happens again.

The fault will then be able to be identified better.

 

[Adam230K]

Can i suggest that you highlight to the dealer that this cutting out is related to turning, this might help them further, but i have no idea what it could be myself..

 

[ray_hennig]

Steering issues on heavy cars ...

Hello and my commiserations.

I had a similar issue some years ago on my 1991 300ce-24 and it was never diagnosed but, after numerous replacement parts (OV relay etc.) it went away.

Did your steering lock or was it just the removal of power assistance? For me, there's a difference because I'm a largish sort of chap but for my wife, and perhaps for you wife also, they are much the same thing.

Either way, and considering the age and price of your vehicle and the obvious safety concerns, I rather feel that your neighbourhood should now be infested with teams of brainy Germans with titles like "Herr Doktor" and "Dipl Ing" all beavering away to find the root cause of this sort of thing.

Or am I just over-sensitive?

Do let us know how this pans out.

RayH

 

[Dieselman]

When the engine cuts the brakes should operate as normal for about 5 applications before the servo loses all it's vacuum.

Can you or your Wife recall whether the turn was the same direction in all cases and exactly what position the key was in prior to turning off and restarting. Is it possible that the key isn't resting in the proper position for engine running, so jumps back a bit and loses connection.

Other than the crank sensor failing, the ECU must be receiving a 'stop' signal over the CAN, or simply losing power from the fuse box.
If the CAN became disconnected after the engine had been given a 'Go' signal, it wouldn't then stop on key request.

 

[219]

Could it not simply be that the load being placed on the engine by the power steering pump is causing it to stall whilst on the overrun ? On the new-fangled motors where fuelling is completely cut-off on the overrun is this not likely ?

Usually , the simplest explainations are the most likely ones .

 

[Dieselman]

Unlikely as the fuelling should come back on before the engine stalls and a 420Cdi has plenty of reserve of torque to overcome power steering load.

As it's an automatic it wont really be in over-run condition anyway.

 

[corned]

I think Dieselman may be on to something. Can the contacts in the ignition switch be faulty and cause a break in the ignition switch circuit? Could lateral movement (i.e. in a turn) cause the contacts to separate and thus kill the circuit?

 

[jaymanek]

loose battery terminal or bad earth strap somewhere.. sounds silly I know..

 

[stevesey]

Vectra's used to have the same problem with the engine stalling - caused by the idle control valve getting gummed up as a result of engine breather problems (factory mod was to fit a breather trap that went a long way to fixing the problem). Would typically happen when changing gear on the way into roundabouts (even on a friends auto) - followed by much heaving of the wheel and a very rapid re-start while still rolling.

I don't know how the idle control works on the 420CDi motor - separate valve or just the main throttle stepper motor? It might be worth a look.

 

[driver2000]

GL420 engine cut out and steering lost power

Thanks for the comments. In answer to the questions:

1) The first time it happened, the car was slowing down on a left hand bend. The second time: the car was slowing down on a right hand bend. Both times speed was about 25mph->30mph.

2) The steering did not lock but became very difficult to turn. On both occasions we were able to turn the steering wheel but with great difficulty.

3) The ignition key is in the On position when the car lost power.

To turn the ignition off requires a modicum of rotary force to overcome the click. There had been a suggestion that your knee could knock the key into the off position. I tried to do this after the last episode and concluded that that you couldn’t do it: first your foot has to be moved up and well away from the pedals in order to be able to knock the key with your knee. This cannot be an accidental movement. And second knocking the key simply moves it upwards. I couldn’t get my knee to cause the key to turn to the left.

4) Regarding Herr Doktor, my impression is that MB don’t want to know.

I have not found any posts on the MBclub forums on this but on the US forum (mbworld.org) there were 4 owners who had this problem on gl450 and gl550. In all cases the problem occurred as they slowed down either turning left/right or approaching a junction. Some had the problem more than once, none reported it resolved. The problem was first reported on the US forum in Feb 2008.

5) RE data logging. This seems the next step, but continuing to drive this car with a fault such as this could have tragic consequences.

Completely separately, we have also noticed a screech from the front nearside when braking and cornering on a bend with speed reducing from say 30mph to stop. The noise is not quite like a typical brake screech noise. It stops when the brakes are released (e.g during the turn). It only ever happens on a left hand turn. It started intermittently almost from new. I put it down to brake screech, but recently it had been happening more often and more noticeable. I don’t know if it is related but I’ve mentioned it to the dealer.

Given that it has happened to other cars in the GL range I would have thought MB would be on it. I read that Porsche undertook a major investigation of one of their cars after only 5 drivers reported an intermittent problem (not this problem).

Since the car went in for the crankshaft sensor recall (Dec 2008), this problem has occurred twice, and we have several other seemingly unrelated transmission related problems requiring the car to go to the dealer. Sadly I’ve seen better reliability from Volvos, Fiats and Bentleys.

I will be discussing with the dealer toady and will keep you posted.

 

[driver2000]

Update.

The delear has decided to open a case with MB, so that they can try to get to the bottom of this problem. One thing they mentioned is that it may be a faulty microchip in the key fob. In the meantime I have a courtesy car (not a GL though)

I will keep you posted.