ABS warning, fuse blowing, smoke emitting

[Ian Macleod]

Hello all

I've got a problem with my E430 Avantgarde Saloon 1998.

The ABS (EPS etc) lights come on when I startup and stay on.

My independent repairer is struggling. The computer diagnostic kit said it was a Steering Angle Sensor problem. This was replaced but the warning lights remained.

Further investigation showed that a fuse had blown. It seems that this should have been a 7.5 amp fuse but a 15 amp fuse had been used. Replacing the fuse with another 15 amp fuse resulted in it immediately blowing again and smoke was observed from somewhere near the front of the car. A third, 7.5 amp, fuse was installed.

Since then it has not been possible to recreate the fault but it is clearly not a good idea to take the car back on the road until we find what I would assume is a transient short somewhere.

The engineer is currently combing through the whole loom.

Any ideas on where to look for the problem would be gratefully appreciated.

Thanks in advance for your help.

Ian

 

[television]

I am short of time this week,if it will wait I can give a hand next week.

malcolm

 

[Ian Macleod]

Thanks Malcolm. I fear it will somehow be all over by next week but anything you can contribute, at any time, will be most welcome.

Ian

 

[Ian Macleod]

Finally diagnosed, and fixed.

 

[Blobcat]

What did they do?

 

[Ian Macleod]

Sorry for the delay in posting this resolution message.

The problem lay with the factory fitted security alarm siren! On my car this is sited down by the front offside wheel - a most exposed position. There was a crack in the casing and in extreme conditions water started to fill the casing.

The ABS circuits run from the same power as the security alarm. The first time it blew and the ABS/ESP light came on and stayed on I remember now was in sheeting rain and what I thought was condensed rain on the bonnet forming steam must have been smoke from underneath.

The second time it blew (when my independent engineer was replacing the fuse) it seems that the damage to the siren connection and indeed other wires in the loom was such that on fitting a third fuse the ABS light remained off.

It took a wire by wire search to get to the bottom of all this and quite a time to get the correct replacement siren and wiring loom but all is now fine.

I would be interested, though, in any comments on the following suspicion of mine that results from all this.

In a previous stream starting on 25/9/2002 under the heading "E430 ABS Warning Light" you will see that on an earlier occurrence of this problem the stealership came up with the same initial diagnosis and fitted a new steering angle sensor. Is it possible that this turned out not to be the problem and they found that by fitting a 15 amp fuse instead of a 7.5 amp one they were able to mask the problem?

 

[television]

Is it possible that this turned out not to be the problem and they found that by fitting a 15 amp fuse instead of a 7.5 amp one they were able to mask the problem?

That jump from 7 to 15 is massive, I doubt if the cables are capable of carrying double the current, In many electronics as fuse has been re rated, but never double.

Malcolm