W124 E280 Over Voltage Protection Relay

[mjtray]

I have heard that these relays are often problimatical on the M104 engined W124's.

Question, what does this relay look after and what are the symptoms if the relay is starting to pack up....anybody got a clue on this?

Cheers

Martin

 

[Andy]

Hi

The relay does what it says. It protects components, usually the engine ECU & the ABS ECU, from spikes in the ciruit. It provides the power to both these units. Hence when it plays up. Your vehicle dosn't start. Its also outside of the tests. So it does not show up on fault diagnostics.

Usually symptons is that the car won't start when hot and just switched off. Leave it for 10 mins or so & then it will start.


Hope this helps.


Regards

Andy @ www.mercedesservicing.com

 

[mjtray]

Andy,

Many thanks.......does sound like mine is packing up, ie does'nt like starting shortly after switching off when hot.

I'm also wondering if this is also why the car will die sometimes for no good reason. When this happens it will not re-start straight away, but will, if left for 5 minutes or so.

I have heard that the the original OVP relays were problimatical on the 124's and it appears that a replacement OVP has a slightly different part No.

Cheers