W124 - Over Voltage Protection Relay

[howzat1976]

Hi All

Need some help with my W124 1992 E300-24V, it starts from cold when warmed up it begins to stall at low revs until it cuts out. It then only starts from cold. Now it cuts out almost straight away (after 3/4 miles), I've been told it could be the Over Voltage Protection Relay, then the AA said its the Crank shaft sensor.

The car is in mint condition with only 78k on the clock.

Any ideas?

Vass

 

[wireman]

There is an issue with OVP relays, they are fitted to protect the electronic bits of ABS and Engine management etc against the effects of disconnecting the battery while the engine is running or any such potential source of excess supply voltage which may damage the modules.

The fault (pointed out to me by television/Malcolm) is the soldered connections on the internal circuit board with soldered joints becoming cracked at the relay coil connections, to open up the relay and resolder the PCB is the cure.

The relay has two functions:- One is to blow the fuse on its lid if overvoltage occurs.
The other is to switch on the protected systems in response to a signal from such as the ingition and fuel pump relay, it is this function affected by the solder problem.

If its the OVP relay the ABS light will come on, if the crankshaft sensor is at fault this will not occur.

 

[howzat1976]

Thanks for the reply, so it looks like it's the crank shaft sensor. No ABS light comes on, would the crank shaft sensor have the same symtoms that I mentioned.

Vass

 

[lizzee868]

runs rough

My car takes ten minutes to start when cold, what should I do? My abs light is on and low idle

 

[WG M-B]

I would get it checked properly before guessing. The cps would stop the ignition amplifier from operating.
This would cut the car dead and it would not restart.

 

[television]

Rough low idle and ABS lamp on is more than often the OVP relay

 

[rpe2]

As the OP doesn't report the ABS lamp on, I'm with WG - get some diagnostics first. If funds are an issue, I'd start by checking the dizzy cap for cracks/ moisture.

 

[jonthetourist]

As the OP doesn't report the ABS lamp on, I'm with WG - get some diagnostics first. If funds are an issue, I'd start by checking the dizzy cap for cracks/ moisture.

Always a good place to start with this engine.

Jon

 

[television]

As the OP doesn't report the ABS lamp on, I'm with WG - get some diagnostics first. If funds are an issue, I'd start by checking the dizzy cap for cracks/ moisture.

The op says the ABS lamp is on

 

[syncropaddy]

As the OP doesn't report the ABS lamp on, I'm with WG - get some diagnostics first.

I dont suppose you noticed that the OP posted this thread over five years ago! The recent answers are to the poster who has a 560 in America who resurrected the post today!

If funds are an issue, I'd start by checking the dizzy cap for cracks/ moisture.

And if funds aren't ..... ?

One cure for the rich and one for the poor!!