Location of OVP relay
Could someone point me to the precise location of the OVP ('91 W463 300GES). A diagram might be useful.
My techie seems to have gone walkabout and I'd like to get the wagen running.
I've checked the fuses and they seem to be ok.
I'm asking for precise location as I'm not physically very able these days and it's very difficult spending any time poking about.
Thanks folks.
Easy,But perhaps not that kind on your back. Find fuses, undo the two self tapping screws that hold the the fuse box/ flap so it falls downwards, you will see ovp , yours probably has one fuse on the top, replacements seem to have two fuses. Think you will need 7 or 8 mm spanner to loosen nut holding relay in place
Could someone point me to the precise location of the OVP ('91 W463 300GES). A diagram might be useful.
My techie seems to have gone walkabout and I'd like to get the wagen running.
I've checked the fuses and they seem to be ok.
I'm asking for precise location as I'm not physically very able these days and it's very difficult spending any time poking about.
Thanks folks.
I have no idea where it is , but if your problem is that the car is not starting. Try this and see if ithis technique will sort it out. :
With the key in the OFF position.
Disconnect the negative pole in the battery momentarily and then reconnect it.
You might here some "clicking sounds" I think they come from the relay box direction.
Then try the key start.
I think that by de-energizing the relay, it resets it and the engine will start. It works with me every time. I had the problem for nearly one year. No mechanic or electrician has yet found out what is wrong.
It does start, it's just that it is difficult to start.
Hi Ian
The cold start regulator on the K Jetronic is controlled by the Over Voltage Protection relay (OVP), this is the large relay with the twin fuses on top. It is found behind the fuse board under the dash on a 463.
When the OVP fails the cold start procedure fails to operate and it is like starting the vehicle without a choke. It requires much cranking and when the engine does eventually catch it runs very badly and any attempt to use the throttle stalls the engine. After several attempts the engine will have warmed sufficiently to gently apply the throttle and gradually build the revs and then maintain them to allow the engine to obtain operating temperature after which it can be driven normaly.I think that this may match your cold start symptoms.
The problem with finding that the OVP is at fault can be tricky because it does not fail completely but starts off with an intermittent fault, some days it starts fine the next day it doesn't. In the 463 it is easier to diagnose because when the OVP fails to operate the ABS light normally stays illuminated. You could also test it was operating by touching the OVP housing as you activate the ignition, if you feel it click then it is operating. I am sure that it could be checked out of the car with a meter but I don't know how to do this.
Hopefuly this will be of some help because an OVP problem can be very difficult to diagnose.
Doug.
Hi Ian
The cold start regulator on the K Jetronic is controlled by the Over Voltage Protection relay (OVP), this is the large relay with the twin fuses on top. It is found behind the fuse board under the dash on a 463.
When the OVP fails the cold start procedure fails to operate and it is like starting the vehicle without a choke. It requires much cranking and when the engine does eventually catch it runs very badly and any attempt to use the throttle stalls the engine. After several attempts the engine will have warmed sufficiently to gently apply the throttle and gradually build the revs and then maintain them to allow the engine to obtain operating temperature after which it can be driven normaly.I think that this may match your cold start symptoms.
You have exactly described the symptoms I am currently experience.
The problem with finding that the OVP is at fault can be tricky because it does not fail completely but starts off with an intermittent fault, some days it starts fine the next day it doesn't. In the 463 it is easier to diagnose because when the OVP fails to operate the ABS light normally stays illuminated. You could also test it was operating by touching the OVP housing as you activate the ignition, if you feel it click then it is operating. I am sure that it could be checked out of the car with a meter but I don't know how to do this.
Yup, the ABS lamp is permanently illuminated.
Hopefuly this will be of some help because an OVP problem can be very difficult to diagnose.
Doug.
Bang on the money there Doug thanks. I'll have a look at the OVP when I'm able to. If the fuse has gone I'll replace it. If that doesn't do the job I'll replace it as it would appear to be the culprit.
Thanks again.
M'bones and the weather permitted a shoofty at my ailing G today. Found the OVP without difficulty and the fuse is blown.
All good so far, just awaiting new fuses from fleaBay.
One thing puzzles me, the OVP had a 20A fuse in it, but the unit itself has 10A written on it. Still it's been working fine with a 20A fuse so I guess I'll replace it with same.
Thanks for all the help.
Hmmmm - don't want to put a downer on this but if the OVP is only rated at 10A and the 20A fuse has blown it's likely that the OVP will have been damaged/blown.
Fingers crossed that's not the case but (in my view anyway) better to try it with a 10A fuse first and if all OK then run it with that.
There's a reason why MB didn't just fit 32A fuses everywhere rather than using different ones for different circuits.
You may well be right, I'll try it with a new 10A fuse when they arrive and fit a new one if necessary.
Can anyone confirm the OVP part number? I think it's 201 540 32 45. I ask as my unit is not MB.
Thanks.
Resolved. Found a 10A fuse and all is well. Just need to sort iut the radio now.
Thanks for all the help.
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Easy,But perhaps not that kind on your back. Find fuses, undo the two self tapping screws that hold the the fuse box/ flap so it falls downwards, you will see ovp , yours probably has one fuse on the top, replacements seem to have two fuses. Think you will need 7 or 8 mm spanner to loosen nut holding relay in place
I thank you, my back doesn't !