[W126 Coupe] Suspect OVP relay (update)

[kabed1980 at yahoo.com]

When I finally got to my 560after 7 years of sitting not running I finally got to u got it running bitter then new I had the run in with the alternator same description 
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-----Original Message-----
From: "Iain Gunn" <igunn at bmts.com>

Date: Wed, 17 Jun 2009 19:08:54 
To: Mercedes Coupes Mailing Lists<mbcoupes at mbcoupes.com>
Subject: Re: [W126 Coupe] Suspect OVP relay (update)


Here, let me tell you another one that will throw you.
Speedometer starts bouncing all over the place, all gages start going 
erratic, everything starts shutting down, blower motor goes on to high heat. 
Think you're in the "Close Encounters of the Third Kind" movie?

Brushes in the alternator, or alternator.

Anyone got more for the new guy?
----- Original Message ----- 
From: "Afzaal Khan.M" <afzaal53 at gmail.com>
To: "Vance Rowley" <vance.rowley at tiscali.co.uk>; "Mercedes Coupes Mailing 
Lists" <mbcoupes at mbcoupes.com>
Sent: Tuesday, June 16, 2009 9:04 PM
Subject: Re: [W126 Coupe] Suspect OVP relay (update)



> Great!  fault diagnosed and  rectified.

> mak

>

> On 16/06/2009, Vance Rowley <vance.rowley at tiscali.co.uk> wrote:

>>

>> Yes, at last, confirmed. Received my new OVP relay this morning and 

>> before

>> the delivery truck had driven away, I had the parcel ripped open and 

>> fitted

>> the relay. My thoughts as I was about to turn the ignition key was "well,

>> here goes" But as soon as I did, I could tell that this is it, as the 

>> engine

>> started immediately and the ABS/ASR warning lights went out. It used to 

>> take

>> around 10 seconds or more of the engine turning over to start with the 

>> old

>> relay. The engine was very smooth and no stumble or hesitation when 

>> revving

>> the engine. The idle was fine also.

>> I know that the OVP gets blamed for everything, but it looks like if you

>> have the 4 symptoms all at the same time.

>> 1. Takes a long time to start

>> 2. High Idle

>> 3. ABS/ASR warning lights remain on.

>> 4. Rough running of the engine.

>> Then it looks like the problem is almost certainly the OVP relay. Of 

>> course

>> it is possible that the fuse is just blown, but if that is OK (as mine 

>> was)

>> then a new OVP should be the next step.

>>

>> For those who want to have a go at repairing the relay, from what I have

>> discovered along with input from this group, it looks like if you get all

>> symptoms at the same time, then as long as the fuse, relay coil, contacts

>> and solder joints are OK, then the most likely culprit is the diode

>> connected between pin# 15 and the relay coil. It is unlikely that the 

>> zener

>> diode is the problem, as this would more likely blow the fuse if the 

>> zener

>> was at fault. If you get only 1 or 2 of the above symptoms, then a solder

>> joint (or more) would be most likely.But of course when you get only 1 or 

>> 2

>> of the symptoms, say for example the ABS warning light on, then it's

>> possible the OVP is fine and that the problem could be the ABS computer

>> itself. It's understandable that the OVP gets blamed for everything, but 

>> is

>> certainly the first thing to check.

>>

>> Thanks again to everyone who gave their input.

>>

>> Regards,

>>

>> Vance.

>> The MB Coupes Website!

>> W126 SEC Mailing List

>> Postings remain property of MB Coupes, L.L.C.

>>

> The MB Coupes Website!

> W126 SEC Mailing List

> Postings remain property of MB Coupes, L.L.C.

> 


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