[W126 Coupe] Suspect OVP relay (old subject-sorry)

[Vance Rowley]

Mak,

 Thanks for the tip. I think I will pry open the relay today and go over the 
solder joints. Makes a lot of sense. It's not too long ago that I had 
problems with my heater/aircon control box. After taking the unit out of the 
car and re-soldering some of the joints which looked bad, it worked 100% 
after reinstallation. I suppose it's just one of those things that you can 
expect to happen at the age of these cars. I just hope it doesn't happen 
with too many other electrical systems in the future. Anyway, I will let you 
know if re-soldering the OVP makes any difference.

Regards,

Vance.

----- 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: Friday, June 12, 2009 4:27 AM
Subject: Re: [W126 Coupe] Suspect OVP relay (old subject-sorry)



> Vance

> sometimes the OVP  relay has a cold solder joint  on the diode

> connection inside.car ,the fuse was ok.resoldered everthing back and

> all is well

> regards

> mak

>

>

> On 11/06/2009, Vance Rowley <vance.rowley at tiscali.co.uk> wrote:

>>

>> Hi Mike,

>>

>>   Yes, the fuse is OK, and the voltage with the engine running seems OK 

>> at

>> 13.9v. Also, thanks very much for the offer of the OVP, but 

>> unfortunately, I

>> am located in the UK (although I do sometimes visit Vegas each year in

>> November during the Global Gaming Expo), sadly I don't think I will be 

>> going

>> this year, and of course I am hoping to get the problem sorted before 

>> then

>> anyway. Thanks again for the offer, all help is always appreciated. I 

>> must

>> remember to look you up next time I visit.

>> One more thing is, I have noticed there are a few variations of the OVP

>> (different part no's, some with one fuse, some with two), but from what I

>> can tell from the little circuit diagram on the side of my relay (201 540 

>> 32

>> 45) and comparing it with the photos of others I have looked up on the 

>> net,

>> it doesn't look as though it makes any difference as long as it will fit

>> into the socket. In fact when I looked up my part number on a UK based 

>> parts

>> supplier, it returned part no 201 540 37 45, one with two fuses and a red

>> top with an additional circuit which would be redundant if plugged into 

>> my

>> socket. From what I can tell, this should be fine as the first circuit 

>> looks

>> the same. Am I correct about this?

>>

>> Cheers,

>> Vance

>>

>> ----- Original Message -----

>> From: Mike R.

>> To: 'Vance Rowley' ; 'Mercedes Coupes Mailing Lists'

>> Sent: Thursday, June 11, 2009 2:44 PM

>> Subject: RE: [W126 Coupe] Suspect OVP relay (old subject-sorry)

>>

>>

>>

>> Have you checked the fuse in the OVP? A blown fuse will create the high 

>> idle

>> (BTDT.

>>

>>

>>

>> What's the battery voltage with the engine running? When my ABS & Battery

>> light come on at the same time, my alternator has died and the battery

>> voltage is too low.

>>

>>

>>

>> Where are you located? I think I have an OVP you could borrow/buy.

>>

>>

>>

>>

>> Later,

>>

>> Mike Ramay

>>

>> (702) 494-8056

>>

>> Las Vegas

>>

>>

>>

>>

>> From: mbcoupes-bounces at mbcoupes.com

>> [mailto:mbcoupes-bounces at mbcoupes.com] On Behalf Of Vance

>> Rowley

>> Sent: Thursday, June 11, 2009 5:56 AM

>> To: Mercedes Coupes Mailing Lists

>> Subject: [W126 Coupe] Suspect OVP relay (old subject-sorry)

>>

>>

>>

>>

>> I know this subject has been covered many times, but there doesn't seem 

>> to

>> have ever been any exact diagnoses, and appears to be some confusion on 

>> the

>> subject.

>>

>>

>> The symptoms are as follows on my 1991 560 SEC (Euro).

>>

>>

>>

>>

>>

>> 1. Takes a long time to start, (where it used to start on the first 

>> couple

>> of turns of the engine.)

>>

>>

>> 2. High idle, around 1400-1600 rpm (and sometimes creeps up).

>>

>>

>> 3. ABS and ASR warning lights on all the time.

>>

>>

>> 4. Hesitate slightly when you hit the gas. (more noticable when you rev 

>> the

>> engine in neutral)

>>

>>

>>

>>

>>

>> This I believe is the typical (limp home) mode. I have seen these 

>> symptoms

>> on many forums as well as our archives, but never usually all at the same

>> time. Also, these symptoms that other people have are usually 

>> intermittent,

>> where mine are permanent. Anyhow, there are quite a few different 

>> diagnoses

>> for these symptoms around on the net, but mostly point towards the

>> overvoltage protection relay. I have of course checked the fuse in the 

>> top

>> of the relay and is OK, as well as making sure the pins are clean, which 

>> of

>> course they are. Have even tried one tip to disconnect the battery 

>> overnight

>> to try to reset the system. No joy.

>>

>>

>>

>>

>>

>> My main question (before I purchase a new OVP relay) is, can anyone 

>> confirm

>> that this is the problem for sure. Also, I unplugged the relay and 

>> started

>> the car and all the above symptoms remain the same without the relay even

>> plugged in. This got me thinking. Does this mean if you unplug the OVP 

>> relay

>> on a known good working car, that you will get all the above symptoms? 

>> This

>> would surely confirm the diagnoses and was wondering if anyone has done 

>> it.

>> If so, please let me know, as well as any other tips or hints.

>>

>>

>>

>>

>>

>> Thanks,

>>

>>

>>

>>

>>

>> Vance.

>>

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>> 06/10/09

>> 18:30:00

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>