[W126 Coupe] Suspect OVP relay (update)

[Jonathan Hodgman]

Could be reg, could be alt..  Pull your reg see what you have..

Bosch only, no KAE.


Iain Gunn wrote:

> 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.

>>

>

> The MB Coupes Website!

> W126 SEC Mailing List

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

>



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