[W126 Coupe] Suspect OVP relay

[Mike R.]

I think you're right about a bad reading and that a 1N4007 has the PIV
rating to handle the relay. If it was mine, I solder in the diode and give
it a go.
 
Later,
Mike R
 
From: mbcoupes-bounces at mbcoupes.com [mailto:mbcoupes-bounces at mbcoupes.com]
On Behalf Of Vance Rowley
Sent: Friday, June 12, 2009 9:01 PM
To: Mercedes Coupes Mailing Lists
Subject: [W126 Coupe] Suspect OVP relay
 
Just a quick update. I opened up the OVP and inspected the solder joints.
Looked OK, but went over the joints with some fresh solder anyway. Plugged
it in, but unfortunately I got the same results. The ABS/ASR lights still on
and the high rpm. I did notice one thing though while I was going over the
pc board with my meter. That is the small diode that connects to the relay
coil itself from pin 15 (no number on it, but looks like a 1N4001) was very
high resistance at around 9.6M while testing in the conductive direction.
The other direction looks fine and measured O/C as it supposed to. This of
course is possible, depending what kind of diode it is, but usually when
using a diode this way with a relay coil, a 1N4001-1N4007 should do the job,
which of course doesn't measure anywhere near as high as 9.6M in the
conductive direction. 
If anyone knows exactly what this diode is and what it should measure,
please let me know. I might just swap it out for a new one before I place
the order for my new OVP.
 
Regards,
 
Vance.
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