[W126 Coupe] SEC Starting Failure After a Massive Downpour

[Dick Spellman]

That green coaxial wire is the crank position sensor.  If that cable is in
anyway damaged you'll get NO SPARK as the ignition control unit needs to see
the interrupt from that crank sensor.  Change or blow dry that cable
complete with sensor first.   Moisture could impede the signal if you have
the shield and the center conductor passing voltage, these should be
isolated from each other.

Dick
----- Original Message ----- 
From: "a figment of the imagination" <figstir at yahoo.com>
To: "Mercedes Coupes Mailing Lists" <mbcoupes at mbcoupes.com>
Sent: Monday, August 15, 2005 12:37 PM
Subject: Re: [W126 Coupe] SEC Starting Failure After a Massive Downpour


> Hi!
>
> Thanks for all the suggestions.
>
> I replaced the fuel filter and re-installed the entire
> fuel pump system under the car.  I think I truly
> wasted my time and money here because the fuel filter
> was putting out good clean flow and the pump worked
> fine and dandy.  I'm glad I didn't buy the $180 fuel
> pump!
>
> However, as it so clearly points out, the car did not
> start after this.
>
> In today's rain, I noticed that water may have gotten
> into the ignition control module.  The rubber black
> cap to the green wire that goes under the the dizzy
> cap unit is cracked.  However, I think all the
> shielding   to the wire is fine, but it is possible
> some water/moisture may have somehow entered in some
> paranormal way no matter how highly doubtful it seems.
>
>
> 1) I'll go ahead and replace the ignition coil cable
> to the dizzy cap center terminal and check the green
> wire and see if this works.  I have an old coil as
> well and old ignition control module (pretty
> expensive, I'll say!!!!) from a previous benz.  [My
> current car is a '82 380 SEC (old but sweet!) with an
> interior that's been upgraded to '90 560 SEC and a
> valve job that I did for $85!!!, including camshafts
> and rocker arms.]
>
> Unfortunately, I simply don't know how to test the
> ignition coil cable without getting electrocuted.
> I've been electrocuted enough times to know that it
> hurts (my heart, too!).  I'm thinking of just placing
> my Fluke meter across the contact leads to the coil
> (the terminals with the phillips head screws that sit
> on top of the frame on the engine belly).  I've heard
> about people doing crazy stuff like jamming
> screwdrivers/pliers into the distal terminal of the
> ignition cable and putting it against the valve cover
> caps or distibutor, but I think that it's a tad bit
> frightening just to create an arc to test these
> contacts.    However, I don't know how else to test
> this without doing a "blind" replacement of the
> cable/coil/module or checking the
> resistance/continuity of the cable.  Can someone help,
> please?
>
> Regarding the Bosch platinum spark plugs, I use the
> old ones (platinum 2's???, they have the single point
> but are simply platinum metal).  I have stayed clear
> of the platinum 4's because, first of all, I think it
> is an absolute gimmick that makes no sense from an
> electrical stand-point!!! The added effect must be
> close to nil.).  Many import part stores in SoCAL
> recommended Bosch platinum,  so I've stuck with them
> since.  I did not know that they are not recommended
> by MBZ, but this may only apply to the Plat. 4's.
> Where can I read about this information?
>
> 2) I'll check the relay under the fuse box.  That's a
> pricey relay at ~$400+ (if I remember correctly), but
> perhaps it got a little loose or wet and can be
> re-seated.
>
> Anyways, right now I'm left trying to figure out how
> to test my ignition coil cable without getting
> electrocuted.  Any clever tricks?
>
> Thanks again.
>
> -figstir
>
>
>
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