93 300E Starter Problems
 

1993 300E Somehow ended up with lot's of water on the passenger floor (1st time ever) and now have a starting problem. When the key is moved to the start position, you just hear the starter seloniod click. If you jump the selonioid , it cranks strong and starts ok, So the starter and battery are ok.

I did some archive reading here and discovered the neutral safety switch may be suspect. I think I jumped the correct switch (right side of auto trans 2 wires) with no improvment. I dried up the water, blew every connection out on the passenger side floor with compressed air, still nothing. Any ideas before I go crazy ?? As usual thanks in advance.. Rollin

Update----- I tried jumping the middle pin on the starter connector ( just in front of the brake booster) to 12v and it cranked great. Then I turned the key to start and measured the voltage on the other side of the connector and got 12 volts. So I must have low current at that connector. Should I have 12 volts on one side of the neutral safety switch ? I think I'm getting close to solving this, does anyone know the power path to the solenoid ? Does it go to the ignition switch then the safety switch or vise versa ? Are there any schematics online ? Thanks Rollin

Try N instaed of P on gear selector..........

Tried starting in N or P, no change

NSS is on left side of trans..

4 wires .. two for back-up lamps and 2 for starter lock-out.
The other possible is K-38 relay if car has Alarm System..

Thanks Arthur, I jumped the neutral switch with no improvment. Where is the relay located ?? Thanks Rollin

Forgot to add, yes it has the factory alarm system. When everything got wet, the alarm horn went off, but the car would still run. The alarm horn problem solved itself after about 10 minutes. I think we are getting close to solving this..... Thanks

Behind the speedo console

Jump the leads at K38 [ 1/3] for a test.

I will see if I can find the schematic

http://mb.braingears.com/124_DISC1/Program/ETM/2415100.pdf

...you will see the series circuit chain.. ..ign sw to NSS, to K38, etc.............

You may also have a bad ignition sw , but K38 is the present suspect

Thanks very much Arthur, I will try K38 when I get home from work and post my resuts. Thanks Rollin

Don't forget to check fuse #8 first..that is feed for K38........

Also, if you look at the schematic , right hand corner..you will see that the Canadian versions did not have Alarm and they just jumper that circuit..so, if you find a problem with your ATA , you can do the same at K38..lots of guys do just that to eliminate the K38 b/c they are troublesome as they age...........

I there an easy way to get to K38 ? Thanks Rollin

**** Update **** Problem Solved !!

Although fuse #8 looked ok and ohmed out ok, I cleaned both ends of the fuse with a small wire brush, put it back in and the car cranked. Only thing I can figure it was passing voltage but only a small amout of current, not enough to close the relay. I've started the car about 15 times now with no problem.

Thank you very much Arthur !!!

Great
Now you can see why I mention to test both sides for power when testing the fuses .. Benz fuses always fool ya.. we always just give them a twist in their socket for just that reason..

I would print that schematic out and put it in the glove box for future K38/NSS tracking...........
Even if you only need it to show to your mechanic.