GP/Relay (Troubleshooting Help) - Page 2 - PeachParts Mercedes-Benz Forum

funola · #16 07-20-2010, 11:08 AM

The battery light should not be on when the ignition switch is off so I think you may have a problem with the ign switch itself. I had a car with a battery light that is always on dimly (only visible at night, engine running) that plaqued it's previous owner and he was unable to fix it. After a bit of trouble shooting I found the cause to be a loose connection at the starter motor big terminal. Tightened it down and that fixed it.

Your ign key problem is a different issue from the ign switch. After you take the tumbler out, give it a real good cleaning to remove the gunk that's built up inside by lube crap that's been sprayed in there, holding onto dirt/dust/brass dust and that's what hanging up the wafers in the tumbler making it harder and harder for the key to work. Use a small plastic container just big enough for the tumbler and spray WD-40 till it is submerged. Work the key in/out and see all the black crap that comes out. Keep doing that till no more crap comes out then do the same with hot water and dish washer detergent. Let it dry and do not lube it with anything and the tumbler should work like new (if nothing inside is damaged like a mangled spring).

holtonmusicman · #17 07-23-2010, 01:43 AM

Thanks guys! I've had little time to work on my car. I'm a school teacher and do auto work on the side to supplement my income. I've been busy fixing the brakes on a Mazda 626 that sat submerged in water . . . everything rusted beyond belief. And a few other vehicles since my last post . . . anyway . . .

I do believe the problem is in the ignition switch and I've also ordered a new(ish) glow plug relay as well.

I absolutely love this forum, the help and ideas I get are awesome! I checked the grounds and altenator (actually took it out and had it checked at Parts America) so I've pretty much narrowed it down to the ignition switch.

The switch looks pretty straight forward to replace . . . involved, but not difficult.

Again, THANK YOU guys, I'll re-post once I have all the parts (had to order the switch and won't be here until next week) and get it back together!

I'm sure I'll be posting again soon anyway, when I purchased the vehicle the A/C system was not functioning (actually it has been removed when the motor was rebuilt and never reinstalled). I have all the parts (plus a new compressor and dryer) so I'm sure I'll have some more questions when I start putting that back together!

Again, Thanks!

holtonmusicman · #18 07-29-2010, 05:27 AM

Well, the new ignition switch did not correct the problem of the battery light staying on after the key was removed.

I also made the mistake of ordering a used GP Relay . . . when I had no GP light after installing it I took the "new" relay apart to make sure it was making good contact and it just reeked of that "burn" smell . . . Live and learn.

Ordering a new relay which I hope will correct my GP Problem.

Any other suggestions on the Battery Light Staying on after the motor is off and key is out.

Someone suggested body straps but I cannot locate any on my 240D (1982)

The Altenator did feel very hot after just a few seconds of the engine running so I'll have that checked out next.

What a PITA!

holtonmusicman · #19 07-29-2010, 07:11 AM

Ok . . . so I removed, cleaned and reinstalled the body ground.

no difference.

Next step (for the battery light that is coming on when the vehicle is shut off) is to check the altenator/regulator?

The Battery light is ONLY on when the vehicle is off.

New Ignition switch and cleaning body ground has made no difference . . . the only thing left that is connected to the battery light is the altenator . . . correct??

funola · #20 07-29-2010, 10:16 AM

The key should shut off the light so something weird is going on. Try removing the wires to the alternator and see if the light go out. If it does, clean the alternator contacts and put the wires back and see what happens. If the light is still on then take out the alternator to have it tested.

note: don't forget to pull the positive battery terminal before pulling alternator wires.

holtonmusicman · #21 07-29-2010, 02:03 PM

I'm replacing the altenator . . . I'll keep you posted.

The altenator was/is over 10 years old . . . it may be good, but but replacing it I'll have better peace of mind down the road.

Got a 100 day warranty 65amp reman off ebay for $85 . . . not too shabby!

holtonmusicman · #22 07-29-2010, 02:57 PM

One problem "solved" . . . still clueless on GP relay problem.

I disconnected the wires from the alternator . . . light went out . . . so I'm assuming there's an internal short in the alternator somewhere.

The GP Relay now has a "new" symptom. While messing around and trying to trouble shoot using a new manual (from one of the members here) I unplugged the four prong pin and when I plugged it back in, the solenoid "clicked".

I did this again and then tested the GP's for voltage . . . all right on the money.

Leaving the key in "run" position, disconnecting the battery, then reconnecting does not make the GP solenoid "fire".

Only when I remove the four prong pin and replace it do I hear the GP relay working.

I can see no breaks or shorts in any of the wires coming from/to the four prong pin female connector.

Does this sound familiar to anyone else? Frustrating as heck! I've never taken a car to a mechanic in my life, but I'm about to that point as auto electrical is NOT my forte!!

holtonmusicman · #23 08-12-2010, 04:13 PM

Replaced the Alternator . . . fixed battery light problem.

Took the GP relay plug apart and crimped the connections (slightly) and that took care of the GP light problem.

I have a new ignition switch problem . . . but I'll do a search first before posting.

Love this sight and all the advice I get!!!

(sorry this took so long to get back to you guys, my computer was being repaired and I just got it back today)