obscure electrical problem on my 82 300cd - PeachParts Mercedes-Benz Forum

t walgamuth · #1 01-21-2011, 04:21 AM

The lovely daughter #4 has my cd in Muncie, going to Ball State. Last night she called and it won't start and when she tried after letting off the key the dash lights wouldn't go off.

I guess it had been acting up for a while but she never mentioned it because it always started....(duh!).

I suspect either a loose starter cable or bad solinoid.

Comments?

layback40 · #2 01-21-2011, 04:52 AM

Quote:

Originally Posted by t walgamuth

The lovely daughter #4 has my cd in Muncie, going to Ball State. Last night she called and it won't start and when she tried after letting off the key the dash lights wouldn't go off.

I guess it had been acting up for a while but she never mentioned it because it always started....(duh!).

I suspect either a loose starter cable or bad solinoid.

Comments?

I would be considering the ignition switch. The dash lights should have no power when the switch is off.
I am not sure if they are controlled through a relay. If so the relay may be sticking. She needs to disconnect the battery & reconnect & see if that fixes the gremlin.
The no start sounds like the power to the GP controller is bad. Assuming it still cranked. This could also be the ignition switch.

Does she have a boy friend there who you can discuss the problem with?

#3 01-21-2011, 08:34 AM

I agree, it sounds like the electrical portion of the ignition switch failed. Sometimes the little keyway between the main ignition switch and the electric part fails so you have to replace both. Does the key feel "loose" like the spring return is disconnected?

t walgamuth · #4 01-21-2011, 09:59 AM

She says it is loose and does not spring back as it should from the start position.

(As far as her boyfriend, I think talking to her is more productive in this case. She is pretty mechanical and he is not at all.

)

t walgamuth · #5 01-21-2011, 10:01 AM

Quote:

Originally Posted by layback40

I would be considering the ignition switch. The dash lights should have no power when the switch is off.
I am not sure if they are controlled through a relay. If so the relay may be sticking. She needs to disconnect the battery & reconnect & see if that fixes the gremlin.
The no start sounds like the power to the GP controller is bad. Assuming it still cranked. This could also be the ignition switch.

Does she have a boy friend there who you can discuss the problem with?

It does not crank, click or whistle (the whistle thing is a joke)

winmutt · #6 01-21-2011, 10:06 AM

Yup classic ignition switch failure.

t walgamuth · #7 01-21-2011, 10:08 AM

So I need the electric portion of the ignition switch?

winmutt · #8 01-21-2011, 10:10 AM

In all likelyhood the mechanical. Bring both just in case.

#9 01-21-2011, 10:15 AM

Quote:

Originally Posted by winmutt

In all likelyhood the mechanical. Bring both just in case.

Yes, the likely failure is the connection between the mechanical and electrical pieces; it's a pretty flimsy metal keyway. You will probably need both parts. Once you remove it, you will be able to start the car by manually turning the electrical part. It might be easiest to just send her to the dealer.

funola · #10 01-21-2011, 10:19 AM

Does the CD have the terminal block on the passenger side wheel well where you can jumper the starter solenoid? If so, have her jumper it when the ign switch is in the run position, to enable glow plugs and fuel. If it cranks, the ign switch is ng.

t walgamuth · #11 01-21-2011, 10:51 AM

Quote:

Originally Posted by Craig

Yes, the likely failure is the connection between the mechanical and electrical pieces; it's a pretty flimsy metal keyway. You will probably need both parts. Once you remove it, you will be able to start the car by manually turning the electrical part. It might be easiest to just send her to the dealer.

I am thinking of having the parts shipped to her house tomorrow and going over and putting it in myself. I can do that just sittiing in the seat right? I don't need the specail key tumbler? If I need that that will take a few days right? what tools do I need? anybody done it lately?

#12 01-21-2011, 11:05 AM

I did it a year or so ago. If the key still turns, you can remove the tumbler with a paper clip and unscrew the ring around the tumbler. To remove the ignition switch assembly, you need to remove the under dash and push the cluster out. The assembly has to be disconnected from the steering column by loosening a clamp and depressing a little pin. It's pretty tight under there, but I was able to do it in about 1/2 hour. Once the assembly is removed, you can unscrew the electrical part from the main part. It's pretty obvious when you are looking at it.

Assuming the tumbler is OK, you can reinstall it in the new assembly.

funola · #13 01-21-2011, 11:21 AM

I would suggest doing more testing BEFORE replacing the elec ign switch. Put a voltmeter on the small wire of the pass wheel well terminal block (wire 2.5 VI). If you do not get 12V there when ign switch is turned to start, the starter lock out switch OR the ignition switch is no good. Next, put the voltmeter on the lockout switch (wire 2.5 VI/WT). If you do not get 12V there when ign switch is turned to start, then the (elec) ignition switch is no good.

barry123400 · #14 01-21-2011, 11:37 AM

Quote:

Originally Posted by t walgamuth

She says it is loose and does not spring back as it should from the start position.

(As far as her boyfriend, I think talking to her is more productive in this case. She is pretty mechanical and he is not at all.

)

You are not alone Tom. None of our four daughters attracted mechanical types. Or perhaps better explained as never getting their hands dirty when younger. Some have mechanical design capabilities though. Even engineering degrees in the mechanical engineering field.

winmutt · #15 01-21-2011, 11:38 AM

Quote:

Originally Posted by funola

I would suggest doing more testing BEFORE replacing the elec ign switch. Put a voltmeter on the small wire of the pass wheel well terminal block (wire 2.5 VI). If you do not get 12V there when ign switch is turned to start, the starter lock out switch OR the ignition switch is no good. Next, put the voltmeter on the lockout switch (wire 2.5 VI/WT). If you do not get 12V there when ign switch is turned to start, then the (elec) ignition switch is no good.

If the key isnt turning back it is a mechanical failure not electrical...

All you need is a properly sized paper clip (the jumbo clips are just right), 10mm(?13mm) wrench/socket (it can be tight in there) and something to push the button in on the steering column. The kick panel has to be removed and pushing out the gauge cluster makes it much easier.