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'91 G300D SWB Manual, '99 ML320 7 seater
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Discussion Starter #1
Guys,

I have a problem with my diff-locks. The thing is that it all started today when I replaced the bulb of the front difflock switch. Every thing went hunky dory until this evening when I went to the car to test that all the switched had their lights functioning. With the engine off, I put the parking lights and saw that all of them were functioning. But then I checked that the yellow lights did also function -like I said without the engine running-. they lit OK but then I put the light switch to "off" and nothing happened. All the interior lights remained functioning, including all three yellow lights, until I press the button of the difflocks to unlock them. Any of them would make all interior lights to go off.

Problem is that everytime I put the lights on, all three diffs attempt to get locked. Naturally, I cannot drive the car in these conditions (at least not during the night). Again, the only way to have the diffs unlock is to switch the lights off and then press the switches to unlock. Any attempt to unlock the diffs with the lights on is useless. Having the engine running does not seem to make any difference.

Anybody can help? Mercedes garages around here are totally hopeless in anything GWagen and I don't know where to start from.

Needless to say that this is very urgent.

Regards,
 

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2000 G500 NMLE
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6,977 Posts
Not sure what it takes to change the bulb in the switch, but did you pinch or otherwise short something in the process?
 

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'91 G300D SWB Manual, '99 ML320 7 seater
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Discussion Starter #3
Dutch,

Not that I am aware of.

Just remove the switch, dismantle, replace bulb and put together again and connect.

Could this have been caused by me pressing the diff-lock switches without the engine running?

Regards,
 

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2000 G500 NMLE
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mortinson - 3/19/2005 5:31 PM

Dutch,



Could this have been caused by me pressing the diff-lock switches without the engine running?

Regards,
I don't think so. I've done it with my G500 and have had to ill effects.
 

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'91 G300D SWB Manual, '99 ML320 7 seater
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Discussion Starter #6
Mistery....

I went out again and put the parking lights on (without the engine running) with the key in the lock. All customary dashboard lights were on, plus the three yellow for the diffs and the danger sign (triangle) on the speedo which signals the diff locks on. Then I switched off the lights and all lights inside remained alight. Got out of the car and walked around it. No lights, except for those of the rear number plate (????????). then opened the passenger door and went to check the fuses in the footwell. After a while and without a warning all lights went off while I noticed a click somewhere in the relay tray beneath the fusebox.

After that went again to the driver's seat and but the lights on and off three or four times. No more yellow lights of the diff locks.

My only guess is that time limit relay of the difflocks is faulty (this is a pre-February 1994 truck).

Gosh, these are the beauties of electronics. In the good old days when a bulb wnet off it would never work again. You knew it was wrong. But now with these electronics you never know. This is just about the only bit of the 463 that I hate.

I'll keep you posted if it becomes faulty again...

Thanks for your help anyway.

Regards,
 

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G320 & E500
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1,193 Posts
mortinson - 3/19/2005 4:43 PM

Guys,

I have a problem with my diff-locks. The thing is that it all started today when I replaced the bulb of the front difflock switch. Every thing went hunky dory until this evening when I went to the car to test that all the switched had their lights functioning. With the engine off, I put the parking lights and saw that all of them were functioning. But then I checked that the yellow lights did also function -like I said without the engine running-. they lit OK but then I put the light switch to "off" and nothing happened. All the interior lights remained functioning, including all three yellow lights, until I press the button of the difflocks to unlock them. Any of them would make all interior lights to go off.

Problem is that everytime I put the lights on, all three diffs attempt to get locked. Naturally, I cannot drive the car in these conditions (at least not during the night). Again, the only way to have the diffs unlock is to switch the lights off and then press the switches to unlock. Any attempt to unlock the diffs with the lights on is useless. Having the engine running does not seem to make any difference.

Anybody can help? Mercedes garages around here are totally hopeless in anything GWagen and I don't know where to start from.

Needless to say that this is very urgent.

Regards,
It sounds like your running light circuit (the bulb) is shorting with the diff lock circuits.
The problems could also be that you are not grounded properly. This could create an open circuit for the other devices on the same connection. Feeding it backwords.

Chuck
 

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230 G BGS 300G TDI
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Hav you replaced the bulb with higher wattage. it can cause a resistance on the time delay that interferes with its opeoperation.
Take out the bulb you fitted and see how it is.
 

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'91 G300D SWB Manual, '99 ML320 7 seater
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Discussion Starter #9
Went for a test drive. All three diff locks worked perfectly. Then I put the lights on an locked all three diffs. Then tried to unlock them (with the lights on) but they wouldn't disengage. Then I switched off the lights and the diffs would disengage at the first touch of the button. The problem is that when I tried to recreate the problem it would not resurface again (after many attempts).

Anyway, it was clear at this point that the problem (inability to disengage the diff-locks) would only occur with the lights on so it more than likely that the cause was a short circuit that I inadvertenly created when I refurbished the difflock switch. This is also 4x4Rancher's opinion who very kindly rang me for help.

But since I was unable to buy a new switch on a Sunday afternoon, I decided not to let a 40 pence electric bulb beat me and I have dismantled the switch again and redone the connections this time in a more thorough manner which I hope will work.

I have retested the system again and all seems to work perfectly.....


Many thanks to you all,
 
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