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  #1  
Old 12-16-2011, 07:13 PM
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1985 300 SD theft alarm

Every time I put my # 15 fuse in the anti theft alarm goes off. How do I reset this thing? Is it worth haveing or should I just unplug it. If I need to unplug it where is it located? Thanks in advance for your help. Jack

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  #2  
Old 12-16-2011, 08:27 PM
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Another problem I am having with my new 1985300 SD. is that when I turn on my lights I only have a bright light on left side and the bright light indicator is staying on no matter what way I push or pull the lever. Again the car has been sitting for 2 years. Does this sound like the dimmer switch or light switch?
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  #3  
Old 12-16-2011, 10:24 PM
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Theft alarm disabled

I disconnected the theft alarm that I found under passenger floorboard. Now my problem still remains with headlight issue. When I turn on the lights the left only burns on bright high beam, and if I move the dimmer lever it stays the same. I have no power on #6 or #8 fuse. I checked my 84SD and when I turn on lights I have power to the fuses. Could someone point me in the right direction? I cannot find a DIY on the forum. Help please.
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  #4  
Old 12-16-2011, 10:31 PM
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Have you pulled and replaced all the fuses and cleaned the contacts?

Without that step, you're just wasting everybody's time..........including your own.

And, I'm sure you already know the deal with the fuses...........
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  #5  
Old 12-16-2011, 10:59 PM
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Usually, it is necessary to pull the fuse and inspect it as they are prone to cracks in the fusible link. (This is usually due to the PO, or someone else, spinning them to make contact.) Replace with copper fuses, instead of aluminum, and most of the intermittent fuse problems will be resolved.
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84 300SD 350K+ miles ( Blue Belle )
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  #6  
Old 12-16-2011, 11:13 PM
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I cleaned the fuse holders and tried different fuses. I would think that I should have power on one side of the fuse checking it with a circuit tester. In the morning I plan to compare the 84 and 85 side by side. I think I should get power from light switch to turn signal lever, then to fuse, then to headlight. I that correct?
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  #7  
Old 12-16-2011, 11:24 PM
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If you have no power on 6 or 8, the problem is either the headlight switch or the combination switch.

Easiest thing to do is to pull the combination switch and see if the headlight switch is feeding power to it. You're looking for a heavy wire (2.5mm) white in color, with a yellow stripe.
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  #8  
Old 12-16-2011, 11:40 PM
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Power splits at the combination switch, to the fuses and then, to the headlights. Your symptoms point to either a fuse problem or combination switch. You might have some mild corrosion in the combination switch and it just needs to be cycled several times to get things working again. Mine has turn signal issues if it sits for very long. After several cycles, everything starts behaving as it should.
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84 300SD 350K+ miles ( Blue Belle )
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  #9  
Old 12-16-2011, 11:59 PM
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combination switch

How hard is it to remove the combination switch? Can you spray these things with contact cleaner or something? Is there a DIY on this? Thanks for your input.
Jack
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  #10  
Old 12-17-2011, 01:09 AM
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I don't know if there is enough access for contact cleaner to be effective. From what I discern, removal of the combination switch (on the W126) requires removal of the steering wheel. Some have said this was fairly easy and others not so easy. Personally, I have never done it on this car so I can't attest to either.

Since removal of the combination switch appears to be involved, I definitely would give contact cleaner a shot first. Who knows, we get lucky sometimes.
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84 300SD 350K+ miles ( Blue Belle )
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  #11  
Old 12-17-2011, 08:23 AM
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Quote:
Originally Posted by SD Blue View Post
I don't know if there is enough access for contact cleaner to be effective. From what I discern, removal of the combination switch (on the W126) requires removal of the steering wheel. Some have said this was fairly easy and others not so easy. Personally, I have never done it on this car so I can't attest to either.

Since removal of the combination switch appears to be involved, I definitely would give contact cleaner a shot first. Who knows, we get lucky sometimes.
Correct, the steering wheel needs to be removed. The center hub is removed and there is a single cap screw that holds the steering wheel in position. It's usually torqued to a fairly high level, so the assistance of a 2 x 4 for counter torque makes it fairly easy in conjunction with a 15" breaker bar.

There is no easy access for contact cleaner............and, you don't know the problem is with the combination switch. It could be the headlight switch.
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  #12  
Old 12-17-2011, 08:23 PM
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OK today I found that I only have bright lights no matter what I do. I unplugged the position switch but could not tell anything with that. My position switch is operating the signal lights, but moving the lever back and forth does not change anything. I was gone most of the day and I am trying to figure out if I can somehow change the wires around to make the low beams work untill I have time to pull the position switch out. I could drive the car with low beam lights but cannot drive it with high beams on. I have the wiring diagram for the light switch bit not the position switch. Has any one done this before to get by for a while?
Thanks Jack
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  #13  
Old 12-17-2011, 09:07 PM
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What's a "position switch"?
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  #14  
Old 12-17-2011, 10:24 PM
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Sorry it is my combination switch. Excuse the verbage. Remember I am from South Carolina. Have you changed the wiring before to get low beam instead of high beam? Another thought is could I switch the wires on the headlight to get me by for a while? Thanks

Jack
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  #15  
Old 12-17-2011, 10:56 PM
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Probably the easiest way to rig it would be to swap the wires on the back of the fuse holders. Disconnect the battery, remove the screws to hold the fuse rack and lift for access to the backside. The wire color codes TO THE HEADLIGHTS are HI-BEAM.... WHITE RH ..... WHITE/BLK LH and LOW-BEAM.....YELLOW RH.......YELLOW/BLACK LH

The easiest way to swap it temporarily is on the feeder side, coming from the combination switch, which is swapping the WHITE and YELLOW wires.

Trying to swap at connectors involves the high risk of breaking a connector and a host of other problems.

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84 300SD 350K+ miles ( Blue Belle )
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