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1989 560SEL
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are you sure? i thought the clock drew its power from the battery at all times, whether or not the car was running [?]
 

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1987 420 SEL
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2,090 Posts
My clock maintains the current time whether the car is running or shut off. It must be something that is shutting down when you turn off your ignition.
 

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1991 500SEC sub 50K mi. 1987 560SEC Now 150K mi. 2018
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Hi Michael,

That's a strange one. Here's the clock circuit diagram to assist possible diagnosis.

Has this been a consistent issue with the car, or something that has appeared fairly recently?

MBL
 

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1989 560SEL
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many people have broken clocks in their cars, but this is the first i've heard that there seems to be a connection with having the ignition on or off. i still think another possibility is that the clock works intermittently or is running slow whether or not the ignition is on. if that's the case, it could be as simple as either dirt or oxidation slowing down the arms of the clock, or it could be a loose contact or fuse somewhere.

have you tried marking down the exact time when you get out of your car in the evening, and checking it against the time it shows the next AM? or when going on an extended trip (3-5 hrs minimum), doing the same thing?
 

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1991 300 SE
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18,534 Posts
Michael Pillay - 4/6/2005 7:23 AM

I noticed the clock in my car only runs when the car is turned on. Anyone else have this problem? How can I fix this?

If the clock keeps correct time when the car is running – 15 minutes have elapsed when you take a 15 minute drive – then the clock and fuse are fine and at some point in the past someone wired the clock wrong. Do you have the original radio? Does your power antenna work? The radio and the clock are on the same circuit (fuse 13) and if an upgrade or repair was done to the radio or antenna, then the clock power wire, which should be always live, was somehow connected to the switched power wire connected to the ignition for the radio to go on and off with the car. The clock wire is blue, if memory serves, and you may need to find a live feed from a wire behind the dash such as the radio memory presets or run an inline fused wire to the battery through the firewall.

All three of my clocks work, btw…
[:)]
 

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1991 500SEC sub 50K mi. 1987 560SEC Now 150K mi. 2018
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Hi jdc1244a,

This post brings up some really good points & raises good questions too. Not meaning to split hairs here jdc, but there is one small detail that might confuse diagnosis: that is the fact that from '86 up, MB used different fusebox wiring than previous model years '83-'85. Doesn't fuse #2 feed the clock and radio for the later cars? Refer below images pls.

I wonder what function does the NPN transistor serve in the circuit between the clock & tachometer (as shown in the circuit detail posted yesterday)?

Hi Michael, Has any work been done to the car that could have affected the electrics? Is the fuse HOT with the ignition shut off?
Should (obviously) be.

Puzzled in Concord, [?] MBL
 

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500SE AMG, E350 4matic, GL 450
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Discussion Starter #13
No electrical work has been done since I bought it unless you count the installation of the power antenna. It seems like the clock was that before anyway. I am not sure about the fuses. I probably wont pop the hood until Saturday. As soon as I check, I'll post.
 

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1991 500SEC sub 50K mi. 1987 560SEC Now 150K mi. 2018
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Hi Michael,

Yes, the antenna install wouldn't affect the clock, I shouldn't think.

Trick is to find out if that fuse looses power when the ignition is shut off. If other components linked to the fuse work with the key OFF - the fuse is (obviously) powered. These items would include 4 way flashers, power seats*, interior lamps, etc. If they work as expected, it would follow that the problem would appear to be downstream of the fuse, somewhere between the fusebox & the instrument cluster > clock connections.

From what you describe, it almost sounds as though the clock feed (somehow?) is connected to the wrong fuse - one that is powered only when the ignition is ON..... screwy.

Regards, MBL

*Just looking at the MY 1989 Late production Power Seat schematic, fuse 2 feeds one of the connectors on K6 Power Seat Control Relay, for instance.
 

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1991 300 SE
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MBL87560SEC - 4/7/2005 12:01 PM

Doesn't fuse #2 feed the clock and radio for the later cars?

Correct – I was thinking of the first gen cars and the thread author has a second gen. If the person who repaired the antenna was not careful he could have attached the clock lead to a switched circuit by mistake. Again, if the clock keeps correct time when the car is running, it would not hurt to pull the radio and check how things are wired.
 

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500SE AMG, E350 4matic, GL 450
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Discussion Starter #16
Well I paid a little more attention this morning to the clock. I set it before I left home andchecked it when I got to work. The car clock showed about 3 minutes had elapsed, when in fact it had been 20 minutes. I think.....the thing is that the needle did not move much at at all. I still have to check the fuses....tomorrow hopefully I will have time.[:)]
 

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1991 500SEC sub 50K mi. 1987 560SEC Now 150K mi. 2018
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Hi Michael,

This Instrument Cluster Repair article looks to be very good, and may be of some help in your case too. It seems there are a couple of capacitors that routinely fail in the W126 clock. I think it might be considered a possibility worth looking at - in light of the clock's stated accuracy this morning.

For some reason I've been unable post a direct link, so here is the convoluted way....

Go to http://instrument.articles.*/renew/ (see below note)

* Annoying as hell, but substitute m b z .org(no spaces) for the ataskerisk in your web browser address field. I think benzworld locks out a direct link to mbz while posting....[:(]

Cheers, MBL
 
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