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1999 ML 430
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Discussion Starter · #1 ·
About 6 months ago, my factory Bose radio just went out when I hit a pothole. After finally acquiring the radio removal tools I pulled the radio today. I saw that the 3 amp fuse on the radio was blown. As I was inserting a new fuse, it blew right away (truck was not running). What could be causing the new fuse to blow immediately?
 

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94 S420 RIP 2/8/13 02 ML55AMG, 06 CLS55AMG, 89 Mas. 228, 84 Por. 911 Carrera, 93 Toyota t.t. Supra
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It would appear to me that there is a direct power short. Understand that there are two power wires that service the unit. One actually turns the unit off and on. But the other is in place to keep the tuner settings and other pre-sets from disappearing when you turn the unit off. Would suggest you run the wires and look for the short with a light or meter.
 

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Discussion Starter · #4 ·
Update...so I fixed the short and the radio is now working. When the radio is on and I turn off the ignition, the radio remains powered on. How do I get the radio to power off when I turn off the ignition, and then power back on when I re-start the truck (without having to manually push the power button to power up the radio)?
 

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Update...so I fixed the short and the radio is now working. When the radio is on and I turn off the ignition, the radio remains powered on. How do I get the radio to power off when I turn off the ignition, and then power back on when I re-start the truck (without having to manually push the power button to power up the radio)?
It would be nice if you told us what the short was. Also recheck fuse #10.
 

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Update...so I fixed the short and the radio is now working. When the radio is on and I turn off the ignition, the radio remains powered on. How do I get the radio to power off when I turn off the ignition, and then power back on when I re-start the truck (without having to manually push the power button to power up the radio)?
Agree with 43sqd. Blown fuse 10 will cause radio to remain on when the ignition is off. But radio will still be usable manually via the power button because it has two power sources; direct and ignition. If fuse 10 is keep blowing, you haven't cleared the short yet.
 

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1999 ML 430
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Discussion Starter · #7 ·
Sure, no problem.

Fuse number 10 is not blown, it's still intact.

The short was caused by a nickel that my daughter had shoved into the tape player. When the truck went over the pothole, the nickel slid off the top of the internal part of the radio and wedged inself onto the electronics board. As soon as I removed the nickel, replaced the fuse on the back of the radio and powered it up the radio worked.
 

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1999 ML 430
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Discussion Starter · #9 ·
JAD, with key in hand, check fuse #10 with a test light. There should be no voltage.
43sqd-

I don't fool with electronics much... but it sounds like I am to pull fuse number 10, take the wires from the test light and insert into fuse #10's spot. If the light comes on, that's bad because that indicates voltage.

JAD
 

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43sqd-

I don't fool with electronics much... but it sounds like I am to pull fuse number 10, take the wires from the test light and insert into fuse #10's spot. If the light comes on, that's bad because that indicates voltage.

JAD
No JAD, leave the fuse where it is. Connect the alligator clip of the test light to the neg. battery end and then with the test light, probe tboth contacts of the fuse.
 

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43sqd-

I don't fool with electronics much... but it sounds like I am to pull fuse number 10, take the wires from the test light and insert into fuse #10's spot. If the light comes on, that's bad because that indicates voltage.

JAD
A non-electrician way to check is to look at other devices on Fuse 10. The list of devices is underside of the cover of the fuse box in the engine compartment. For example in 2002, Fuse 10 list includes radio, glovebox light, emergency system, etc. The list can be different in 1999.
 

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Discussion Starter · #14 ·
A non-electrician way to check is to look at other devices on Fuse 10. The list of devices is underside of the cover of the fuse box in the engine compartment. For example in 2002, Fuse 10 list includes radio, glovebox light, emergency system, etc. The list can be different in 1999.
On the 1999 it is (including the radio) the vanity mirror, glovebox light and cigarette lighter. All worked with the key turned, none of them worked without the key in the ignition.
 

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On the 1999 it is (including the radio) the vanity mirror, glovebox light and cigarette lighter. All worked with the key turned, none of them worked without the key in the ignition.
There must be something else inside that tape player that is providing power to an unwanted circuit.
 

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Discussion Starter · #18 ·
I'll take the radio out and apart again. I checked it pretty good the first time around and didn't see anything else but I'll double check. I'll check fuse 21 also.

I'll report back with an update.
 
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