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How can i find the reason for no power (12v) to fuse number 2 in fuse box
1992 Mercedes-Benz 400E

How can i find the reason for no power (12v) to fuse number 2 in fuse box

(1992 Mercedes-Benz 400E)
this causes no power to fuses 1, a, g, and h so my power windows, sliding roof, wipers don't work.
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2 answers & 1 comment
Popular Answer
on April 13, 2017
Hello,
Check both sides of the fuse, and identify what that fuse is for (owners manual, repair manual, or diagram under lid).

If power goes to the fuse, but not across it, bad fuse. If power goes to the fuse box, bot not to either side of the fuse, bad connection.

Find out what that fuse is for, and let me know. I'll try to keep you from chasing wires all day.
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on April 14, 2017
fuse 2 should come on when key is in on position but does not. It supposed to allow power to fuses 1, a g, h for power window, wiper, sunroof operation. None of these accessories work I have swapped relay for power windows with relay for power seats (same 6 pin relay) but still do not get power to fuse 2. Have also tried 3 different comfort modules plus original and still nothing. I pulled all window switches except rear door and sunroof to check voltage in switch connectors but really do not know what I am looking for. I also checked power on comfort module and got power on 1 pin of the 6 pin connector, but, again, I do not know what I am looking for. I have a circuit tester and a multimeter but am truly a novice with the multimeter. Do all the power window switches have to be installed for any window to operate and get 12v to fuse 2? I believe that if I can find reason for no power to fuse 2, everything will start working. By the way, window motors work with direct power from battery.
How can I check power to fuse block for fuse 2 and what is wiring routed through for fuse 2. by the way, fuse 9 gets 12v
Additional info. Disregard some of previous info above
If I remove fuse 2 and with key in on position, I touch bottom contact the circuit tester lights up and I get a tone which means I have 12v. if I keep circuit tester point in bottom contact and I touch top contact, circuit tester goes very dim and I get no tone from circuit tester.
In my research, I found info to check fuse 2 in on position. I did not check with car running.
I did this test with comfort module installed and also with comfort module removed.
In my limited knowledge, this could indicate a short somewhere, If this is the case, how do I track down the short.
General Diagnosis
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on April 13, 2017
Hello,
Check both sides of the fuse, and identify what that fuse is for (owners manual, repair manual, or diagram under lid).

If power goes to the fuse, but not across it, bad fuse. If power goes to the fuse box, bot not to either side of the fuse, bad connection.

Find out what that fuse is for, and let me know. I'll try to keep you from chasing wires all day.
Sign in to reply
on April 14, 2017
fuse 2 should come on when key is in on position but does not. It supposed to allow power to fuses 1, a g, h for power window, wiper, sunroof operation. None of these accessories work I have swapped relay for power windows with relay for power seats (same 6 pin relay) but still do not get power to fuse 2. Have also tried 3 different comfort modules plus original and still nothing. I pulled all window switches except rear door and sunroof to check voltage in switch connectors but really do not know what I am looking for. I also checked power on comfort module and got power on 1 pin of the 6 pin connector, but, again, I do not know what I am looking for. I have a circuit tester and a multimeter but am truly a novice with the multimeter. Do all the power window switches have to be installed for any window to operate and get 12v to fuse 2? I believe that if I can find reason for no power to fuse 2, everything will start working. By the way, window motors work with direct power from battery.
How can I check power to fuse block for fuse 2 and what is wiring routed through for fuse 2. by the way, fuse 9 gets 12v
Additional info. Disregard some of previous info above
If I remove fuse 2 and with key in on position, I touch bottom contact the circuit tester lights up and I get a tone which means I have 12v. if I keep circuit tester point in bottom contact and I touch top contact, circuit tester goes very dim and I get no tone from circuit tester.
In my research, I found info to check fuse 2 in on position. I did not check with car running.
I did this test with comfort module installed and also with comfort module removed.
In my limited knowledge, this could indicate a short somewhere, If this is the case, how do I track down the short.
on April 13, 2017
Turn ignition switch to the 'on' position!
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