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R32VWBeetle
Samba Member
Joined: July 21, 2012
Posts: 123
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 Posted: Fri Aug 24, 2012 11:40 pm Post subject: 1970 beetle Dimmer Relay Problem |
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| I need some input, while I was driving at night, I started to smell a burnt smell, after I pull over and took out my flash light I saw the smoke coming from the Dimmer Relay (J in Bentley Manuel), 56a wire and connector were burning up, the wire was really hot and the plug connector insulation was melting, 56, F and S all Seem Fine, what would cause the 56a connection to malfunction? also the dimmer Relay was really hot, what should I check for? Did the relay turn bad? Thanks. |
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glutamodo 
The Android
Joined: July 13, 2004
Posts: 26627
Location: Douglas, WY
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| Posted: Sat Aug 25, 2012 11:42 am Post subject: |
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The power runs into the relay on terminal 56. 56a runs from the relay to the fusebox to power the low beams. Anything that should make that wire get hot enough to melt should have blown a fuse before that happened. However, if the relay itself malfunctioned, it should have melted the white/black 56 wire and not the yellow output line, unless the "hot spot" inside the relay was right at that wire. That leads to this question - was it just where that yellow 56 wire plugged into the relay that got hot, or was the whole wire hot from there to the fusebox? Oh, and how dim did your headlights get whilst this was happening?
Did you check that no stray wires or metallic objects happened to connect (short out) the feed side of fuse 5 and 6 at the fusebox? Also, are you using the correct white 8 amp fuses?
-Andy |
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R32VWBeetle
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Joined: July 21, 2012
Posts: 123
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| Posted: Sat Aug 25, 2012 3:18 pm Post subject: |
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| glutamodo wrote: |
The power runs into the relay on terminal 56. 56a runs from the relay to the fusebox to power the low beams. Anything that should make that wire get hot enough to melt should have blown a fuse before that happened. However, if the relay itself malfunctioned, it should have melted the white/black 56 wire and not the yellow output line, unless the "hot spot" inside the relay was right at that wire. That leads to this question - was it just where that yellow 56 wire plugged into the relay that got hot, or was the whole wire hot from there to the fusebox? Oh, and how dim did your headlights get whilst this was happening?
Did you check that no stray wires or metallic objects happened to connect (short out) the feed side of fuse 5 and 6 at the fusebox? Also, are you using the correct white 8 amp fuses?
-Andy |
the white/black 56 wire never melted, the hot spot was where the yellow 56a wire connects to the dimmer relay, but the whole wire was hot, the hot spot was not at the fuse box connection, also it didn't blow any fuses all the fuses for the lights are the white ceramic 8 amp fuses, and also my lights never got dimmed, I checked all the wires they seem fine, but this morning I did test out the relay again, when I turn on the high beams, the relay is cool, not hot but as soon as I turn the low beams it starts smoking and burning right at the relay? |
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glutamodo
The Android
Joined: July 13, 2004
Posts: 26627
Location: Douglas, WY
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| Posted: Sat Aug 25, 2012 3:48 pm Post subject: |
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Hmm, well the relay is not grounded - the casing does not play any part in the circuit, it only gets power from 56 and the S terminal is the ground that energizes the relay to toggle to the other position. So it shouldn't overheat.
If you've ever looked inside a headlight relay, at least the 311941583A 4-terminal ones, they are extremely simple. Just a large electromagnet and a set of high-amp single-pole, double throw togging points and one resistor. The electromagnet should have zero power going through it unless the S terminal is engaged. Now, if the contacts were gunked up and there is resistance as a result, I guess that could cause some heating. I guess if the rivet where the 56a tab connects to the point contact, if that was loose or corroded, that might do it too. Usually though, they are in good shape.
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R32VWBeetle
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Joined: July 21, 2012
Posts: 123
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| Posted: Sat Aug 25, 2012 8:04 pm Post subject: |
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| glutamodo wrote: |
Hmm, well the relay is not grounded - the casing does not play any part in the circuit, it only gets power from 56 and the S terminal is the ground that energizes the relay to toggle to the other position. So it shouldn't overheat.
If you've ever looked inside a headlight relay, at least the 311941583A 4-terminal ones, they are extremely simple. Just a large electromagnet and a set of high-amp single-pole, double throw togging points and one resistor. The electromagnet should have zero power going through it unless the S terminal is engaged. Now, if the contacts were gunked up and there is resistance as a result, I guess that could cause some heating. I guess if the rivet where the 56a tab connects to the point contact, if that was loose or corroded, that might do it too. Usually though, they are in good shape.
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I did notice one thing though, the wires are not the correct gauge, they are not as thick as the Manuel states, would that be a problem? (some po work has been done on the wiring before I had car) also when I followed the black and white cable from the relay to the headlight switch I did notice that the wire was on 57 not 56, I wonder if that could also have cause it? but when I connected to the correct number I still saw a bit of smoke coming out, maybe I need to put the correct gauge wire on it? i did notice that the black and white wire was a bit warm |
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glutamodo
The Android
Joined: July 13, 2004
Posts: 26627
Location: Douglas, WY
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| Posted: Sat Aug 25, 2012 8:31 pm Post subject: |
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| Terminal 57 stopped being used on VW bugs for 1968, it's for parking lights, it only comes on when you have power to the middle position of the headlight switch. Are you sure that it was on that terminal? |
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