Melted Ground Wires & Fuse Nº 4 problem

[EuroE9]

One strange thing is that, out of this options: main lights of the car, warning switch, and clock, interior light and trunk light, two things are not working...... The clock and the trunk light, I asume the clock isn´t probable working for two reasons, the fuse inside or the age.... but the trunk light and also the engine light are nor working...

I believe this two white wires (full white and white green) are coming from the radio speakers at the front because under de heater ventilation I did found (I believe) the other end...

So that lives me with only two lights that are not working, the trunk and the engine lights, it could be the switch? but these switcxhes look very simple and difficult to fail.... it looks like just a ground conector...

 

[eriknetherlands]

i think you are right that the white wires are for speakers. Notice how the ends are also dipped in solder, it makes it easy to lock them in a wire clamp.

The trunk light should function as you expect (if circuit fuse is still OK); try bypassing the switch to see if it then works.

The clock could indeed very likely be dead because of a dead internal fuse; that is often the case with the older type clocks. To check if it is the clock or something else, you could measure if you get 12 V on the connector of the clock, but removing the clock is quite some work.

 

[EuroE9]

My plan is to disassembly the clock and change the fuse, and get it to work... How do I bypass the switch, yesterday I tried with the engine light by disconnecting the switch and touching with the brash conector directly to the body but nothing happend... Is this the way to bypass it?

The fuse 4 (8 amp) is ok, Just changed it after this morning drive arround, so the fuse is not the reason for the trunk light not working so I will concentrate in getting this light to work because is the one of fuse 4 circuit beside the clock does not work.

 

[Arde]

considering what the fuse number 4 protects, i can not see it related to the main lights of the car, it goes to the warning switch, and clock, and also interior light and trunk light

could you check if it has been used in a different way adding some other loads on it ?

it is suposed to be used for optional extra trailer indicators, but i assume that not in your case

Agree.
There are too many weird things going on.
1) Motion vs. no motion - IMHO the alternator produces full voltage at relatively low revs, so the car slightly above idle should blow the fuse even without motion if it was related to voltage regulation.

2) Main lights - With original wiring these are not on fuse #4. The only explanation is that the wiring was modified and additional loads added on fuse #4, therefore the need to increase to 25A.

3) Quality of grounds - Seems like a red herring. Imagine the ground path is compromised. That means that a load would take a less than optimal (ie higher resistance) path to ground. Higher resistance would reduce the current on the circuit, therefore reducing the chances of a blown fuse. Yes, the circuit may malfunction due to the voltage drop (AKA ground bounce), or more heat would develop on the ground path, but there is no way this causes more heat on the fuse whose (almost zero) resistance has not changed.

Simple tests:

a) remove fuse #4 and see if the main lights work. If they do not work then the wiring was modified.

b) remove fuse #4 and see if the car starts, if it does not then the wiring was modified to include the ignition on fuse #4.

Now it is a matter of knowing what wiring you have. It is possible the other loads were placed right at the fuse (by moving them from another fuse somehow), or that they were forked downstream of the fuse. In the latter case you disconnect all fuse #4 loads and start reconnecting them one at a time.

 

[EuroE9]

Hello Arde, thanks for helping...

If fuse 4 is removed the dies completely, no lights, no ignition or lights in instrument panel, no click of load shedding relay.

But my question now is..... If this has been change, who the hell change this and why...?

And most important, how should I proceed now?.

This a picture of the fuse box...

 

[deQuincey]

Hello Arde, thanks for helping...

If fuse 4 is removed the dies completely, no lights, no ignition or lights in instrument panel, no click of load shedding relay.

But my question now is..... If this has been change, who the hell change this and why...?

And most important, how should I proceed now?.

This a picture of the fuse box...

View attachment 138098View attachment 138099View attachment 138100 View attachment 138102

i asked you a question and i think it was not responded, is it a CS or a CSA ? AKA automatic ?

from your pictures it seems that number 4 is crowded,

you might want to remove the 2 front screws and look at what is connected behind

in principle, i would be cautious, the diagram that you showed us is different from the one i have in the blue books, and it has more things hanging on that fuse #4

 

[dang]

Have you disconnected the trunk light wires and tested? Then disconnect the interior light and test, and so on. My E3 had burnt wires clustered together and it ended up being the trunk light switch. Eliminate one at a time.

 

[EuroE9]

Ok, here is what I´ve found... to fuse 4 comes:

INPUT Top side: One Red wire (probably 1.0 cross-section)
INPUT Middle side: One Red wire (probably 2,5 cross-section)
OUTPUT Bottom side: Three Red/White wires, maybe one thicker than the other two (0,75, 075,(0,75?) )

According to the Owners Handbook:

69 - INPUT Top side: One Red wire = Main light switch 30
30 - Back Middle side: One Red wire = Battery +
78, 79, 80 - OUTPUT Bottom side: Three Red/White wires = Interior Light, Luggage compartment Light and Clock

All wires seems to be correct and in the right places....

The deeper that I get the more non sense that everything gets......

I am feeling a bit lost to be honest...

 

[EuroE9]

i asked you a question and i think it was not responded, is it a CS or a CSA ? AKA automatic ?

from your pictures it seems that number 4 is crowded,

you might want to remove the 2 front screws and look at what is connected behind

in principle, i would be cautious, the diagram that you showed us is different from the one i have in the blue books, and it has more things hanging on that fuse #4

View attachment 138103

Sorry guys,

The car a BMW 2800 CS Manual 4 ZF gear box

 

[EuroE9]

Have you disconnected the trunk light wires and tested? Then disconnect the interior light and test, and so on. My E3 had burnt wires clustered together and it ended up being the trunk light switch. Eliminate one at a time.

The trunk light is disconnected but I do not know how to bypass the switch...

Yesterday I tried with the engine light by disconnecting the switch and touching with the brash conector directly to the body but nothing happend... Is this the way to bypass it?

 

[deQuincey]

The trunk light is disconnected but I do not know how to bypass the switch...

Yesterday I tried with the engine light by disconnecting the switch and touching with the brash conector directly to the body but nothing happend... Is this the way to bypass it?

the light will receive a white/red cable that brings +12v
the switch simply touches ground
here the schematics:

 

[deQuincey]

BTW



the engine compartment light goes to fuse #1

 

[deQuincey]

Ok, here is what I´ve found... to fuse 4 comes:

INPUT Top side: One Red wire (probably 1.0 cross-section)
INPUT Middle side: One Red wire (probably 2,5 cross-section)
OUTPUT Bottom side: Three Red/White wires, maybe one thicker than the other two (0,75, 075,(0,75?) )

View attachment 138107


According to the Owners Handbook:

69 - INPUT Top side: One Red wire = Main light switch 30
30 - Back Middle side: One Red wire = Battery +
78, 79, 80 - OUTPUT Bottom side: Three Red/White wires = Interior Light, Luggage compartment Light and Clock


View attachment 138108


View attachment 138109


All wires seems to be correct and in the right places....

The deeper that I get the more non sense that everything gets......

I am feeling a bit lost to be honest...

correct:

but main light switch is INPUT, and is directly connected by INPUT to 33 that comes from BATT

 

[deQuincey]

just curious as saw this picture...naked sheet metal...

in my car this is covered by a panel upholstered in elephant skin; was the 2800 a different thing ?

 

[EuroE9]

correct:

View attachment 138118

but main light switch is INPUT, and is directly connected by INPUT to 33 that comes from BATT

Correct, in my fuse box the main light goes to input, top part of the back of fuse 4...

BTW, luggage light works, bulb was dead, but engine light does not work, but does not care because as you said, engine light is for fuse 1, I will check in the future... But main thing is that all lights from fuse 4 works.. Now I don´t know what else to look for...

 

[EuroE9]

just curious as saw this picture...naked sheet metal...

View attachment 138123


in my car this is covered by a panel upholstered in elephant skin; was the 2800 a different thing ?

not a all, is because this piece was the only one without elephant skin fake leather, this piece was a plastic hard board with the elephant skin printed (colour and texture) and I have not had the time to reproduce it yet, the rest of the trunk is finished, following your instructions, of course...

 

[dang]

Questions for you...

1) Have you replaced all the bad wires? I see that you replaced the ground wires, correct? Did you make sure the wires that were next to and twisted around the ground wires are separated and look okay?

2) Have you tried removing the grounds or the power connections from the components you've identified?

3) When you say it blows the fuse only after driving the car, does that mean as soon as you start moving without doing anything else like hitting the brakes, touching any electrical component, etc? Can you recreate the failure every time exactly the same?

4) Since it only does it while "moving" I think you'll have to figure it out by process of elimination. Disconnect each component that you can until something changes and you get a direction to troubleshoot more. In other words, isolate each circuit as best you can.

 

[EuroE9]

I put the bulb from the engine light compartment in the lugagge compartment and light works...

 

[EuroE9]

Questions for you...

1) Have you replaced all the bad wires? I see that you replaced the ground wires, correct? Did you make sure the wires that were next to and twisted around the ground wires are separated and look okay?

2) Have you tried removing the grounds or the power connections from the components you've identified?

3) When you say it blows the fuse only after driving the car, does that mean as soon as you start moving without doing anything else like hitting the brakes, touching any electrical component, etc? Can you recreate the failure every time exactly the same?

4) Since it only does it while "moving" I think you'll have to figure it out by process of elimination. Disconnect each component that you can until something changes and you get a direction to troubleshoot more. In other words, isolate each circuit as best you can.

1) I did replace all ground wires as shown and identify the cables close to them and isolate the with heat shrink sleeve.

2) All ground were chain connected (replaced) and examinate the rest of the connections of each component.

3) When you driving without short light and put them on, in less than 5 seconds fuse blows, with the lights in position 1 (side lights) no problem, but as soon as I put position 2 (headlights) after few meters ahead fuse blows.

Could be possible the the switch light is the problem...? It happend when using this switch and it is connected directly to fuse 4...

 

[dang]

Does the fuse blow if you turn the headlights to position 2 without the motor running?