Author Topic: Fuse Block upper and lower wire connection  (Read 1615 times)


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Fuse Block upper and lower wire connection
« on: June 28, 2023, 14:46:57 »
Fuse block cover has a fuse location description that states front and back. Does that mean upper and lower wire connection on the back of the block?
1970 280SL/8 W113 101624 miles.
1950 MG-TD
2021 Harley Davidson CVO Trike


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Re: Fuse Block upper and lower wire connection
« Reply #1 on: June 29, 2023, 10:55:56 »
Dear Mr. Henderson

The main fuse box has a total of 12 circuits.  If your block has still the identification it would be easier to know where do the fuse no.1 is.

If it is not the case, the fuse 1 is the only that is not interconnected to any other circuit since it is intended only for the small loads that are energized all the time.  I mean T30 clients.

As a general rule any circuit that has energy all the time will use cables in red base colour with any variation of stripes on it to trace easily the clients.

The fuse box has for each circuit an input and output post.  The input side is the one that has the lesser screws and that is slightly in a lower in height position.  The output side is the one that has for every fuse one screw and that is slightly raised.

You begin reconnecting the cables to the fuse box by screwing in first all the thicker cables that go on the input side. 

1. Connect the yellow thick cable on port 11, input side (lower)
2. Connect the white thick cable on port 9, input side
3. Connect the gray thicker cable on port 7, input
4. Then you go for the feed for all T15 circuits, which is connected to port 2 input.  This time is not a single cable, is a set of cables that has at least one thick red/black stripes cables main T15, one thinner red/black cable for the coil resistance, and finally one blue/red cable.
5. Connect the only red single cable that is on the harness that comes from the main light switch, that feeds all T30 customers.

I know that your harness is a REPRO, and colours may not match, that is why we have to mention each time where do that cable goes afterwards so that you check with a
Multimeter after the continuity to that particular accessory/client

Then once all cables connected on the input side you will proceed to the output side customers.

Start with the easiest to reduce the clutter on your workspace.

1. Circuits 12 & 11

Begin with yellow cables. These are the easiest, connect the yellow/black to 12, and the solid yellow to 11

2. Circuits 10 & 09

Connect the double white terminals.  There should be one white/black + white/violet (multifunction steering column switch terminal), that goes on circuit 10.  If the colours do not match exactly, take a multimeter and find to which headlight H4 connector this has continuity. It should be the LEFT H4 connector.

Circuit 09, has also two white/something cables. Originally was solid white+white/blue (12 pin connector for instrument cluster).  This can be identified by making a continuity test to the RIGHT HEADLIGHT H4 terminal

3. Circuits 08 & 07

This serve all T58 customers. He cables should be gray.  There should be two sets of terminals with three cables each, in different combinations of gray colours.

Circuit 8, 1x terminal with 3x gray cables.  Originally they are 2x gray/black + 1 gray/yellow/green serving this last one terminal “N” on main light switch bunch of cables.   So find out which set of gray cables (containing 3 leads) makes continuity to any terminal at the main light switch

Circuit 07. It has another terminal with 3x gray cables. Originally it was 2x gray/red + 1x gray/violet (serving the main cluster dimmer terminal).  On this case it’s easier confirm that this terminal has continuity to any of the pins in the 12 pin connector that serves the main central instrument panel.

Circuit 06.  This one receives only two cables. They were originally 2x black/red thick. They serve the heater  switch (05 on pagoda wiring diagram), and the cold start relay (21).  I am looking at the 230SL diagram right now.  So take your multimeter and make again continuity test to any of the mentioned customers connectors.

Circuit 05. This has many customers, let’s do it at the end.

Circuit 04. Fuel pump. Easy should be a thick cable, originally black/white/rose. You could have any colour as is not original, but make again the continuity test towards the 12 pin connector that is the bridge to the rear wiring harness.  The fuel pump terminal is on pin no.2, one at the top of that connector.  The botton of each connector is where all the cables enter to it.

For your reference I have attached a Mercedes manual that pinpoints the position of each terminal inside a connector.  That will be your best reference to solve this puzzle.

Circuit 03. This one is empty, unless your car has automatic transmission, in which case this port will feed the kickdown switch, and the IDDLE switch at the intake manifold.  The cables for those two are black/something. Not very thick. The only way to sort it out will be with the multimeter and checking continuity towards those accessories terminals.  The kickdown terminal is inside the cabin branches, it derives right after the entry to cabin and is on the same branch that connects to your foot operated high beam/low beam headlight switch.

Circuit 02. Also leave for later, a lot of cables.

Circuit 01. This is the easiest. Connect there all the red/something cables.

As you see you need to perform a lot of continuity test towards the particular customer/accessory that each circuit is supposed to serve in order to find out where the cables should be connected.

Have patience, and be systematic.  Happy Sherlock activities….

Look at document attached, will be of great help. Removed by admin because of copyright violations.

Best regards
Eng. Leonardo Peterssen
« Last Edit: June 29, 2023, 11:00:13 by Peter van Es »

Peter van Es

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Re: Fuse Block upper and lower wire connection
« Reply #2 on: June 29, 2023, 10:59:13 »
Attached document removed because of copyright restrictions.
A copyright free version is available here:
1970 280SL. System Admin of the site. Please do not mail or PM me questions on Pagoda's... I'm not likely to know the answer.  Please post on the forum instead!


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Re: Fuse Block upper and lower wire connection
« Reply #3 on: June 29, 2023, 11:12:55 »
Thank you