Author Topic: Fuse box  (Read 354 times)

TNNBENZ

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Fuse box
« on: 07 December 2021, 12:15 PM »
     Inside my fuse box there is much white powered corrosion and faded fuses.  One 16a fuse was stuck or melted  to one of the terminals. Also the 3 relays look very faded and old.
I watched a video on how to test a relay but was tired & did not understand it very well.  I bought a spare relay months ago.  What part number is correct for a URO relay for my SEL ?
     I will find my new one and compare number later. Do I need to test the relays before I attempt to start the car ?  I assume a relay is involved with the ignition ?????
Neglected ~ Rescued ~ 1977 450SEL 4.5L  U.S.A. ver.
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raueda1

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Re: Fuse box
« Reply #1 on: 07 December 2021, 12:20 PM »
I'd replace the relays on principle.  They're easily available and aren't expensive.  As far as fuses go, just replace them all too.  Whey worry about it?  Also cheap.  Use a metal brush to clean off the crap of the contacts and you should be good to go.  Cheers,
-Dave
Now:  '76 6.9 Euro
Before that:  1966 230S, 1964 220SE coupe, 1977 Carrera 3.0

TNNBENZ

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Re: Fuse box
« Reply #2 on: 07 December 2021, 12:47 PM »
I'd replace the relays on principle.  They're easily available and aren't expensive.  As far as fuses go, just replace them all too.  Whey worry about it?  Also cheap.  Use a metal brush to clean off the crap of the contacts and you should be good to go.  Cheers,
     raueda1 you are 100% correct !!!  I need to save all I can save is why I do not want to buy any relays if not needed,  my finances are getting low for this project.  I have another important project going on now also,  a 70's pick-up  ::)   :D    :)  Pick up is 97% done for now, just another day or two...........or 3 ............or 4.............ha.   
     I want to here the Merc run, and then will start to replenish my $$$ reserves again to spend on the Merc !!!
Neglected ~ Rescued ~ 1977 450SEL 4.5L  U.S.A. ver.
Project of Compassion ~ Respect
Silver Green Metallic / Toast
Left Hand Drive
Sliding Roof

TNNBENZ

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Re: Fuse box
« Reply #3 on: 07 December 2021, 02:12 PM »
     URO' P/n # 0015420219  Relay.    This is multipurpose relay.  Are there 3 of these in my fuse box ?  Weather hinders me from looking under hood at the moment !!! ::)
More importantly, do any of the 3 relays in fuse box pertain to starting & engine running ???  Also any instructions to testing the 3 relays..........will be greatly appreciated !!!!!!!
Neglected ~ Rescued ~ 1977 450SEL 4.5L  U.S.A. ver.
Project of Compassion ~ Respect
Silver Green Metallic / Toast
Left Hand Drive
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rumb

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Re: Fuse box
« Reply #4 on: 07 December 2021, 04:52 PM »
One of the relays is for the fuel pump.
Get new copper fuses and replace all of them.
'68 250S, '77 6.9 euro, '91 300SE, '98 SL500 '14 CLS550

TNNBENZ

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Re: Fuse box
« Reply #5 on: 08 December 2021, 12:02 PM »
     Thank-you rumb  :) ...  Good to know 1 relay is needed for fuel pump.  I have 1 spare, if all three are bad.  Pierre says the relays seldom go bad, so I hope mine are ok, but they do look bad.........lol
      I have fuses on my current parts list !!! I was waiting on information about relays before I submitted order.  I do not want to spend a dollar more than neccisary until I hear my engine run as smooth as a sewing machine !!!   ha.......... rumb you have been  very helpful as always ,   & I do THANK-YOU very MUCH...  :)   ;) ;)   :)
Neglected ~ Rescued ~ 1977 450SEL 4.5L  U.S.A. ver.
Project of Compassion ~ Respect
Silver Green Metallic / Toast
Left Hand Drive
Sliding Roof

Jan S

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Re: Fuse box
« Reply #6 on: 08 December 2021, 12:25 PM »
You probably have the "ice cube" relays, right?

I have three of those in the fuse box - one for fuel pump, one for AC/starter and one for cold-start valve.

Under the dash on the passenger side I also had a fuel injection relay (ice cube relay).

You can test the relay, e.g. the fuel pump relay: the hole in the socket that matches pin 30 should deliver 12V. If you connect pin-hole 30 with pin-hole 87 (both in the socket) the fuel pump should run.

The relay itself can be tested by connecting it to the battery 12V: without 12 V there should be connection between pin 30 and pin 87a. With 12 V you should here a "click".

Let us know how it goes.
1975-mod W116 450 SE with 6.9 engine

Jan S

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Re: Fuse box
« Reply #7 on: 08 December 2021, 12:33 PM »
... I forgot to write that pin 85 and 86 are used to connect it to the 12V battery.
1975-mod W116 450 SE with 6.9 engine

TNNBENZ

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Re: Fuse box
« Reply #8 on: 08 December 2021, 05:00 PM »
You probably have the "ice cube" relays, right?

I have three of those in the fuse box - one for fuel pump, one for AC/starter and one for cold-start valve.

Under the dash on the passenger side I also had a fuel injection relay (ice cube relay).

You can test the relay, e.g. the fuel pump relay: the hole in the socket that matches pin 30 should deliver 12V. If you connect pin-hole 30 with pin-hole 87 (both in the socket) the fuel pump should run.

The relay itself can be tested by connecting it to the battery 12V: without 12 V there should be connection between pin 30 and pin 87a. With 12 V you should here a "click".

Let us know how it goes.
     This is from Eeuroparts:  Vehicle Note: For A/C; Windows; Headlight Wiper; Fuel Pump; Auxiliary Fan
Neglected ~ Rescued ~ 1977 450SEL 4.5L  U.S.A. ver.
Project of Compassion ~ Respect
Silver Green Metallic / Toast
Left Hand Drive
Sliding Roof

TNNBENZ

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Re: Fuse box
« Reply #9 on: 08 December 2021, 05:02 PM »
... I forgot to write that pin 85 and 86 are used to connect it to the 12V battery.
     Do you connect 12v to one pin & ground wire to other pin. Does it mater which pin ? 
Are all three relays the same part number ? Also you mention a relay under dash for fuel injection, is that for a 4.5L or your 6.9L or both ???
Neglected ~ Rescued ~ 1977 450SEL 4.5L  U.S.A. ver.
Project of Compassion ~ Respect
Silver Green Metallic / Toast
Left Hand Drive
Sliding Roof

TNNBENZ

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Re: Fuse box
« Reply #10 on: 08 December 2021, 05:07 PM »
     Mercedes Benz price $28.00 American.....Uro' price $18.00 American.........
Neglected ~ Rescued ~ 1977 450SEL 4.5L  U.S.A. ver.
Project of Compassion ~ Respect
Silver Green Metallic / Toast
Left Hand Drive
Sliding Roof

Jan S

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Re: Fuse box
« Reply #11 on: 09 December 2021, 04:57 AM »
... I forgot to write that pin 85 and 86 are used to connect it to the 12V battery.
     Do you connect 12v to one pin & ground wire to other pin. Does it mater which pin ? 
Are all three relays the same part number ? Also you mention a relay under dash for fuel injection, is that for a 4.5L or your 6.9L or both ???

This is for my 1975 US-version 450 SE.

The three ice cube relays in the fuse box (fuel pump, AC/starter, cold-start valve) and the one under the dash (fuel injector relay) are the same. This relay set-up varies depending on type of car and year, I guess. I have a 1975 116.032 US-version with engine M117.983. However, a previous owner replaced the engine with a M100.985 (6.9). But the relays are from the original car.

This diagram is helpful (valid for 1975 M117, both 450 SE/SEL): https://cdn.w116.org/cd/ETM/75SEetm.pdf

On page 8 you see the fuel pump relay. I believe 86 is connected to + and 85 to - (the ECU). It's a bit hard to read. But I believe that is what I did. When you remove/touch the ground (-) on the battery you will here a clicking sound. That means the relay is working as it should.

You see that upstream lies the fuel injector relay. This relay was shot in my car i.e. it did not deliver 12 V to the fuel pump relay.

When spring comes I will replace all my relays. Some of them are probably 46 years old ......
1975-mod W116 450 SE with 6.9 engine

TNNBENZ

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Re: Fuse box
« Reply #12 on: 09 December 2021, 04:17 PM »
     Mercedes Benz price $28.00 American.....Uro' price $18.00 American.........
     Autohausa  Uro' $7.99 American, price varies, AMAZON ETC...
Neglected ~ Rescued ~ 1977 450SEL 4.5L  U.S.A. ver.
Project of Compassion ~ Respect
Silver Green Metallic / Toast
Left Hand Drive
Sliding Roof

TNNBENZ

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Re: Fuse box
« Reply #13 on: 09 December 2021, 04:36 PM »
... I forgot to write that pin 85 and 86 are used to connect it to the 12V battery.
     Do you connect 12v to one pin & ground wire to other pin. Does it mater which pin ? 
Are all three relays the same part number ? Also you mention a relay under dash for fuel injection, is that for a 4.5L or your 6.9L or both ???

This is for my 1975 US-version 450 SE.

The three ice cube relays in the fuse box (fuel pump, AC/starter, cold-start valve) and the one under the dash (fuel injector relay) are the same. This relay set-up varies depending on type of car and year, I guess. I have a 1975 116.032 US-version with engine M117.983. However, a previous owner replaced the engine with a M100.985 (6.9). But the relays are from the original car.

This diagram is helpful (valid for 1975 M117, both 450 SE/SEL): https://cdn.w116.org/cd/ETM/75SEetm.pdf

On page 8 you see the fuel pump relay. I believe 86 is connected to + and 85 to - (the ECU). It's a bit hard to read. But I believe that is what I did. When you remove/touch the ground (-) on the battery you will here a clicking sound. That means the relay is working as it should.

You see that upstream lies the fuel injector relay. This relay was shot in my car i.e. it did not deliver 12 V to the fuel pump relay.

When spring comes I will replace all my relays. Some of them are probably 46 years old ......
     Good to know your 47 year old relays are working !!!  ;)   Several weeks ago I pulled on one of my relays to remove it & check number on it. It was very tight & I was just about to stop for the night so I did not want to take the time to try and remove it carefully so I stopped.   The info on it is hard to read it without taking it out.  Also glad all three are the same so if I have just one bad I have 1 new spare !!! Your diagram gives me reason to look at mine. I have a 1977 diagram. I did not know there was one under the dash.  I may have not ever found it !!!  ha....... ???
     Hopefully when my parts come in I will be able to at least start my cherished beater of a green persuasion.....Then in the Spring, I as well may change my relays also..........Good luck 2 u and best wishes.........I will b following your cooling system thread until then......
Neglected ~ Rescued ~ 1977 450SEL 4.5L  U.S.A. ver.
Project of Compassion ~ Respect
Silver Green Metallic / Toast
Left Hand Drive
Sliding Roof