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R129 ? x 2

Discussion in 'Electrics, Vacuum, Ignition and ECU' started by roblloyd, Jan 20, 2020.

  1. roblloyd

    roblloyd Senior Member

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    Your Mercedes:
    R129 1990 500SL
    Hi
    Can anyone tell me where on the car (1990 500sl) is fuel pump RELAY? The other i need to know is where the oxygen sensor is on the car.
    Thank you for any replys
    Rob
     
  2. LostKiwi

    LostKiwi Senior Member

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    Your Mercedes:
    '93 500SL-32, '01 W210 Estate E240, 02 R230 SL500 (Malcolm Spec), 04 Smart Roadster Coupe
    This is for LHD car. RHD is opposite side:
    2014-03-09 13.32.28.jpg

    Circuit N16.

    O2 sensor (if you have one) will be under the vehicle.
     
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  3. Richard Moakes

    Richard Moakes Senior Member

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    Your Mercedes:
    1991 R129.066 M119.960; 2005 W164.175 M113
    Agreed, N16, also known as the MAS relay, controls the fuel pump

    O2 sensor connects via a bulkhead connector under the car near the exhaust.


    Sent from my iPad using Tapatalk
     
  4. davidsl500

    davidsl500 Senior Member

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    Your Mercedes:
    R172 250CDI, R129 SL500 Gone...
    There is a secondary fuel pump relay in the boot above the battery. You have the MAS in the front but there is definitely one in the boot on the right hand side above the battery. Its normally green. If you apply a 12v+ feed to pin 87 it will kick the pump(s) into action...
     
  5. OP
    roblloyd

    roblloyd Senior Member

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    Your Mercedes:
    R129 1990 500SL
    Its not the first one , mass, because thats to big.
    The error code is 14-2 fuel pump reley (circuit 87) not working.
    Looked on ebay and the relay came back as 001 542 0219 , its silver in color a sort of 1 inch square and has 5 round pins on the bottom and a plastic 1. AS you say pin 87 just like in the code so this must be were you said BUT its finding it. Going to go and have a look BUT if anyone know were in the boot above the battery it is let me know. Say this because there loads of other electric componts there.
    Mine is a 1990 500sl , is there not a oxygen sensor on the top of the engine?
    Thanks for the relays its does help me out and stops others robbing me.
    Rob
     
  6. davidsl500

    davidsl500 Senior Member

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    Your Mercedes:
    R172 250CDI, R129 SL500 Gone...
    This is what my relay looked like. From memory looking in the boot right hand side after taking the liner off, just above the battery. Yes lots of cables and other gear but it stood out for me - note the 30A fuse on top


    relay 1.JPG relay 2.JPG
     
  7. OP
    roblloyd

    roblloyd Senior Member

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    Your Mercedes:
    R129 1990 500SL
    The one i have does not have the 30a fuse on the top but the side veiw has the same numbers at the bottom. Going to go out in a little while and look. Did write down all the relays numbers i could find none came back with 9619 at the end. The one i got was only £12 hopefully it works but knowing my luck its the one you put up.
    Thanks david
    Rob
     
  8. davidsl500

    davidsl500 Senior Member

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    Your Mercedes:
    R172 250CDI, R129 SL500 Gone...
    I think it may just be above the battery positive terminal. I don't have the car anymore so can't check physically!
     
  9. OP
    roblloyd

    roblloyd Senior Member

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    Your Mercedes:
    R129 1990 500SL
    Just looked all around the battery and i cannot find it. part number is 001 542 0219
    What i did do was unscrew the fuse cover in the engine bay and there is a place for relays there, its a black box above the normal fuses. Saw a green one like above part number 126 820 2026 BUT on ebay it says its the headlight cleaning system.There is another bigger relay above that and 2 long black long boxes, 3 inch and about 4 inchs. Wonder if there are relays under these boxes?
    Got the part just do not know where it goes, one of those that do your nut in.
     
  10. SL55 Mark

    SL55 Mark Senior Member

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    Maybe the problem you have is that your relay is missing ?
     
  11. OP
    roblloyd

    roblloyd Senior Member

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    Your Mercedes:
    R129 1990 500SL
    Its not missing been driving the car for 10 years. The code tells you the problem just do not know where the relay is.
    rob
     
  12. LostKiwi

    LostKiwi Senior Member

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    '93 500SL-32, '01 W210 Estate E240, 02 R230 SL500 (Malcolm Spec), 04 Smart Roadster Coupe
    Oxygen sensors live in the exhaust to monitor efficiency of combustion and are usually used in conjunction with catalytic converters. Cats were not compulsory until 1993 so I wouldn't be surprised if you don't have one.
     
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  13. davidsl500

    davidsl500 Senior Member

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    Your Mercedes:
    R172 250CDI, R129 SL500 Gone...
    Found this pic of the fuel pump relay in the boot by the battery. I'm pretty sure non of the relays in the box behind the main fuse box under bonnet have anything to do with the fuel system. This was a 1995 one - maybe the earlier ones are different..

    relay location 1.JPG
     
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  14. OP
    roblloyd

    roblloyd Senior Member

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    Your Mercedes:
    R129 1990 500SL
    Thanks David
    The battery is out of the car so going to have another look around were your photo shows. Thing is mine is a 500sl and they changed thing when the sl500 came out.
    The blink code came up as.
    14 port. Continvous fuel injection system (mass controller).
    14 / 2 code=Fuel pump relay (circuit 87) not working.
    People say its the mass module BUT why would it give the blink code 14 / 2 fuel pump relay if there is not a relay?
    It all started with the ASR light coming on.
    Thanks
    Rob
     
  15. LostKiwi

    LostKiwi Senior Member

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    '93 500SL-32, '01 W210 Estate E240, 02 R230 SL500 (Malcolm Spec), 04 Smart Roadster Coupe
    Generally if the fuel pump relay is faulty the car won't run.
     
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  16. OP
    roblloyd

    roblloyd Senior Member

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    Your Mercedes:
    R129 1990 500SL
    Just spoke to Karl from the R129 shop on ebay and he says there is not a fuel pump relay on the 89/92 500sl. BUT why the blink code? Because the car will start BUT when you put your foot down and the ASR light comes on, pedal get heavy and will not rev up.
    He told me to check the fuel pumps. Did change these with 2nd hand ones from Karl about 6 years ago.If its not them its the mas module. But surly if the mas has gone the car would not start. Lovely to drive but do your nut in when they go wrong.
    You need 2 pumps and i just looked and some are big money £70 + each, but there are pairs you can get for under £40 on ebay/amazon. Anyone had any luck with the cheaper ones?
    Rob
     
  17. LostKiwi

    LostKiwi Senior Member

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    '93 500SL-32, '01 W210 Estate E240, 02 R230 SL500 (Malcolm Spec), 04 Smart Roadster Coupe
    What exactly are the blinks you're getting? As in which pin and how many flashes?
     
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  18. OP
    roblloyd

    roblloyd Senior Member

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    Your Mercedes:
    R129 1990 500SL
    Number 14 , continuous fuel injection system (mas controller).
    14 / 2 Blinks = fuel pump relay (circuit 87) not working.
    14 /3 blinks = Tn/Td signal(rpm)interrupted.
    14 / 4 blinks =out for oxygen sensor heater control defective.
    14 / 6 blinks = output for kinkdown switch control defective.
    These are all the codes i am getting. This is because i pulled away and the ASR light came on and it sort of went into limp mode but there no limp mode in 1990 cars, so i was told.Did not come in until 1993.
    Car was running great before this happened. The car turns over but you cannot drive it, as soon as you put your foot down the ASR light comes on.
    Fuel pump relay not working must be why the other codes are coming up. Even Karl from ebay r129 shop is not 100% sure what it is. First he did say there something at the back wheels making the ASR light come on.
    Anyone any ideas?
    Rob
     
  19. davidsl500

    davidsl500 Senior Member

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    Your Mercedes:
    R172 250CDI, R129 SL500 Gone...
    Does the ASR light come on after a few minutes if you just start the car and leave it idling?
     
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  20. OP
    roblloyd

    roblloyd Senior Member

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    Your Mercedes:
    R129 1990 500SL
    Can start the car without putting my foot down. Once it as started if i put my foot down the ASR light comes on. So its ok just idling. Every time is the same.
    Rob
     

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