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Workshop manual for electrical testing?

Discussion in '360/430' started by brookliner7, Oct 26, 2020.

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  1. brookliner7

    brookliner7 Formula Junior
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    #1 brookliner7, Oct 26, 2020
    Greetings,
    Any recommendations on which workshop manual to purchase for a 360 that includes electrical testing?

    I am trying to testing my fuel sending unit and my pdf workshop manual( though over 1,000 pages) has no info in how to test it, just remove and replace.

    Thanks in advance!

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  2. Qavion

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    #2 Qavion, Oct 27, 2020
    Last edited: Oct 27, 2020
    Do you have a specific problem with the fuel level indications, Hans?

    Presumably the fuel sender generates a resistance which is converted to a level by the instrument panel. I guess you would want someone to provide you with specific resistance values at certain fuel levels?

    The wiring diagrams in the Workshop Manual show the path of the signal from the left hand fuel pump/fuel level sender assembly (6 contact connector) to a 12 pin plug at the back of instrument panel. All you can really do is measure the resistance of the sender and the continuity of the wiring.

    Are you familiar with the wiring diagram terminology?

    There should be a violet/yellow wire going from the left fuel pump connector "27L" to connector "22H/10H" (behind the driver's seat). From here, the violet/yellow wire goes to connector "26D/9D" (forward centre console) and then to connector 6E (behind the instrument panel). 6E is the connector on the far right of the instrument panel. Note that Ferrari identify inline connectors with two codes (rather than one)

    You could try putting a 100 ohm resistor on the violet/yellow wire (at any point in the wiring) to see if it generates a specific fuel level. The other leg of the resistor should go to earth. The wiring diagrams show a special earth for the instruments, but I assume it is attached to the vehicle chassis at some point.

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  3. brookliner7

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    #3 brookliner7, Oct 28, 2020
    This is SUPER helpful!
    Thank you!

    My driver side fuel pump and sending unit was replaced a year-and-a-half ago but now the fuel instrument guage is reading absolutely zero all time.
    Just started one day before I had a dead battery. I tried to start the car and it almost started before discharging the battery completely started clicking the starter, then my mileage when like 300,000.

    Wanted to measure the ohms from the sending unit over the next week as my fuel level drops to see if it's changing.

    Which workshop manual do you have? I have the 1,279 page PDF and somehow I don't see table L anywhere for the electrical section.

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  4. Qavion

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    #4 Qavion, Oct 28, 2020
    Last edited: Oct 28, 2020
    I recall I just bought it on eBay (Googled for the cheapest price). It's broken into two parts (473Mb and 635Mb). Obviously too big to email to you and I have an old computer which is incompatible with services like "Dropbox". The electrical section goes from A to T with additional chapters after that.

    I might be able to screenshot section L and send it to you, but my initial attempts turned out quite blurry. Can you PM me?

    Sounds like a good step to check resistances, then you can move on to the quirks of the instrument panel (I have no idea how the instrument panel processes the data).

    Is the left pump plug easy to get to or would it be better to check the resistance on plug 22H behind the driver's seat?

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    I'm not sure if the plug graphic shows the wire side of the plug or the pin side, but you can go by wire colour (violet/yellow).
     
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  5. Qavion

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    #5 Qavion, Oct 28, 2020
    I don't know if the 36o is similar to the F355, but I was told the resistance values for the F355 are as follows:

    Empty is 330 ohms, Full is 0 ohms and the warning light comes at around 270 ohms.
     
  6. brookliner7

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    #6 brookliner7, Oct 28, 2020

    Well this is a lifesaver thank you. I think I’ll go to 22H behind the seat and check The resistance coming from the fuel sending unit with an ohmmeter.

    so funny thing happened, After letting it sit for a few days, I started the car today and it read completely full, But over the course of a minute it started slowly going down to almost empty but not quite, had a few bars left.

    I turned off the car, turned it back on and it read completely zero empty.

    I turned off the car and Unplugged the harness at the fuel pump, plugged it back in, and started the car again it read full and slowly started decreasing to about the correct half full level that’s in the actual fuel tanks.

    Due to the position of the orientation of the fuel sending unit, it’s hard to get the ohm meter in there. I’ll try for 22H. Thanks again really appreciate it.

    Also ordering 100 ohm resistor.
     
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  7. Qavion

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    #7 Qavion, Oct 28, 2020
    Hopefully that 100 ohm resistor on the 10H pin/socket should give you a constant reading (somewhere between the empty warning and full). Then you can see if the gauge still behaves erratically. I just hope the sender is resistance based rather than some kind of capacitive circuit.
     
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  8. brookliner7

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    #8 brookliner7, Nov 2, 2020
    Last edited: Nov 2, 2020
    Well I’m waiting for a resistor to show up in the mail, is there anyway to test the fuel sending resistance?

    like, Can I jump on the fuel sending unit side of 27L can I Measure with the ohm meter on the fuel sending unit side of 27L on NZ and ZG?

    and on my 22H, my ZG That should be going to 27L is solid purple. shrugs.
     

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  9. Qavion

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    #9 Qavion, Nov 2, 2020
    Just measure the resistance of ZG (or in your case, Z) on 22H to any good earth. This should give you sender resistance (plus, in theory, only a few hundred milliohms for chassis resistance and wiring). This is assuming your earths are good. Since the sender resistance range is likely to be a few hundred ohms, a few hundred milliohms is not going to affect the resistance that much.

    Disconnect 22H/10H when taking measurements (to prevent errors generated by instrument circuitry)
     
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  10. Qavion

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    #10 Qavion, Nov 2, 2020
    Are 3H and 4H accessible on the car? (in post #4)
     

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