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Check your power distribution bus

Discussion in '365 GT4 2+2/400/412' started by It's Ross, Feb 7, 2020.

  1. It's Ross

    It's Ross Formula 3

    Jul 30, 2007
    1,983
    Barrington, Ill. USA
    Full Name:
    Ross
    #1 It's Ross, Feb 7, 2020
    Last edited: Feb 7, 2020
    So, while tracking down a non-existent electrical gremlin I spied a very distressed looking power bus, connections and wires to it. It is on the relay panel in the foot well.
    Essentially every circuit in the car is fed through there. A large wire coming off the amp meter shunt connects with a flimsy quick connect to a four terminal bar with spade connectors for the other three connections serving seven wires.

    The supply wire from the shunt had clearly been very hot, discolored and stiff is a board as the insulation had melted into the wire. Another pair on one terminal was less distressed but clearly has also been hot at some point. The plastic terminal covers were crisp and the bus' plastic covering discolored from heat too.
    I believe the cause is those quick connects becoming loose over time and increasing resistance, a poor choice of connector to begin with.

    I've replaced this set up with a marine power bus and ring terminals for each individual circuit served.
    The wiper relay is relocated to the front of the panel while I mounted the new bus in the old wiper relay's position.
    The part used was inexpensive, "Bay Marine Supply Bus Bar" I used the version with 5/16" dia. posts, $20 from Amazon and the time was nominal.
    I think I dodged a bullet here, perhaps worth a look on your car too.

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    The bus as purchased has posts which are too tall for mounting as I did. The device is easily altered, as the posts are merely hex bolts captured by the bar. Shorter bolts solved the problem.
    Hope this helps others, cheers,
    Ross
     
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  2. raemin

    raemin Formula Junior

    Jan 16, 2007
    322
    Lyon (FR)
    Full Name:
    R. Emin
    Here is how mine looked...

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    I've finally crimped and soldered all cables to individual connectors and bolted them directly on the circuit breaker (without distribution bus). Made a huge difference.

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    Also found this ugly flashing relay connection! Probably done by the local dealer in order to circumvent the italian law, but that's not exactly what the manual recommends! Sorry, for the not so explicit picture (I took the photo while chasing the gremlins a while ago). The connector is the one next to the gearbox selector, the flashing relay cable (red with black strip) can be used to enable headlight flashing (which was forbiden in italy). The manual recommend to route this cable to the toggle switch of the fog light. As the cable is too short, someone just inserted it against the back of the connector (no crimp, no soldering) and secured with a zip tie.

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  3. It's Ross

    It's Ross Formula 3

    Jul 30, 2007
    1,983
    Barrington, Ill. USA
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    Ross
    Breaker seems a good idea. What is the rating of your breaker?
     
  4. SouthJersey400i

    SouthJersey400i Formula 3

    Mar 14, 2007
    1,202
    Romulus, NY (Finger Lakes)
    Full Name:
    Ken Battle
    Ross, year and model car?
     
  5. samsaprunoff

    samsaprunoff F1 Rookie
    Silver Subscribed

    Jun 8, 2004
    2,996
    Edmonton, AB Canada
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    Sam Saprunoff
    Good day All,

    Just to have a bit of a comparison...your (400i series) foot well relay panel looks to be far more modern than the 365 version (see picture). My 365 panel looks entirely hand fabricated... from cutting of the phenolic base panel to mounting of the relays, etc. In fact the upper portion of the panel shows that it is/was specific to my car, as the build number is clearly present (pretty cool I would say).

    Cheers,

    Sam

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  6. raemin

    raemin Formula Junior

    Jan 16, 2007
    322
    Lyon (FR)
    Full Name:
    R. Emin
    Compared to yours, the only thing they added to the design on my late gen1 400i, are more modern relays and a plastic housing! Actually this is more or less the same wiring harness as yours (with numerous 6.3mm connectors), except that there is an additional base plate that holds all these connectors together. underneath the base plate, one can contemplate the spaghetti wirings just like yours. The advantage of the housing is obviously that when changing relays, there is less risk to invert connectors in the process. Does not look as nice as yours though, but these are just as easy to fix or beef-up.

    These handcrafted harness are a real plus compared to later Gen2 and 412 cars that were upgraded with the flimsy board. As a bonus in the latest variants, a few bits were removed (Kjet pulse relay) so there is room for additional relays and accessories.
     
  7. It's Ross

    It's Ross Formula 3

    Jul 30, 2007
    1,983
    Barrington, Ill. USA
    Full Name:
    Ross
    Mine is '82 400i
     
  8. It's Ross

    It's Ross Formula 3

    Jul 30, 2007
    1,983
    Barrington, Ill. USA
    Full Name:
    Ross
    They are both pretty rustic.
     
  9. Rifledriver

    Rifledriver Two Time F1 World Champ

    Apr 29, 2004
    26,871
    Austin TX
    Full Name:
    Brian Crall
    The boards you speak of were a real issue even when the cars were new. In the late 80's I was fixing so many 400 electrical issues I rarely even needed an electrical diagram I became so familiar with them. I remember quite clearly doing one and came to the realization is was recognizing color codes from memory and thinking I was spending too much time in 400 footwells.
     
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  10. raemin

    raemin Formula Junior

    Jan 16, 2007
    322
    Lyon (FR)
    Full Name:
    R. Emin
    Just to make myself clear I am talking about the late variants of generation 1 board (1982), not gen2. This is actually the most simple board made for injected cars: earlier board add the k-jet pulse relay, later board had the modern all-in one design (fuse & relays on the same board). With the twin alternators, this is probably the most reliable (as per Ferrari of that era standards...) of the lot.

    Carbs (365 or 400) have the advantage here of less power hungry pumps and no relays for the kjet so presumably even more reliable. My two brothers (365 & 400 carb) never had to remove the carpets...
     
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  11. raemin

    raemin Formula Junior

    Jan 16, 2007
    322
    Lyon (FR)
    Full Name:
    R. Emin
    That's the type approved for Rally that you usually put on the fender, presumably 100A but totally overkill. There was one in the 365, very nice with an aluminium key. It was probably from the factory as there is a dedicated recess next to the battery bay. I wanted something similar on the 400i so added it to relay panel (it does exit between the carpet and the glove box).

    Something like this one, but with a slightly lower profile.

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  12. Rifledriver

    Rifledriver Two Time F1 World Champ

    Apr 29, 2004
    26,871
    Austin TX
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    Brian Crall
    Thats not a breaker, thats a battery switch. Breakers are automatic and shut off when load goes too high.
     
  13. Al Campbell

    Al Campbell Formula Junior
    Silver Subscribed Owner

    Nov 22, 2013
    411
    Australia
    My 400i has one of these isolation switches installed just underneath the ignition switch by a previous owner.
    It's nice and handy if you need it in a hurry & is great for isolating the power when not in use.
    Mine is installed in the ground between the battery negative & the chassis.
     
  14. SouthJersey400i

    SouthJersey400i Formula 3

    Mar 14, 2007
    1,202
    Romulus, NY (Finger Lakes)
    Full Name:
    Ken Battle
    That switch means your clock will always need to be reset and your radio presets will be lost. I drive my car too much for such a hassle.
     
  15. It's Ross

    It's Ross Formula 3

    Jul 30, 2007
    1,983
    Barrington, Ill. USA
    Full Name:
    Ross
    My car already has the shut off near the battery, presumably from the factory.
    The breaker seems a good idea but I'm contemplating the rating to use. 100a as you say is total overkill so useless as the harness will be on fire well before 100 amps passes through any of this wiring.
    I have a 50a on hand and may install this. Seems a reasonable starting point.
    Thoughts from others?
     
  16. raemin

    raemin Formula Junior

    Jan 16, 2007
    322
    Lyon (FR)
    Full Name:
    R. Emin
    That's the reason why I dropped the Becker Grand Prix Electronic in favour of a period correct Philips with mechanical presets! Got to agree that there is still an issue with the clock... I just have to refrain from adjusting it in order to save the gears.

    Call me paranoid I also shoehorned a 90Ah battery and a modern starter. At least I do not have to pray when I attempt to crank the engine in the middle of nowhere.
     
  17. raemin

    raemin Formula Junior

    Jan 16, 2007
    322
    Lyon (FR)
    Full Name:
    R. Emin
    When the starter solenoid gets stuck it draws an important amount of amps that passes through the shunt (the rest of the starter has its own dedicated circuit). Locked solenoid & pumps could easily reach 40A on my car. That's the maximum I've experienced so far on my car. So 50a could do the trick.

    Please note that I am not sure on the breaker: I would avoid to add something that could play havoc with the ignition and the headlights. With a breaker you would loose the benefits of the redundant electrical setup: left and right headlights and beams are on 4 separate circuits so as to avoid total lighting loss. Imagine being in the night without hazard lighting? Driving at high speed and loosing lighting?
     

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