What is it ?

Discussion in 'Ranchero Tech Help' started by FrenchFan, Apr 18, 2019.

  1. FrenchFan

    FrenchFan In Overdrive SILVER MEMBER

    Messages:
    612
    Location:
    Rennes / FRANCE
    Does anyone know what are these black and white rectangles on the wiring diagram please ?
    Thanks.
    Eric


    [​IMG][/url]
     
  2. ForistellFord

    ForistellFord In Maximum Overdrive GOLD MEMBER

    Messages:
    14,321
    Location:
    Beautiful Foristell Missouri
    It's a teeny tiny picture, that's what.
     
  3. FrenchFan

    FrenchFan In Overdrive SILVER MEMBER

    Messages:
    612
    Location:
    Rennes / FRANCE
    It's an extract from the 1975 wiring diagram..

    [​IMG]
     
    ForistellFord likes this.
  4. ForistellFord

    ForistellFord In Maximum Overdrive GOLD MEMBER

    Messages:
    14,321
    Location:
    Beautiful Foristell Missouri
    Are they fuses?
     
  5. 72GTVA

    72GTVA Administrator Staff Member

    Messages:
    9,243
    Location:
    Chesapeake, VA
    Those depict the fuses and general the fuse block driver's side just about the floorboard outboard of the pedals..

    Funny how the link you provided is the diagrams copied from this site. I know - I have the originals and scanned them to post here.
     
  6. FrenchFan

    FrenchFan In Overdrive SILVER MEMBER

    Messages:
    612
    Location:
    Rennes / FRANCE
    Thanks 72GTVA.

    Yessss :) The link i provided was downloaded from your post , do you know if these diagrams are accurate, i asked what these rectangles were supposed to be because on the diagram the bulb of the OIL light in the instruments cluster (pin 14 of the instruments cluster connector) is protected by a fuse and in reality it seems not .....
     
  7. 72GTVA

    72GTVA Administrator Staff Member

    Messages:
    9,243
    Location:
    Chesapeake, VA
    I've never found an error in the diagrams - I will note however, that the diagrams reflect the base wiring (the wiring that exists in all models) and does not reflect option wiring such as power windows and cruise control. The options are detailed in the shop manuals or in a supplement depending on the option.

    The wiring from the engine compartment via the engine harness which contains the oil and temperature sender leads, and the lighting harness, all merge at a pair of connectors on the driver side firewall and those connectors ALL go to the fuse block although they MAY NOT be a fused circuit. The wires when not fused originate in the fuse block and form up in the wire bundle containing all the other wires.

    An easy way to reduce the amount of searching for a break in a wire is to disconnect the engine harness from the fuse block on the engine side of the firewall, locate the wire by color code and check the continuity from the pin to the sender connector. If the circuit tests good then you can narrow your search to the main wiring harness that runs from the fuse block up to the printed circuit connector. I would suspect that if there is a break in a wire it is in the engine wiring harness. In my experience, I've found broken wires in the engine harness more often than in the main dash harness.
     
  8. handy_andy_cv64

    handy_andy_cv64 In Maximum Overdrive SILVER MEMBER

    Messages:
    8,455
    Location:
    Everett, WA
    In his case, though, there's no power at the bulb (bulb is always hot, engine sender completes the ground side when oil drops below minimum PSI), so he needs to know exactly where the power wire at the cluster connector is drawing power. That's underdash, unless it leads from the connector across to the engine compartment backside to the starter solenoid.
     
  9. handy_andy_cv64

    handy_andy_cv64 In Maximum Overdrive SILVER MEMBER

    Messages:
    8,455
    Location:
    Everett, WA
    So the ground side is the white/red wire; he needs to look at the cluster part, trace the other wire, find its color code and where it terminates
     
  10. 72GTVA

    72GTVA Administrator Staff Member

    Messages:
    9,243
    Location:
    Chesapeake, VA
    On the gauge cluster, power for the oil and temp gauges is from the IVR. Not sure as I haven't traced the standard cluster what the power source is for the idiot lights.

    I'd be most concerned at this point of the answer to the question "Is there continuity at printed circuit connector from the white/red stripe wire all the way out to the connector/plug at the oil pressure switch?" A volt/ohm meter with a jumper to test that should be very simple and eliminates one leg of the problem.

    A stupid question or two: Have you replaced the oil pressure switch or tested it? Do you have the correct device (switch versus sensor)?
     
  11. FrenchFan

    FrenchFan In Overdrive SILVER MEMBER

    Messages:
    612
    Location:
    Rennes / FRANCE
    Are they these connectors you are talking about ?

    [​IMG]

    If so, is the way to remove them unscrewing the 2 bolts ?

    Thanks for your help
     
  12. FrenchFan

    FrenchFan In Overdrive SILVER MEMBER

    Messages:
    612
    Location:
    Rennes / FRANCE
    Handy_andy, the wire that feeds the OIL bulb is red and yellow, connected on the pin 14 at the cluster connector.
     
  13. FrenchFan

    FrenchFan In Overdrive SILVER MEMBER

    Messages:
    612
    Location:
    Rennes / FRANCE
    True and i think it goes behind the fuse box.... the white/red wire is connected to the pin 10 on the connector at the cluster.
     
  14. FrenchFan

    FrenchFan In Overdrive SILVER MEMBER

    Messages:
    612
    Location:
    Rennes / FRANCE
    From the wiring diagram and for the standart cluster the power source for the OIL light is the red/yellow wire connected at the pin 14 of the connector, following the printed circuit this power source is common to the OIL and BRAKE light.

    I didn't tested the continuity from the printed circuit connector to the oil pressure switch, going to do it.
    Didn't tested nor replaced the oil switch.

    I have this device on the block.
    [​IMG]
     
  15. 72GTVA

    72GTVA Administrator Staff Member

    Messages:
    9,243
    Location:
    Chesapeake, VA
    Yes, those are the connectors from the harnesses in the engine bay to the fuse block. The connector that is next to the fender is the engine/power harness. The one furtherest from the fender is the headlight harness. A 3/8" socket is the correct size for the bolt, loosen and then wiggle/gently rock the connector to disconnect. The bolt will not (should not) come out of the connector, it has a clip that keeps it in the connector.

    If you run a jumper from the white/red stripe wire at the oil pressure switch connector to your ohm meter or you have long leads on your ohm meter you don't need to remove the connector to test continuity to the printed circuit connector. I would test the entire length as it is currently installed and then if there is an open I'd then move on to test it segment by segment.
     
  16. 72GTVA

    72GTVA Administrator Staff Member

    Messages:
    9,243
    Location:
    Chesapeake, VA
    That is the correct oil pressure switch for the warning light.
     
  17. FrenchFan

    FrenchFan In Overdrive SILVER MEMBER

    Messages:
    612
    Location:
    Rennes / FRANCE
    But when i turn the ignition key to the first position (the position in which the OIL and ALT lights in the instruments cluster are checked, engine not running) the 12v doesn't follow the same wires as if these lights are lighting up for a too low oil pressure or a bad charging system, no ?
     
  18. 72GTVA

    72GTVA Administrator Staff Member

    Messages:
    9,243
    Location:
    Chesapeake, VA
    That is what is supposed to happen, yes. That the alternator light is on but the oil light is not (key on, engine off) suggests a disruption in the indicator circuit. The possible causes are:

    1- Bad connection through the light socket
    2- Bad connection at the printed circuit connector
    3- Broken wire out to the oil pressure switch
    4- Bad oil pressure switch (failed in the closed position)
     
  19. FrenchFan

    FrenchFan In Overdrive SILVER MEMBER

    Messages:
    612
    Location:
    Rennes / FRANCE
    1- I put the OIL socket and bulb at the ALT position and it worked.
    2- The printed circuit is new, checked for voltage directly on the red/yellow wire between the red/yellow wire and the ground= KO
    3-
    4- I think i have one new at home, i have to verify but will be at my daughter's for Easter.

    Thanks a lot 72GTVA, i will tell here as soon as i will progress.
     
  20. burninbush

    burninbush In Maximum Overdrive

    Messages:
    8,272
    Location:
    near SF

    They are outlines of the two connector panels on the firewall -- where they pass through into the engine compartment.
     

Share This Page