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Electrical problem on 66 instrument panel

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    #16
    Originally posted by Paul.Lehrer View Post
    Had the same problem with my car, fuel gauge not reading properly, temperature up, oil pressure reading low etc, had it checked out by a car electrician problem was bad light switch changed this out now is fine.
    Hadn't thought of that one. Why would it affect the instrument panel? Does the panel get its feed from the light switch?
    1966 V8 convertible
    1969 Mach 1 428CJ
    2012 Shelby GT500
    1951 Ford Custom Deluxe

    Comment


      #17
      Gauge

      Quote:
      Originally Posted by Paul.Lehrer View Post
      Had the same problem with my car, fuel gauge not reading properly, temperature up, oil pressure reading low etc, had it checked out by a car electrician problem was bad light switch changed this out now is fine.

      Hadn't thought of that one. Why would it affect the instrument panel? Does the panel get its feed from the light switch?
      __________________
      66 V8 convertible
      05 GT (spoiler delete option!)

      Honestly donít know just got it fixed and left it at that, sorry I cant be of more help,

      Paul

      Comment


        #18
        Awfully sorry but I can't see any logic behind that at all unless someone can explain differently. The lights operate completely independant of the ignition circuit, the light switch works whether the ignition is on or off. The gauges only work when the ignition is on so the source of supply is not from the light switch but from a source determined by the ignition switch.

        The feed to the loom from the voltage stabiliser is black with a green stripe in the '67 wiring diagram I've got, I would asume the 66 to be the same or similar. Trace where that goes Jeremy, probably to a multi-connector which could be "iffy";)
        1967 White Convertible Auto ...... 1994 to 2004
        2005 Redfire GT Manual......2008 to 2010
        2010 Kona Blue GT Auto ...... 2010 to 2013


        MOCGB #332 since 1994

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          #19
          May have been a coincidence I just had it fixed

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            #20
            OK so I have my 66 workshop manual out, I am re-checking the wiring diagram and also the instrument panel wiring diagram.
            It shows the feed into the constant voltage unit, the wires out are Black/green, but to my surprise there is a separate ground wire shown on the unit. I only just noticed.
            At the same time the instrument panel does not show any ground. In all diagrams where there is a ground it is shown.
            Can I take it that only the constant voltage unit should be grounded and not the instrument panel itself? at the mo the voltage unit is screwed on to the back of the panel and has what is obviously a makeshift ground wire attached to the screw which is also grounding the instrument panel case.
            This is getting interesting!
            BTW the oil pressure gauge on the 66 is electric, there's a sender called "oil pressure sending unit Mustang only".
            1966 V8 convertible
            1969 Mach 1 428CJ
            2012 Shelby GT500
            1951 Ford Custom Deluxe

            Comment


              #21
              There should be 2 wires on the voltage stabiliser, one in at 12v and one out to the instruments which is restricted voltage. The unit itself is grounded by being attached to the instrument panel which should, itself, be earthed for the instrument lighting etc.
              1967 White Convertible Auto ...... 1994 to 2004
              2005 Redfire GT Manual......2008 to 2010
              2010 Kona Blue GT Auto ...... 2010 to 2013


              MOCGB #332 since 1994

              Comment


                #22
                Hi ,
                there is some good info in Mustang monthly /tech articles about gauges.
                But Geoff is right in what he is saying.
                there are two wires going to the voltage regulator behind the panel.One is coming from the ignition and brings 12v (inlet if you like) the other one delivers roundabout 5v, to the gauges(this is when they work better)
                1-check if your gauges are receiving 5v
                2-you can ground the terminals in the sender side to see ,if the needle peg.(you have to do it really fast ,because you can burn the coil of the gauge, I saw a nasty fume the first time that I did it on the fuel gauge.
                If the sender unit is bad,the gauge will either be inoperative or it will climb to the max position and stay there.
                Most of the time the sending units are the problem.
                3-the other thing could be a rusty conection or a brocken wire.You can perform a continuity test from the wire in the gauge, to the sender, or measure resistance, in both extremes of that particullar cable.It should be 0 ohms, when the cable is ok.
                4-Now when you turn the ignition key and all the needles peg to max in all the gauges, that means that the voltage regulator is fused or inoperative,because , is not "converting 12v into 5 as it should be. ( it happend to me)
                Now, the voltage reg does have a ground wich is the panel,(the bolt that holds it to the cluster)and there is another black cable that goes to the support arm that is part of the frame if you like.
                you gota have a good ground.Check that as well.
                The other thing you can do is swap gauges to see how they behave.It is not normal ,but sometimes it could be that after a short the coil lost resistance due to the temperature created by the short.
                All the gauges are the same(fuel/temp/oil press, is just a variable resistance in the sender.
                Best of luck
                Mat

                Comment


                  #23
                  My comments in italics:
                  here is some good info in Mustang monthly /tech articles about gauges.
                  (Saw this and follwed their instructions)
                  But Geoff is right in what he is saying.
                  there are two wires going to the voltage regulator behind the panel.One is coming from the ignition and brings 12v (inlet if you like) the other one delivers roundabout 5v, to the gauges(this is when they work better)
                  (The 66 has the one 12V wire going in to the voltage regulator unit, then a single connector with two wires @ 5V going out, one goes to the fuel guage/oil pressure side, and the other loops round via the loom to the temp gauge)
                  1-check if your gauges are receiving 5v
                  (Checked, there is no steady 5V it bounces between 11V or so and 0V about once a second as the bimetallc strip heats and cools)
                  2-you can ground the terminals in the sender side to see ,if the needle peg.(you have to do it really fast ,because you can burn the coil of the gauge, I saw a nasty fume the first time that I did it on the fuel gauge.
                  (All sender units have been checked and are OK)
                  If the sender unit is bad,the gauge will either be inoperative or it will climb to the max position and stay there.
                  Most of the time the sending units are the problem.
                  3-the other thing could be a rusty conection or a brocken wire.You can perform a continuity test from the wire in the gauge, to the sender, or measure resistance, in both extremes of that particullar cable.It should be 0 ohms, when the cable is ok.
                  (Not done this yet, will do)
                  4-Now when you turn the ignition key and all the needles peg to max in all the gauges, that means that the voltage regulator is fused or inoperative,because , is not "converting 12v into 5 as it should be. ( it happend to me)
                  (Not my problem, mine is they only read half way)
                  Now, the voltage reg does have a ground wich is the panel,(the bolt that holds it to the cluster)and there is another black cable that goes to the support arm that is part of the frame if you like.
                  (Check - the black wire is there and it goes to frame for earthing)
                  you gota have a good ground.Check that as well.
                  The other thing you can do is swap gauges to see how they behave.It is not normal ,but sometimes it could be that after a short the coil lost resistance due to the temperature created by the short.
                  All the gauges are the same(fuel/temp/oil press, is just a variable resistance in the sender.
                  (Good idea I'll try this out)
                  Best of luck
                  Mat[/QUOTE]
                  1966 V8 convertible
                  1969 Mach 1 428CJ
                  2012 Shelby GT500
                  1951 Ford Custom Deluxe

                  Comment


                    #24
                    Hey one thing ...
                    do they read half way as soon as you turn the ignition key?
                    In may car for example,when I was having this "electrical nightmare"the problem was as soon as I turn the key.All needles Peg.
                    Right now when I turn the key, the only one that moves is the fuel gauge, because is indicating the amount of fuel(obviously),but the oil will start to move when the engine start to cranck, and the temp as well as she warms up.
                    Good luck
                    Mat

                    Comment


                      #25
                      Just picked up on this thread - have a similar problem with my '67 and I'm fairly convinced the average voltage is a bit low to the instruments.

                      Was intending to build the Maplin 5v stabiliser but after reading this I'm not so sure

                      Geoff - could you clarify - fitting a constant 5v stabiliser like the Maplin one will damage the instruments?

                      If so will have to order the (expensive by comparison) original type from NPD

                      Thanks
                      Gary
                      Last edited by Norfolk Mustang; 30-05-2007, 12:01 PM.

                      Comment


                        #26
                        Originally posted by Norfolk Mustang View Post
                        Geoff - could you clarify - fitting a constant 5v stabiliser like the Maplin one will damage the instruments?

                        If so will have to order the (expensive by comparison) original type from NPD

                        Thanks
                        Gary

                        The content of post #4 about the right stabiliser was quoted from my 60's Ford manual so I thought it relevant.
                        1967 White Convertible Auto ...... 1994 to 2004
                        2005 Redfire GT Manual......2008 to 2010
                        2010 Kona Blue GT Auto ...... 2010 to 2013


                        MOCGB #332 since 1994

                        Comment


                          #27
                          Originally posted by Geoff Watts View Post
                          The content of post #4 about the right stabiliser was quoted from my 60's Ford manual so I thought it relevant.
                          Other thread contributors have suggested the Maplin fix and i've gone that way too, however donit know if i have damaged things yet as have other issues i need to sort first, however Geoff I presume the 60s Ford manual was printed before the widespread use of transistors etc like the solid state voltage stabiliser? so that there might not be such an issue.

                          Interestingly NPD sell a transistorised stabiliser as well as a bi-mettalic type.

                          Comment


                            #28
                            Originally posted by jeremyfd View Post
                            4-Now when you turn the ignition key and all the needles peg to max in all the gauges, that means that the voltage regulator is fused or inoperative,because , is not "converting 12v into 5 as it should be. ( it happend to me)
                            Re-reading that Mustang Monthly Article i see that it is possible to re-calibrate the gauges by re-setting them simply by turning a screw internally, however this is mentioned only in passing.

                            When at rest, are your needles very very far to the left?

                            Anyone know where the needles are supposed to return to at rest, eg before the start of the white lines or dead on?

                            Comment


                              #29
                              What is causing severe head scratching with Jeremys dilemma is the fact that if the sender wires are earthed the gauges read max so everything would appear to be as it should. There's no point in recalibrating the gauges because they are working right when tested.

                              The only clue is the fact that the ammeter, normally dormant more or less, is flickering pointing to a poor connection to the instruments as a whole.

                              Presumably they were all working fine recently and now they're not, it's got to be something "simple" causing everything :)
                              1967 White Convertible Auto ...... 1994 to 2004
                              2005 Redfire GT Manual......2008 to 2010
                              2010 Kona Blue GT Auto ...... 2010 to 2013


                              MOCGB #332 since 1994

                              Comment


                                #30
                                Originally posted by Geoff Watts View Post
                                What is causing severe head scratching with Jeremys dilemma is the fact that if the sender wires are earthed the gauges read max so everything would appear to be as it should. There's no point in recalibrating the gauges because they are working right when tested.

                                The only clue is the fact that the ammeter, normally dormant more or less, is flickering pointing to a poor connection to the instruments as a whole.

                                Presumably they were all working fine recently and now they're not, it's got to be something "simple" causing everything :)

                                I see yes - in my case the simple cause was the teminals of the fuel gauge moving slightly on reassembling the instrument panel and shorting on the case. Its only ever "simple" afer the issue is solved!

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