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    Electrical problem on 66 instrument panel

    The gauges on my 66 had been reading only about half way, i.e. fuel only half, oil pressure low and temperarture barely moving. I bought a new voltage regulator, but no change. I have checked the senders, they seem OK and fuel sender is new. I checked voltage across regulator terminals, 12v coming in and clicking on/off on the other a little quicker than every second. Earthing of the panel casing seems fine.
    What do I check next?
    Just one thing that may be a pointer: when the instrument panel is out and is not earthed, switching on the lights illuminates the instrument panel lights but also the indicator lights. Once the panel is earthed, noral activity resumes.
    Ideas?
    1966 V8 convertible
    1969 Mach 1 428CJ
    2012 Shelby GT500
    1951 Ford Custom Deluxe

    #2
    Originally posted by jeremyfd View Post
    The gauges on my 66 had been reading only about half way, i.e. fuel only half, oil pressure low and temperarture barely moving. I bought a new voltage regulator, but no change. I have checked the senders, they seem OK and fuel sender is new. I checked voltage across regulator terminals, 12v coming in and clicking on/off on the other a little quicker than every second. Earthing of the panel casing seems fine.
    What do I check next?
    Just one thing that may be a pointer: when the instrument panel is out and is not earthed, switching on the lights illuminates the instrument panel lights but also the indicator lights. Once the panel is earthed, noral activity resumes.
    Ideas?
    If you take the wire off the temp sender and earth it Jeremy the temp gauge should go across to max as should the others if tried in turn.

    If the panel is out, unearthed, switching on the lights will illuminate the indicator lights because that's where the lights are finding an earth source whilst the panel itself isn't earthed.

    HTH :)
    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


      #3
      Originally posted by Geoff Watts View Post
      If you take the wire off the temp sender and earth it Jeremy the temp gauge should go across to max as should the others if tried in turn.

      If the panel is out, unearthed, switching on the lights will illuminate the indicator lights because that's where the lights are finding an earth source whilst the panel itself isn't earthed.

      HTH :)
      Which is OK, right? or not? and if we assume it is OK, and the senders are fine, what do I look for next? getting my head around electrics is not my forte!
      1966 V8 convertible
      1969 Mach 1 428CJ
      2012 Shelby GT500
      1951 Ford Custom Deluxe

      Comment


        #4
        If you earth each of the sender wires briefly in turn the relevant gauge should go to max. Don't leave them earthed longer than necessary to do the test or the gauge can be damaged. If they all only register half way the problem is with the supply voltage. This should oscillate on a meter between 0 and 10 volts giving an average of 5, it does this because the gauges operate with a bimetal strip inside and a constant voltage of 5 (which some other regulators give out) would eventually ruin the gauges in the long term. Some gauges on other cars are designed to work on a constant limited voltage, these are not, you have to have the correct voltage regulator but they can be tempramental things.

        The indicator lights illuminating with the dash lights while the dash earth is disconnected is as would be expected and nothing to do with your problem
        Last edited by GeoffW; 26-05-2007, 06:59 PM.
        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


          #5
          Originally posted by Geoff Watts View Post
          If you earth each of the sender wires briefly in turn the relevant gauge should go to max. Don't leave them earthed longer than necessary to do the test or the gauge can be damaged. If they all only register half way the problem is with the supply voltage. This should oscillate on a meter between 0 and 10 volts giving an average of 5, it does this because the gauges operate with a bimetal strip inside and a constant voltage of 5 (which some other regulators give out) would eventually ruin the gauges in the long term. Some gauges on other cars are designed to work on a constant limited voltage, these are not, you have to have the correct voltage regulator but they can be tempramental things.

          The indicator lights illuminating with the dash lights while the dash earth is disconnected is as would be expected and nothing to do with your problem
          Sender wires at the sender end tested and gauges go to max. Voltage regulator tested and oscillating every second or so. What next?
          1966 V8 convertible
          1969 Mach 1 428CJ
          2012 Shelby GT500
          1951 Ford Custom Deluxe

          Comment


            #6
            Originally posted by Geoff Watts View Post
            If you earth each of the sender wires briefly in turn the relevant gauge should go to max. Don't leave them earthed longer than necessary to do the test or the gauge can be damaged. If they all only register half way the problem is with the supply voltage. This should oscillate on a meter between 0 and 10 volts giving an average of 5, it does this because the gauges operate with a bimetal strip inside and a constant voltage of 5 (which some other regulators give out) would eventually ruin the gauges in the long term. Some gauges on other cars are designed to work on a constant limited voltage, these are not, you have to have the correct voltage regulator but they can be tempramental things.

            The indicator lights illuminating with the dash lights while the dash earth is disconnected is as would be expected and nothing to do with your problem
            Sorry to interject on this but having suffered similar i would like to be clear: Geoff are you referring to the voltage regulator on the radiator supporting panel in engine bay or the voltage stabiliser found at the rear side of the instrument panel?

            If the latter, are you saying that the old bimetallic version is better than the electronic version (and the Maplin's 79p stabiliser discussed on other threads)?

            many thanks and sorry to butt in!

            RDS

            Comment


              #7
              No problem with the butt in, more heads the merrier :)

              I'm referring to the voltage stabiliser/limiter call it what you like that fits at the back of the dash and feeds the instruments with regulated power ;)
              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


                #8
                Originally posted by jeremyfd View Post
                Sender wires at the sender end tested and gauges go to max. Voltage regulator tested and oscillating every second or so. What next?
                Can't see why they don't work correctly then, earthing the wire is only simulating the sender being at it's lowest resistance

                Sure it's not the tank half full, the engine doesn't get very hot and there isn't much oil pressure :D
                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


                  #9
                  Originally posted by Geoff Watts View Post
                  No problem with the butt in, more heads the merrier :)

                  I'm referring to the voltage stabiliser/limiter call it what you like that fits at the back of the dash and feeds the instruments with regulated power ;)
                  I suppose in the end I am going to have to (a) remove panel completely and check for shorts, and/or (b) maybe check wiring for dodgy bits. Electrical gremlins are the worst.
                  1966 V8 convertible
                  1969 Mach 1 428CJ
                  2012 Shelby GT500
                  1951 Ford Custom Deluxe

                  Comment


                    #10
                    Originally posted by Geoff Watts View Post
                    Can't see why they don't work correctly then, earthing the wire is only simulating the sender being at it's lowest resistance

                    Sure it's not the tank half full, the engine doesn't get very hot and there isn't much oil pressure :D
                    Good point, but no the tank is full, the temp gauge hardly moves and oil pressure is fine, should be midway or so.
                    By the way, should the amp gauge jump around a bit or just very slightly flicker?
                    Actually, what I will check is the earth strap from engine to bulkhead, I presume the 66 is supposed to have one, right? I remember this was an issue in my 68.
                    1966 V8 convertible
                    1969 Mach 1 428CJ
                    2012 Shelby GT500
                    1951 Ford Custom Deluxe

                    Comment


                      #11
                      Originally posted by jeremyfd View Post
                      Good point, but no the tank is full, the temp gauge hardly moves and oil pressure is fine, should be midway or so.
                      By the way, should the amp gauge jump around a bit or just very slightly flicker?
                      Actually, what I will check is the earth strap from engine to bulkhead, I presume the 66 is supposed to have one, right? I remember this was an issue in my 68.
                      Aaah, amp gauges are renowned for hardly moving at all, if yours is flickering it's a poor connection on the positive side to the panel that will be causing the other gauge issue too. It's not an earthing issue with the gauges because the earth for each gauge is fed in a variable manner by the respective senders as you've tested out;)
                      Last edited by GeoffW; 26-05-2007, 10:17 PM. Reason: typo
                      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


                        #12
                        Originally posted by Geoff Watts View Post
                        Aaah, amp gauges are renowned for hardly moving at all, if yours is flickering it's a poor connection on the positive side to the panel that will be causing the other gauge issue too. It's not an earthing issue with the gauges because the earth for each gauge is fed in a variable manner by the respective senders as you've tested out;)
                        Yes my amp gauge hardly moves at all.
                        I will check today that the regulated voltage is getting through to the other gauges.The wire seems to take a pretty totuous route and I've not followed it all the way through the loom yet.
                        1966 V8 convertible
                        1969 Mach 1 428CJ
                        2012 Shelby GT500
                        1951 Ford Custom Deluxe

                        Comment


                          #13
                          Ah ammeter problems. I did a lot of investigating of this on my '66 last year. The ammeter is actually a votmeter and mesures the votage drop from the soleniod to further up a particular wire. However there are connectors on this wire and if there is even a small resistance caused by corrosion then the ammeter will hardly read. I spent some time cleaning these all up and my ammeter is better, not perfect.

                          I hope that helps.
                          Mark Newton
                          MOCBG # 0823
                          '66 289 auto Convertable

                          Ever stopped to think, and forget to start again?

                          Comment


                            #14
                            Gauges

                            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.

                            Comment


                              #15
                              oil presure

                              Hi Jeramy, While an electrcal problem could indeed cause false readings on the fuel gauge and volt metre I would not expect it to affect the oil preasure. Unlike modern cars which pick up from an electrical sensor in the engine block older cars like ours usually have a pipe comming fron a union in the block to the back of the gauge to measure the oil preasure direct. Now if you have low oil preasure I would get a new gauge, say off ebay, they are only about 10 to get another reading to prove weather your gauge is reading low. If the new gauge also reads low then it's looking a bit more serious. Could be a worn oil pump or main bearings or even big ends or all of them. Years ago a really good mechanic told me if the oil light comes on when your driving then its usually too late, the damage is done.

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