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Troubleshooting ignition - 1950 2R512 (floor switch?)

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  • Ignition: Troubleshooting ignition - 1950 2R512 (floor switch?)

    Could use a bit of an assist on troubleshooting. Found the 6v battery was bad upon trying to start around a month ago - pulled, tested, and then replaced the battery with new. The truck sat for about a month, and now, with fully-charged battery, I get nothing when keyed-ignition on, and then pushing floor switch (no starter at all - zero) battery is delivering charge to heater blower, lights, etc.

    In the past, I found the keyed ignition a bit finicky - at times I would rock the key Lft-Rt while pushing floor switch and get intermittent ignition (but with constant starter). I don't suspect the key-ignition-switch issue has gotten any worse - I'm not even getting starter action. I've cleaned ground connections and re-tightened. I have a new switch ready to order at SI - any one have an opinion as to the likelihood that its a floor switch failure? I'm going to rig up a circuit to try to test the switch this afternoon.

    In the meantime, is it acceptable/advisable to simply jump together the two HT leads (the two that are joined by the floor switch when activated) to see if I've got a working starter and circuit (absent the switch)?
    Last edited by cavanbound; 06-26-2021, 09:21 AM.

  • #2
    You could use jumper cables direct to foot switch or starter (be sure trans is in neutral) and see what happens. Better to use a voltmeter and test voltage in and out of foot switch and at starter, ignition switch, ammeter until you find an open circuit or big voltage drop.
    "Burning Bridges...Lost Forevermore"......

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    • #3
      Be aware that the Ignition Switch has NOTHING to do with whether or not the Starter turns. So a Switch will not fix the No Start condition.

      The problem will likely be at the Solenoid, Starter Switch or Cables/Wires and their connections.
      The LAST resort is blaming the Starter, which of course COULD be the problem.
      StudeRich
      Second Generation Stude Driver,
      Proud '54 Starliner Owner

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      • #4
        StudeRich and Dwain G, thank you. I understood that the ignition was out of the circuit (for the starter), so I'm focused on floor switch. I'll rig a circuit and post back what I find. I hate auto electrics, so I think I'm stalling.

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        • #5
          Agree with Dwain, but be aware that it will make a big spark (no solenoid!). Or just use a jumper cable directly from the hot side of the battery to the big post on the starter. That will tell you whether it's the starter. Make sure you don't have wimpy 12v jumper cables.
          Skip Lackie

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          • #6
            I finally got time to install the new floor switch - and absolutely nothing at the starter. I'm going to recruit help tomorrow, pressing floor switch and checking voltage at the starter. I'll also try to connect the hot side of battery directly to starter and see what I've got. I do have good voltage from the battery, though I don't know that I have any way to test "cranking amps" - but it's not that I'm getting weak crank - I'm getting silence. If there are any other ideas, I'll report back after checking at the starter with the switch pressed, and crossing the hot-battery directly.

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            • #7
              Sorry to be an electrical novice on this one....my truck is positive-ground, so neutral is hot (right)? I connected neutral-battery-post to the line input on the starter (the same cable connection the floor switch connects to, and I got spark - but not turn. Should I get turn? I thought so, if the starter was good. I'm not certain what spark tells me, when I bypass the switch and go directly to that post....any insight is helpful here. I've actually never had a failed starter - so not sure how they behave.

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              • #8
                About now i would pull the starter and repair it. not familiar with trucks but am real cozy with grunge infested starters. a good cleaning might be all it needs. Luck Doofus

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                • #9
                  You should get a spark when you touch the starter lug with the jumper from the negative battery cable. And the starter should crank or at least growl a bit. If your battery is good, no sound from the starter means the starter is the problem. (See Doofus above.) One way to do a simple check of your battery is try the horn and/or headlights. Horn blow nice and loud? Headlights nice and bright? If not, the battery is suspect. Even a 99% dead battery will read 6v on a voltmeter.
                  Skip Lackie

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                  • #10
                    Have your helper tap on the starter body with a small hammer while you activate the foot switch.
                    "Burning Bridges...Lost Forevermore"......

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                    • #11
                      I hadn't thought of tapping on it - I'm getting no sound at all, but I suppose it could be stuck/seized. I didn't have time to pull the starter today, but did test voltage - when wife-helper hits the foot switch, I get 4 volts at the hot-connection on the starter. I thought that was interesting (not 6v), but maybe that's normal for older wiring, etc. The starter was strong and without issue until this time - no weak/fade/etc. I'll try a light tap with hammer, just in case

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                      • #12
                        could be a flywheel gear- starter gear lock up. Try turning motor by hand vie fan or put in hi gear and rock truck back and forth.

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                        • #13
                          That starter is not gonna do anything with 4 volts. Either you have a bad connection or a dead battery. Did you try the headlight/horn test?
                          Skip Lackie

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                          • #14
                            Your starter or starter drive has failed. You get no sound as it has locked up. The voltage drops to 4 when you attempt to crank as it is nearly the same as a dead short when the starter can not turn. Put the truck in 3d gear and rock it if you can or grab the fan and see if you can bump the motor over a bit.

                            I had this exact problem on a 53 Packard with a very worn bendix drive. On a start attempt there was silence but the idiot lights on the dash would all but go out. Fooled me a couple of times before I figured what was actually happening. In the last instance I had let the car roll back out of its parking spot and pop the clutch to free the jammed bendix. The car started perfectly then and I drove it home and changed the very tired looking bendix.

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