No spark, hot light?

Electrical & Ignition

  1. carguy300

    carguy300 Member

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    I need some help, my 300 just shut off yesterday. Restarted for about 15 secs and died again. Seemed to want to start after i released the key, but off again. Checked for spark out of coil, weak, yellow or none. Took out the ign switch and found someone has soldered a bridge between ign1 and ign2 terms on the switch. I replaced the switch, still wont start but now the Hot light comes on stays on all the time. key not even in. I dont know why this was done. The plug end still looks all ok. ANY ideas?
     
  2. Davea Lux

    Davea Lux Old Man with a Hat FCBO Gold Member

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    The hot light on a C-Body is normally activated by the sensor on the water pump housing being tripped and going to ground. The hot side of the circuit is fed by the ignition switch. You have 2 problems, the circuit should not be hot with the key off or there could be a short someplace between the sensor and the ignition switch. The hot light is also tested when the key is in the start position, if this is a column mounted switch, you may have it improperly adjusted so that the test circuit is not disengaging, start there.

    The no start problem could be several things. Run a voltage check to the hot side of the coil with the key on, if there is no voltage or less that 6.5 volts, there may be a problem with the ballast resistor. Next, disconnect one of the small wires from the starter relay, that will disable it. Have a helper hold the key to the start position and check the voltage to the hot side of the coil, you should have about 12.5 volts. If you have no voltage, the circuit is open and the cause must be determined. If these tests were normal, check the point resistance and the point gap. Do these things and report back. I am assuming that you did not have a hot light on before the car quit and you installed a new ignition switch. The switch can be slid up and down on the column to adjust it, the mount holes are slotted. Need to know what year car this is.
    Dave
     
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  3. carguy300

    carguy300 Member

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    My switch is in the dash. Its a 1968. Also it has been converted to electronic ignition prior to my purchase almost 2 yrs ago. This car started on the first crank everytime until 2 days ago. I am still dont know why someone would connect the 2 ign terminals on my old switch, what purpose that would. Wiring has never been my strong skill.
     
  4. carguy300

    carguy300 Member

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    This is what the back of my old switch looks like. 004.JPG
     
  5. Davea Lux

    Davea Lux Old Man with a Hat FCBO Gold Member

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    They probably did that to get 12.5 volts to the ignition at all times as this modification would negate the effect of a ballast resistor. Why they did not just take it out is beyond me. Some electronic ignition units need 12.5 volts to operate in both start and run, some do not. You should see what voltage your unit needs. If it was designed to only need 12.5 volts on the start cycle, it may be that your electronic unit has fried itself.

    Dave
     
  6. detmatt

    detmatt Old Man with a Hat FCBO Gold Member

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    How on the heck was that done without melting the back of the switch?
     
  7. carguy300

    carguy300 Member

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    That i can understand but why now my hot light comes on as soon as i hook up the battery. I hate riggin crap!
     
  8. Davea Lux

    Davea Lux Old Man with a Hat FCBO Gold Member

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    Given the high quality of the ignition switch modification, there are probably other wiring mods causing a short. Try unplugging the lead from the sensor to see if that helps, otherwise you will probably need to start by getting a wiring diagram and tracing the affected circuit wire by wire to find the problem. PIA.

    Dave
     
  9. carguy300

    carguy300 Member

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    I'll give that a try. I've a shop manual, thats my next try. I would like to get it back the way it should be. I dont believe in cutting corners when it comes to wiring. Thanks Dave for your help and time.
     
  10. Davea Lux

    Davea Lux Old Man with a Hat FCBO Gold Member

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    Just for the heck of it, you might try taking a file to remove the mod on your old ignition switch. Then reinstall it to see if the hot light stays on. If you got a repop switch made of the finest Chinesium, they are famous for poor quality.

    Dave
     
  11. carguy300

    carguy300 Member

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    I thought about that. I also thought about wrapping a wire jumper around the terms on the new one and see what happens. I bought the switch at NAPA, still made in taiwan! Dont know if they even have made in USA parts.
     
  12. Davea Lux

    Davea Lux Old Man with a Hat FCBO Gold Member

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    Another possibility for the no start situation might be your coil. This system appears to have been running 12 volts to the coil continuously. Your car has a stock coil that was designed to run on about 6.5 volts. Chrysler used 12v for a stronger spark at start but if the coil is run all the time at 12v, it will overheat and short out. You can test the coil by removing the wire from the distributor to the negative side of the coil, then turn the key to the on position and ground out the negative terminal, the coil wire to the center terminal of the distributor should have been placed about 3/8" from a good ground. When the ground is removed from the negative side of the coil it should throw a spark about 3/8" of an inch. If that happens you coil is probably still good. If you do not get a spark, be sure to check that you have voltage to the coil before buying a new one. If you have a voltmeter, you can test the pickup module in the distributor to see if it is functioning. You have the wire to the negative side of the coil already loose, hook that lead to one of the probes on the voltmeter, hook the other voltmeter probe to a good ground. Set the voltmeter to resistance. As the engine is turned over the resistance should go from infinity to a very low number, it will keep cycling as the engine is turned over. If that happens, the pickup module is still working. The pickup module fires the coil by completing the ground circuit and then removing it, that is the function of the various points on the reluctor inside the distributor.

    Dave
     
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  13. carguy300

    carguy300 Member

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    Going to be spending tomorrow to try and get it right. Thanks again for all the help. This car started on the first crank and ran like a Mopar should every time for almost 2 years and now this. I will let you know how it goes.
     
  14. HWYCRZR

    HWYCRZR Senior Member FCBO Gold Member

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    The easiest way to understand your wiring diagram is to take a photo copy of it and trace the switch circuit in color. Somewhere in this site I wrote up which actual wires do what in the ‘68 starting circuit. I will try to find it. It will help you understand while learning the circuit.
     
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  15. HWYCRZR

    HWYCRZR Senior Member FCBO Gold Member

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    68 Fury Starting issue- help!

    Here is some information. It originally was for a no crank issue. But talks about the wires going to the switch.
     
  16. HWYCRZR

    HWYCRZR Senior Member FCBO Gold Member

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    Working through your switch issues first to get rid of the hot light. I will use your switch picture and help work backwards. The schematics list the wire color, gauge and circuit number. It will help for you to look at the schematic when reading this. This is from a ‘68 Polara manual, but basic circuit should be really close.
    21B90CF5-2BDD-4EB4-A5CE-637B97F9DC36.png

    Clockwise -
    Top horizontal - ACC (Accessories), 12 gauge Black - should only feed accessories when key is on. This wire goes to a junction feeding power to the accessory side of the fuse box (12g Black), turn signal flasher (18g black), and windsheild wiper switch (16g pink) Does your heater blower, wiper or flashers work with the key off?

    Clock wise vertical ST start - 18g Yellow - Feeds T at the bulkhead junction box turning to grey on engine bay side. and goes to starting relay (shouldn't be causing issues) should only be live while cranking.

    3 O 'clock Horizontal IGN2 - 14 g Brown - feeds Q terminal at the bulkhead. In engine compartment it goes to ballast resistor on a typical points system and connects with 14 g Blue feeding + side of coil. ( This circuit is active while cranking bypassing the ballast resistor to direct feed 12 V to the coil)

    Bottom vertical Ign -16 g Dark Blue with tracer goes to bulkhead terminal N. In the engine bay it goes to your Regulator ( mounted on fire wall) that terminal connecting on the ignition side of the regulator also feeds the other side of your ballast resistor on a points ignition to drop the coil voltage while running.
    By them soldering the ign1 and Ign 2 together they are effectively bypassing the ballast resistor. There are easier ways to do this. Shouldn't be a reason for hot light.
    Vertical batt terminal - 12 g red - This is direct battery power. It is fed from the Battery to a junction on the starter relay then through the fuseable link to terminal J on the junction box. Continues through the bulk head up through the ammeter on the back side of dash panel then junctions off to the Battery side of the key switch, fuse block (battery side), headlight switch, and back out through terminal P on bulkhead to feed the battery side of Alternator.

    I am not seeing any correlation to the temperature switch (unless I am miss understanding what you mean by hot light)

    If you put the old switch back in does the light go away? I am thinking the new switch has a short between the battery and accessory or there are a couple of frayed wires that are contacting each other by the ignition switch.

    Hope this gives you a start on your switch issue. Will not fix your running issue though. Get the switch working right first. Then on to the ignition.
     
    Last edited: Nov 29, 2019
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  17. Davea Lux

    Davea Lux Old Man with a Hat FCBO Gold Member

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    This is probably going to be a fun one, because any idiot that would do that to the ignition switch probably did a bunch of other "creative" wiring mods. I suspect that this was done as part of the upgrade to electronic ignition. One would be left to wonder if the car still has the mechanical regulator installed as well.

    Dave
     
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  18. HWYCRZR

    HWYCRZR Senior Member FCBO Gold Member

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    Updated my last post above. After talking through the circuit I realized they did this to the ignition switch to bypass the ballast resistor. A simple jumper wire would have worked. It probably doesn't matter if they jumped it there or out on the fire wall. Would make it look original if the jumping was done int he switch harness and not making a mess of wires around the Ballast resistor. I don't know that soldering a bridge on switch is a good deal and could be causing some of the ignition issue. If their is a crack in the solder, the engine may start while cranking, but the minute he goes to run the power is now running through the ballast resistor (if it is still there) if it is in working order it will drop down his power and cause weak spark. Also the ballast resistor may be hooked up, but toast being the reason someone may have converted it.
    There is some hope that all the wiring isn't screwed up as someone knew what bridging that circuit would do.

    However with a new switch @carguy300 will have to make sure his ballast resistor is bypassed to get the right voltage for his electronic ignition.

    I would check the new switch first to see if it is good or not.
    Un-plugged key off position, clamp one side of the Ohmmeter to the Batt terminal none of the other terminals should have continuity.
    Key on - should have continuity from BATT to the ACC terminal and IGN 1. In crank position should have continuity from Batt to IGN 2
     
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  19. carguy300

    carguy300 Member

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    Just a quick update, I put my old switch back on and no longer had the Hot light come on when I hooked battery up, like with new one. Didnt start until I changed out the ballast. If the switch was modified to bypass the ballast, why would it burn out??? I am going to get another switch and see if Hot light stays off. At least shes running again...for now! I appreciate ALL the help.
     
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