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Posted By Discussion Topic: electrical troubleshooting -- page: 1 2     fordmerc 04-28-2010 @ 5:42 PM reply profile send p.m. New Member Posts: 180 Joined: Oct 2009 '39 problem: With ignition switch ON, wire from ignition switch through resistor shows lots of current (blew my multimeter fuse) (engine not running).With wire to coil disconnected, that terminal on coil is grounded. Is this right? The odyssey started because with ignition switch ON, smoke and smell come from under the dash. I did not do well in physics class so I need help and comments. jerry.grayson 04-28-2010 @ 6:28 PM reply profile send p.m. New Member Posts: 128 Joined: Oct 2009 I don't understand your comment about the wire from the coil disconnected, that terminal grounded?? Anyway, it sounds like you have a dead short somewhere. deluxe40 04-28-2010 @ 6:30 PM reply profile send p.m. Member Posts: 413 Joined: Oct 2009 Sounds like a short between the ignition switch and the coil. Given that the smoke and smell come from under the dash, I'd guess it is the wire between the switch and the resistor or the resistor itself. I would disconnect the battery and pursue the problem with an ohm meter. Check to see if the terminal on the switch that goes to the resistor is grounded. If so, disconnect the wire at the resistor and see if it is still grounded, etc. The problem has to be in the ignition switch, the wire to the resistor, the resistor, the wire to the coil, or the coil itself. Eliminate one at a time until you find it. On a second reading of your question I am thinking that the terminal on the coil is what you found grounded. That could be normal if the points are closed. The circuit goes through the primary windings on the coil and through the points to ground. I'd still proceed as described above (with the wire to the coil and the battery disconnected). This message was edited by deluxe40 on 4-28-10 @ 6:34 PM TomO 04-29-2010 @ 7:20 AM reply profile send p.m. Senior Posts: 7258 Joined: Oct 2009 If your points are closed or shorted you will have lots of current flowing through the ignition resistor. A shorted condenser will also cause this problem. Use your voltmeter to check the voltage at the input to the coil. Tap the starter to see if the voltage changes from about 3.5V to about 6V. If it does everything is normal. If it doesn't, check the condenser and the points. Tom supereal 04-29-2010 @ 11:48 AM reply profile send p.m. Senior Posts: 6819 Joined: Oct 2009 Do you have a wiring diagram for your car? It is a required "road map" to tracing your wiring. I agree with the others it is likely you have a short in the circuit between the output of the resistor and the coil. As the smoke and smell came from under the dash, look for obvious signs of burned wires or connections. The coil is grounded thru the points when they are closed. When they are open, you will read battery voltage at the coil. It is nearly impossible to troubleshoot using the ammeter part of a multimeter because most can handle only ten amps or less. The fuse saved your meter. Use the ohmmeter portion to check for shorts. Put the meter on the 1X scale and test the wires both for continuity and for a ground to the body of the car. If you need a diagram, I can post one. fordmerc 04-29-2010 @ 6:40 PM reply profile send p.m. New Member Posts: 180 Joined: Oct 2009 I have the wiring diagrams, have annotated them in color and will proceed with multimeter in hand to go step by step. Thanks 37RAGTOPMAN 04-30-2010 @ 5:19 AM reply profile send p.m. Senior Posts: 1966 Joined: Oct 2009 hi fordmerc first thing is disconnect the primary wire going to the coil,on the coil-distributer itself, this will rule out if coil-distrubuter is your problem, turn the ignition switch on, and check for voltage on the end of that wire,, should be around 3 1/2 volts, make sure you turn on and off a few time to see if the ignition switch is ok, also.you shoulod see the needle on the meter go back and forth, if you take the wires off the back of the ignition switch, there are 2 screws that hole it together,if you remove them the switch will come apart, you can examine for any problems, also you can clean the brush , and with a piece of flat glass and a piece of 320 fine sandpaper take the bakelite piece that has the brass contacts and hold flat on the glass with and draw the switch back and forth till it is flat, the brush wears gooves in the switch,[ over years,] and brass contacts,this will flaten out the baklite piece, if it is to worn find a replacement, you can also add tension to the brush brass pieces by carefully bending them to add a little tension, if the dist is your problem, it can be a few different possibles, one problem, is we had a guy got stuck because the of the leather diaphram [ the vacuumn advance in the distributer grounded,just rotted away, does the car run,? you never told us, the more info, the EASIER it is to figure out, is the wiring new ? is it old and frayed, maybe gounding out along the way, is the primiary wire going though the metal conduit, you should examine the wires carefully, and trace the wires, also is there any other wire connected to the ignition side of the ignition switch,? if so disconnect that and check the circuit again, and then recheck, the resister does get hot,especially with the car not running and ign on, points will burn out,will build up a carbon on them , and causing them not to arc,so no starting, hope this helps, looking for a comeback on your problem KEEP ON TRUCKIN,,,,,,!!! 37RAGTOPMAN fordmerc 04-30-2010 @ 6:31 AM reply profile send p.m. New Member Posts: 180 Joined: Oct 2009 I'm headed to the old garage; In answer to the question the car starts and runs, all new wiring, rebuilt coil, rebuilt generator, rebuilt distributor, new battery. Everything has been torn apart and reassembled. All gauges and switches worked on the bench. I will retrace wire connections and circuits again. I am also going to check each connector post for a short. Obviously, I didn't do well in physics class and found electricity shockingly complex. Thanks to all for help. supereal 04-30-2010 @ 11:28 AM reply profile send p.m. Senior Posts: 6819 Joined: Oct 2009 The last time I saw smoke from under the dash of one of my cars, it was caused by a short at the ignition switch. A terminal on the wire to the ignition had come in contact with metal case of the switch. fordmerc 04-30-2010 @ 2:57 PM reply profile send p.m. New Member Posts: 180 Joined: Oct 2009 additional follow-up: New resistor on resistor-fuse block is burned - that's probably where the smoke and smell came from. Voltage at the primary wire is 7V. Voltage across that resistor (whether or not it is isolated) is 7V (same as battery). Now, when I test the old original resistor on the bench, I get the same readings for voltage and continuity. Of course, I do not know if that resistor ever worked. I had checked the ignition switch, but I will go back through it as suggested by supereal. This is a contemplative hobby.

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