I picked up this non runner, trying to get it going. I just replaced the starter and starter relay. It will crank (slowly) but the cable to the starter shows no resistance to grnd (-batt) when disconnected from the relay. I checked the cable its good. The + side of coil also shows no resistance to ground. I disconnected all the wires to the alternator thinking maybe I had hooked up wrong but get the same thing. I chased this around today and only succeded in confusing myself. I need some suggestions on how to track this down. Thanks Chris
EDIT: I guessed I skipped a bunch of stuff.....Seems to me that you should first SEPARATE the IGNITION PROBLEM from the CRANKING PROBLEM. Disconnect the ignition and see how it cranks - it should crank fine - if not........ Check the voltage during cranking - if it goes real low you've likely got a BAD connection/ loose wire/ bad wire/ etc. After cranking - carefully check the connections - HIGH resistance will generate a bunch of HEAT (DON'T burn yourself!!!). FWIW the cables THEMSELVES can go bad - even if the ENDS look ok - you can get corrosion past the end under the insulation and not even know it. That's why you need to check cranking voltage at the battery, starter and solenoid. Clean the battery terminals. Battery cables TOO SMALL are also a possible problem - some replacement cables are pathetically small. If EVERYTHING checks out there - check the timing - pull the plugs make sure there's no mechanical binding elsewhere. Also check the MOTOR GROUND - engine to chassis and chassis to battery. Keep it SIMPLE - lastly - is the starter shimmed properly???? (I forget if Ford's were adjustable or not) Ignition switchs can also "go bad" over time - they can CARBON TRACK resulting in all sorts of ODD problems - double check that the igniton switch is good - carbon has high resistance (usually when it burns across bakelite housings anyways) so eliminate this by checking teh voltage at the switch - low voltage and voltage where it shouldn't be are ways to focus in on the problem.
I agree. What he said about the cable corrosion too. I have a 66 Galaxie. To get a complete ground on a non-unibody car, you should cover ALL the bases. I found this out the hard way when I slowly killed 3 alternators. Ground... battery to body battery to engine engine to body engine to chassis body to chassis The one that solved my problem was grounding engine to chassis. I had all of these others covered and never believed it would be a problem until I read an article about it once. I figured surely that between all of the other grounds it would have been covered. ....and Ford starters don't typically require shims. Could be a bad starter drawing too much current. Take it out and have it tested to find out how much current its drawing. Might be dragging.
Thanks HR, lemme rephrase my problem. the + terminal on the starter motor should be an open circuit when no cable is connected (at least the way I know it) mine shows that it is a ground (-). The coil wire should be open when the car is off and + when energized (car on) mine looks like a ground (-). I just dont get it......
Kidwired - that's not necessarily true. Using an ohm meter on cars can mislead you easily. Cars are "dirty" environments - DC switch arc and can give "false" readings (false in the sense that they show LOW OHMS aka dead short but are really NOT a DEAD SHORT) that's why I suggest you measure voltage. The LOW OHM reading (dead short) from the starter to ground is normal - you are reading across the brushes. The + bat reading LOW OHMS (shorted to ground) is also normal - likely due to the age of the ingnition switch. FWIW I just ran to the garage and double checked this - both read LOW OHMS (under 20 and 4 respectively) so I wouldn't SWEAT this - check VOLTAGE instead. This will keep your sanity in place!!! Some Old time mechanics would YELL at you for measuring with an OHM meter because they are so misleading. I would STILL disconnect anything you suspect and check for proper cranking speed - then if all is well - add in the ignition circuit - check voltages again - check alt/gen - check voltage. If you ARE checking voltage then we need to talk more!!! I think having the coil wires switched (at the solenoid) will make it HOT when you're off and COLD when you're cranking. Did you or the previous owner mess with the starter solenoid wires????? Any chance they are reversed??? Forgive me - I don't know the Ford ignitions all that well, but they're all basically the same.
HR, yeah ok now thats enlightening, like a punch in the head. RE: reading across the brushes. this makes total sense and I have wondered about this in similar situations. Ok thanks, I'll start from scratch w/ a clear head.
uhh...yeah...any electrical load that's big enough to do some work, like crank an engine or fire spark plugs, will have low resistance to ground.
I'll give it a shot. Resistance is how you measure how difficult it is for electricty to flow thru something. Plastic and glass and air have high resistance, copper wire has very low resistance. If you are trying to get electricity to do something, like make a motor turn, you need a lot of current to flow thru the motor. So, you need the motor to have low resistance. If it had high resistance, it could not conduct any current, so it couldn't do any work. So a motor will have a very low resistance, it will act like a short-circuit when you measure it with your ohm meter. The same thing applies to any electrical device. The primary winding on a coil has very low resistance, so that it can conduct enough current to cause the secondary side to generate the high voltage to fire a spark plug. A light bulb has a low resistance, so that a lot of current can flow thru it and make the filament glow white hot.
if you are un sure of how any thin works i can check it against the 67 i just finished restoring. http://www.jalopyjournal.com/forum/showthread.php?t=75942
I can wrap my head around that, thanks for that explanation squirrel.I get it now. and u didnt even make my head hurt. Slag, that is a suweet car! superfantabulous work. I just may hit you w/ a question if I need.
Squirrel does a nice explanation!!!! Can't tow a car with a string!!!! I realize we are all talking DC here, but just to add to the conversation - in DC you are basically measuring across the brushes, aramature and to ground - hence the "appearing" short. In AC (brushless of course) this would NOT be true. As for the Coil - pretty much the same thing - you are measuring across the coil. If you meausre from the + terminal to the - terminal you will measure a certain amount of resistance but when you measure from the + terminal to ground you will measure MORE since you are now across the majority of the coil's internal wires. Of course this ASSUMES your points are CLOSED which completes your circuit. IF the points are OPEN - you may STILL get some readings that can make sense or not - faulty ignition switch - goofed up wiring etc. Since you got this as a non runner - it's hard to make any assumptions that stuff is right. It may be a good bet to disconnect things you are suspicious of - and bench test as much as possible. Then hook it up being 100% sure it is right. Stick to the basics and keep with the simple stuff right now.
Just went round n round w/ this again today. I had left the batt charger on it last wk so I'd have a fresh charge. But batt was completely dead today. Hooked up the charger and it wouldnt come on. Disconnected the starter and the charger came on (its smarter than me). Checked the new starter relay and it was stuck closed (12.5v w/ key off on starter side). I wacked it and it went to .25v....great. Disconnected the alt. harness. jumped to the starter, it wont turn. disconnected it and checked from +batt to starter terminal 12 V!!? Am I still reading the brushes like this? Last wk I had tried to remove the ign switch to test it but stripped the grnd on the back of it so I replaced it today anyway. Ok so whats going on? w/ key off I put my voltmeter to the +batt and the coil. 12v?! Disconnect coil grnd and pos, check the ign coil wire and get 12v HELLO! the other end of my meter is on the PLUS batt terminal. WTF? ok so its a short, next step isolate it. So I disconnect the coil connector at the firewall and recheck from firewall to coil...no short. of so the short is in the cabin, I check the coil wire connector cabin side...no short. Hmmm so theres 4 wires on the coil harness, 2 to a sensor on the manifold, 1 ign coil, 1 grnd. Check for continuity between all the wires...none. so that means one of these wires is the short on the cabin side. meaning the col harness has to be connected to see the short on the cabin side. Start poking around under dash, frustrated, not enuff room. This is where I yank out the front seat and the instrument cluster. lol I check for damage or wear under the dash and removed some of the tape, I didnt see anything but must have moved something as now my coil grnd is gone....until I turn the key on, then my coil becomes a 12v grnd. just shoot me and push this car off a cliff.
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