Car won't start - No spark - No voltage at Coil
#582456
01/14/10 06:09 PM
01/14/10 06:09 PM
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Joined: Jul 2008
Posts: 157 California
dg_dodge
OP
member
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OP
member
Joined: Jul 2008
Posts: 157
California
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Hi guys, This past weekend my 1970 Challenger finally pulled it's first "no start" on me (after 5+ trouble free years). I went to fire it up and it just cranked and cranked .. Checked for fuel and it was fine. Took off the distributor cap and verified the rotor was turning. Checked for spark at the distributor-to-coil wire - nothing. I then swapped out the ballast resistor to a brand new one I had - still no spark. Finally, I put a multimeter to the coil and checked for voltage with the key both in the "run" position and while cranking - zero voltage both ways. I know very little about electrical problems, so I'm not sure what to try next? Could the coil or ECU (Mopar Orange) box be bad? Or something earlier upstream like the ignition switch or bulkhead piece? If so, how to test these things? The car has started so reliably in the past that it surprised me something could have just gone dead without going flakey first, but I guess anything can happen.. Any tips on what to check next would be greatly appreciated! Thanks much!
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Re: Car won't start - No spark - No voltage at Coil
[Re: OzHemi]
#582464
01/14/10 07:59 PM
01/14/10 07:59 PM
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Joined: Aug 2007
Posts: 6,095 Valencia, España
NachoRT74
master
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master
Joined: Aug 2007
Posts: 6,095
Valencia, España
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take in mind the yellow and red wires ilustrated on this diagrams are slightly incorrect for pre 75/76 cars.
First, yellow wire is really brown and doesn't come from starter relay, comes from ign switch
Second, red wire going to coil is brown OR blue ( depending of year )
the yellow wire coming from starter relay is JUST CORRECT for laters cars where the starter relay provides the ballast bypass instead coming directly from ign switch. Is a very diff starter relay setup
With a Charger born in Chrysler assembly plant in Valencia, Venezuela
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Re: Car won't start - No spark - No voltage at Coil
[Re: OzHemi]
#582468
01/14/10 09:31 PM
01/14/10 09:31 PM
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Joined: Nov 2003
Posts: 36,040 Lincoln Nebraska
RapidRobert
Circle Track
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Circle Track
Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
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most likely bad orange box. Check that it didnt lose it's ground. then take off the wire to the coil negative primary terminal and with a jumper wire with an alligator clip on each end, clip one end of the jumper to this coil (pri-) terminal and repeatedly touch the other end alligator clip to ground repeatedly like Morse Code & see if the large coil to dist secondary wire (the dist end) held 1/4" from ground sparks (Check with key "on" and key in "start") If it (large coil wire) sparks (in both positions) that only leaves the dist pickup (not likely) and the orange box (most likely). If it doesn't spark in both positions do Nachos voltage checks to find the open (check/clean the firewall bulkheads 1st) and take all (3) wires (2 small 1 large) off of the coil & w your multimeter see if the pri and sec sides of the coil have continuity. What coil and what ballast are you using?
Last edited by RapidRobert; 01/14/10 09:33 PM.
live every 24 hour block of time like it's your last day on earth
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Re: Car won't start - No spark - No voltage at Coil
[Re: dg_dodge]
#582470
01/14/10 10:21 PM
01/14/10 10:21 PM
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Joined: Nov 2003
Posts: 36,040 Lincoln Nebraska
RapidRobert
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Circle Track
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Posts: 36,040
Lincoln Nebraska
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I was thinking if you have a high powered coil w a lower ohm ballast that they would be more likely to fail but from your descrip that's not the case here. Take ALL wires off of the coil(-) pri terminal to do the test (your 2nd wire is most likely a tach rpm sensing wire). The bulkheads: some have a wire bail like a master cyl cover & if so take it off or flip it over & you'll see the nubs on the ends of the black bulkhead that hold them on. Depress them inward & wiggle the connector off.
live every 24 hour block of time like it's your last day on earth
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Re: Car won't start - No spark - No voltage at Coil
[Re: strokin73cuda]
#582473
01/14/10 11:05 PM
01/14/10 11:05 PM
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Joined: Nov 2003
Posts: 36,040 Lincoln Nebraska
RapidRobert
Circle Track
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Circle Track
Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
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Clean the terminals on the half you pull off w a small bristle brush and the firewall half terminals w an extra seperate male terminal or a small eyeglass screwdriver (be conservative, only need to scrape some fresh brass lines)not open them up any then yes hit it w your spray cleaner.
live every 24 hour block of time like it's your last day on earth
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Re: Car won't start - No spark - No voltage at Coil
[Re: dg_dodge]
#582475
01/14/10 11:23 PM
01/14/10 11:23 PM
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Joined: Dec 2003
Posts: 5,314 Carstairs, Alberta, Canada
dave571
master
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master
Joined: Dec 2003
Posts: 5,314
Carstairs, Alberta, Canada
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Quote:
Hi guys,
This past weekend my 1970 Challenger finally pulled it's first "no start" on me (after 5+ trouble free years). I went to fire it up and it just cranked and cranked ..
Checked for fuel and it was fine. Took off the distributor cap and verified the rotor was turning. Checked for spark at the distributor-to-coil wire - nothing. I then swapped out the ballast resistor to a brand new one I had - still no spark.
Finally, I put a multimeter to the coil and checked for voltage with the key both in the "run" position and while cranking - zero voltage both ways.
I know very little about electrical problems, so I'm not sure what to try next? Could the coil or ECU (Mopar Orange) box be bad? Or something earlier upstream like the ignition switch or bulkhead piece? If so, how to test these things?
The car has started so reliably in the past that it surprised me something could have just gone dead without going flakey first, but I guess anything can happen..
Any tips on what to check next would be greatly appreciated!
Thanks much!
You are giving yourself too little credit. You have found there is no power at the coil.
THAT is what is wrong. The coil needs power to operate.
If you were using a trouble shooting chart the next step would be "repair circuit, and retest".
Put the key in run, and physically follow the wire back from the coil using a test light (NOT a meter) checking at all the connectors until it lights up.
As said, bulkhead is a common spot. I've seen the connector for the ignition switch burn up too.
The reason I say not the meter, is the meter can be inaccurate in a situation like this, as it does not put load on the circuit. You can still have voltage, but not enough current capacity for anything to work. Can be great for making you chase your head up your... u know.
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