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Starting issue
#11
(04-05-2019, 07:12 AM)boilermaster Wrote: jpaz, 
sounds to me like your ignition is capable of firing in the run mode but not in the crank mode.
They are 2 different circuits.
your results are all based on how the car was tested, when you are jumping the solenoid with the key in the run position you are not testing the crank circuit.
You need to test the crank circuit.
check for spark while someone is actually cranking the engine using the ignition switch (key) and Not jumping the starter solenoid.
You will find you have spark in run and no spark in crank.
Spark in the CRANK circuit is provided by the I terminal of the starter relay, first thing, you need to have voltage on that terminal while cranking, then you need to have voltage to the coil positive while cranking, will check the 1972 wiring guide and give you circuit number, color and splice location.
Boilermaster

I think they did check it like the way you said. So yes, no spark in the crank position, but spark in the run position. I just am not sure if this is always the case. I don’t have my car here, it’s still at the shop. Sorry, but I’m probably missing some information to give you. Electrical is definitely not my forte. Thanks,
                           John

run_horse Run Horse Run!
John 72 Q Code
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#12
jpaz,
Circuit 16A is ignition feed for crank mode  c 9 at starter relay, Red/ light green
Circuit 16 is ignition feed for run mode also Red/ light green
they are connected at C-14 (believe it is under the dash near steering column ignition switch.
16 a supplys battery voltage to the positive side of the ignition coil while the engine is being cranked
circuit 16 provnides about 9 volts to the positive side of the ignition coil while the ignition switch is in the RUN mode.
So you need to see 12 volts at C14 while cranking and about 9 volts at C14 while the key is in the run position.
Because the engine runs when you jump the starter relay, that tells me that circuit 16 is ok.
When you crank the engine there needs to be 12 volts at the positive side of the ignition coil BECAUSE the ignition switch does NOT provide any voltage to circuit 16 while the engine is cranking.
really sounds to me that you have no voltage being supplied to 16A out of the starter relay or 16A is open from the starter relay to C14.
you could have got the wrong or defective relay or the 2 push on terminals at the relay could be crossed up too.
Boilermaster
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#13
(04-04-2019, 10:23 PM)Hemikiller Wrote: Since they had the whole car apart and engine out, verify you have a proper battery (-)  -> fender apron ->  block ground cable. If this is not done properly, or is missing the fender apron ground, you'll have all sorts of odd electrical issues.

I’m pretty sure they checked that out first, but will make sure. I even added two other grounds, one from back of block to firewall and one from front of block to frame. I was having some weird electrical issues so I did this a couple years ago. Definitely made a difference.

run_horse Run Horse Run!
John 72 Q Code
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#14
boilermaster pid=' dateline=\'1554468295' Wrote:jpaz,
Circuit 16A is ignition feed for crank mode  c 9 at starter relay, Red/ light green
Circuit 16 is ignition feed for run mode also Red/ light green
they are connected at C-14 (believe it is under the dash near steering column ignition switch.
16 a supplys battery voltage to the positive side of the ignition coil while the engine is being cranked
circuit 16 provnides about 9 volts to the positive side of the ignition coil while the ignition switch is in the RUN mode.
So you need to see 12 volts at C14 while cranking and about 9 volts at C14 while the key is in the run position.
Because the engine runs when you jump the starter relay, that tells me that circuit 16 is ok.
When you crank the engine there needs to be 12 volts at the positive side of the ignition coil BECAUSE the ignition switch does NOT provide any voltage to circuit 16 while the engine is cranking.
really sounds to me that you have no voltage being supplied to 16A out of the starter relay or 16A is open from the starter relay to C14.
you could have got the wrong or defective relay or the 2 push on terminals at the relay could be crossed up too.
Boilermaster

Thanks boilermaster, I’ll have to see exactly how much of the circuit they tested. 
The one thing that I’m wondering about is that the coil that was in the car at the time of the accident went bad. It didn’t get hit or physically damaged, but it wouldn’t work when they were starting engine on their engine run stand.

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John 72 Q Code
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#15
Ok, I just checked with the shop and they have checked everything you guys recommended and they think there’s a bad spot in a wire somewhere that fails intermittently. I guess I’ll just have to track it down when I get the car back.
Thanks for all the replies, I really appreciate all the help and info you guys provide.

run_horse Run Horse Run!
John 72 Q Code
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#16
(04-05-2019, 11:18 AM)jpaz Wrote: Ok, I just checked with the shop and they have checked everything you guys recommended and they think there’s a bad spot in a wire somewhere that fails intermittently. I guess I’ll just have to track it down when I get the car back.
Thanks for all the replies, I really appreciate all the help and info you guys provide.

Send your harness to Midlife and get it refurbed.

Steve
1971 Grandé
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#17
jpaz,
Here is a simple test you can try to determine if the ignition crank circuit is good or not.
disconnect the ignition coil wire POSITIVE, with the key in the run position.  in the RUN position measure the voltage at the coil positive that you just disconnected and record the voltage (should be around 9 volts dc.
With that lead still disconnected now remove the I lead at the starter relay, it too should read about 9 volts dc (if the splice/connector is good).
The starter relay is designed to do 2 things, supply the starter with voltage when the key in the crank position AND supply the ignition with voltage while in the crank position.
the starter is supplied with voltage thru the S terminal when in the key is in the crank position and the ignition is supplied voltage thru the I terminal of the starter relay when the key is in the crank position.
No voltage out of the I terminal of the starter relay = no voltage to the ignition while in the crank position.
The ignition switch does NOT supply the ignition coil with voltage while it is in the crank position, that is the starter relay's I terminals job.
Whenever the starter relay is energized, sending voltage to the starter (S TERMINAL ) it should be also sending voltage to the ignition coil positive wire
thru the starter relay I terminal.
Boilermaster
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#18
(04-05-2019, 12:20 PM)boilermaster Wrote: jpaz,
Here is a simple test you can try to determine if the ignition crank circuit is good or not.
disconnect the ignition coil wire POSITIVE, with the key in the run position.  in the RUN position measure the voltage at the coil positive that you just disconnected and record the voltage (should be around 9 volts dc.
With that lead still disconnected now remove the I lead at the starter relay, it too should read about 9 volts dc (if the splice/connector is good).
The starter relay is designed to do 2 things, supply the starter with voltage when the key in the crank position AND supply the ignition with voltage while in the crank position.
the starter is supplied with voltage thru the S terminal when in the key is in the crank position and the ignition is supplied voltage thru the I terminal of the starter relay when the key is in the crank position.
No voltage out of the I terminal of the starter relay = no voltage to the ignition while in the crank position.
The ignition switch does NOT supply the ignition coil with voltage while it is in the crank position, that is the starter relay's I terminals job.
Whenever the starter relay is energized, sending voltage to the starter (S TERMINAL ) it should be also sending voltage to the ignition coil positive wire
thru the starter relay I terminal.
Boilermaster

The problem is with the crank position. Sometimes there’s power to the coil, and sometimes not. They are sure that the problem is with that circuit. It’s just that it’s very intermittent. I will see if they tried this too. Will probably have to wait till next week to find out more.
Thanks again boilermaster.

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John 72 Q Code
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#19
My 48 year old wiring was falling to pieces inside the engine bay when i removed the engine and disturbed the wiring

Steve
1971 Grandé
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#20
(04-06-2019, 07:07 AM)Pegleg Wrote: My 48 year old wiring was falling to pieces inside the engine bay when i removed the engine and disturbed the wiring

I don’t have that problem.....yet. My issues are from the accident I was in.

run_horse Run Horse Run!
John 72 Q Code
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