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Discussion Starter · #1 ·
My 1988 dodge has 6.5 volts on the pos side of coi, and 1.5 on the neg side of. There shouldnt be any voltage to the neg side of thr coil.
 

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Welcome to Allpar. What model and which engine?
If you are testing for spark, this may not be a valid test.
 

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. . . My 1988 dodge has 6.5 volts on the pos side of coi, and 1.5 on the neg side of. . . . .
If you have 6.5 volts on the coil positive terminal, that would indicate you have a V8 engine with carburetion??? A 1988 engine with carburetion ( no electronic fuel injection) would use a ballast resistor in series with the power feed to the coil. Twelve (12) volts only is present on the positive coil terminal when the ignition key switch is in the START position and the starter relay is energized.

. . . There shouldnt be any voltage to the neg side of thr coil. . . . .
Your thinking on this is incorrect. If there is voltage at the positive terminal of the coil, there will be voltage on the negative terminal. No voltage would indicate an open circuit in the primary winding of the coil and the engine would not run and have spark. The voltage is lower on the negative terminal because the primary winding of the coil has resistance which results in lower voltage when measured at the negative terminal.

With starter engaged are you getting any spark between a spark plug cable end and the plug?
 

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My 1988 dodge has 6.5 volts on the pos side of coi, and 1.5 on the neg side of. There shouldnt be any voltage to the neg side of thr coil.
It sounds like you may be using a voltmeter on the coil while cranking, which is NOT a valid test. The response of voltmeters is not fast enough to get an accurate reading of the changing voltage as the coil switches on and off.
To diagnose the coil, measure its primary and secondary resistances. From + to - terminal (primary resistance), it should be between about 0.5 and 1.8 ohms. From + terminal to output (tower terminal, secondary resistance), you should get between about 6,000 and 15,000 ohms. If either reading is zero or infinity, the coil is shorted or open. If the readings are normal, look elsewhere.

Did you check fault codes? This should always be the first step in diagnosis.
 
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Discussion Starter · #5 ·
It sounds like you may be using a voltmeter on the coil while cranking, which is NOT a valid test. The response of voltmeters is not fast enough to get an accurate reading of the changing voltage as the coil switches on and off.
To diagnose the coil, measure its primary and secondary resistances. From + to - terminal (primary resistance), it should be between about 0.5 and 1.8 ohms. From + terminal to output (tower terminal, secondary resistance), you should get between about 6,000 and 15,000 ohms. If either reading is zero or infinity, the coil is shorted or open. If the readings are normal, look elsewhere.

Did you check fault codes? This should always be the first step in diagnosis.
No there is not faut codes for my truck. I wish there where.
 

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Discussion Starter · #6 ·
[The ohom TE="wormwoman, post: 1085256485, member: 112120"]
No there is not faut codes for my truck. I wish there where.
[/QUOTE] the coil showed 6.0 on the pos side and 1.5 on the neg side with the key on.
 

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Discussion Starter · #7 ·
If you have 6.5 volts on the coil positive terminal, that would indicate you have a V8 engine with carburetion??? A 1988 engine with carburetion ( no electronic fuel injection) would use a ballast resistor in series with the power feed to the coil. Twelve (12) volts only is present on the positive coil terminal when the ignition key switch is in the START position and the starter relay is energized.



Your thinking on this is incorrect. If there is voltage at the positive terminal of the coil, there will be voltage on the negative terminal. No voltage would indicate an open circuit in the primary winding of the coil and the engine would not run and have spark. The voltage is lower on the negative terminal because the primary winding of the coil has resistance which results in lower voltage when measured at the negative terminal.

With starter engaged are you getting any spark between a spark plug cable end and the plug?
Still no help with checing the spark plug firing while i turn the motor over. Im trying to get someone to help me with that. Or they dont want to listen to what i need them to do, in order to folow your instructions. So im still stuck.
 

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Discussion Starter · #8 ·
Still no help with checing the spark plug firing while i turn the motor over. Im trying to get someone to help me with that. Or they dont want to listen to what i need them to do, in order to folow your instructions. So im still stuck.
I think the starter rely comes before the balister, te ake the flip flop, with the ecm to make them both, start and run.
 

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Discussion Starter · #9 ·
No there is not faut codes for my truck. I wish there where.
Update on what I have found. There is no spark from the plug wire, to plug. With key on the coil ohms at 5 on pos side, 1.5 on neg side. When I crank the truck, the meter drops ohms down to 4 on pos side, neg drops to 1 on neg side. Should I try to gap the dual pick up on the disturbor?
 

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You cannot measure resistance this way - this is a faulty technique and will likely damage the electronics.
You never answered what engine this is.
Which plug wire has no spark?
 
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Discussion Starter · #11 ·
Update on what I have found. There is no spark from the plug wire, to plug. With key on the coil ohms at 5 on pos side, 1.5 on neg side. When I crank the truck, the meter drops ohms down to 4 on pos side, neg drops to 1 on neg side. Should I try to gap the dual pick up on the disturbor?
You cannot measure resistance this way - this is a faulty technique and will likely damage the electronics.
You never answered what engine this is.
Which plug wire has no spark?
360motor or a 5.9 Manual transmission, with a dual coil pick-up. Imchecking my fireing orde r
 

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the plug we checkedwas first plug on front right side of motor. So number 1
If by 'right side', you mean the passenger side, that is plug number 2. Typically, the driver's side is called the left side, and the passenger side called the right side, as referenced from the position seated behind the wheel - NOT looking head-on while standing in front of the vehicle. So the driver's side cylinders are 1, 3, 5, 7, and the passenger side are 2, 4, 6, 8.
Firing order for this engine is 1-8-4-3-6-5-7-2, going clockwise.

I suggest again, measuring the coil resistance correctly. That means, with engine and key off, measure ohms between + and - terminals of the coil, should be about 0.6 or so ohms to about 1.4 ohms. Measure from the + terminal to the center tower contact, should be between about 9K ohms and 15K ohms.
 

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Discussion Starter · #14 ·
Ok her
the plug we checkedwas first plug on front right side of motor. So number 1
When u told me to check the Pos terminal to center tower contact . I took that to mean that was the center of the coil , should I have used the center of the disturbor. With the key off the pos to neg ohm meter read 1.6 ohms. Then I trie to get a reading from both, I got no reading at all. I"ll recheck the second step again when u tell me which tower to use for this reading. Thank u so much for helping me.
 

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Ok her

When u told me to check the Pos terminal to center tower contact . I took that to mean that was the center of the coil , should I have used the center of the disturbor. With the key off the pos to neg ohm meter read 1.6 ohms. Then I trie to get a reading from both, I got no reading at all. I"ll recheck the second step again when u tell me which tower to use for this reading. Thank u so much for helping me.
Not sure what you mean about a reading from both.
The primary reading sounds close enough to be good.
The secondary resistance is measured from the positive terminal to the center terminal of the coil. Unplug the coil wire and take this measurement with key off. If it's between about 9K and 15K ohms, the coil is good and is not suspected.
Do not take resistance measurements with key on, this will short out circuitry through the meter.
 

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Discussion Starter · #16 ·
Ok her

When u told me to check the Pos terminal to center tower contact . I took that to mean that was the center of the coil , should I have used the center of the disturbor. With the key off the pos to neg ohm meter read 1.6 ohms. Then I trie to get a reading from both, I got no reading at all. I"ll recheck the second step again when u tell me which tower to use for this reading. Thank u so much for helping me.
Not sure what you mean about a reading from both.
The primary reading sounds close enough to be good.
The secondary resistance is measured from the positive terminal to the center terminal of the coil. Unplug the coil wire and take this measurement with key off. If it's between about 9K and 15K ohms, the coil is good and is not suspected.
Do not take resistance measurements with key on, this will short out circuitry through the meter.
Thank u I"l be su
ure to remember that hint. The pos term to the coil tower the ohm reading was 9.3. for this . Before I forget, the plug w checked for spark was #1 plug. and we had no spark.
 

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Discussion Starter · #17 ·
So any idea where I mite try to checknext. The only electric part for the ing system i have not changed would be the key switch, and starter relay, maybe the flip flop in the relay, aint flipping. Ive been with
 

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Check the # on the relay. Most Mopars have several relays with the same #. IF yours does, swap the starter relay with another KNOWN GOOD one with the same # and see if that works. When you say the flip flop in the relay, I'm guessing you're referring to the contacts. You can open a relay and lightly sand the contacts and make it work again.
 

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Thank u I"l be su
ure to remember that hint. The pos term to the coil tower the ohm reading was 9.3. for this . Before I forget, the plug w checked for spark was #1 plug. and we had no spark.
9.3 ohms? Or 9.3K ohms? One is failed, one is normal.
 
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