no spark
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Hello,
I Hope your holiday is better than mine.
Thx frank
Ok found a ballast resistor hanging out of the harness between the driver fender and motor. Removed that resistor and did not connect the wire from the harness together, then ohm it, and it read 21,978 ohms. Diagram says 22K ohms. I tried to start the truck and it started without that ballast resistor, and circuit open. I also found under the tape that the white wire is not connect, look at Ardwrkntrk thoughtful and helpful diagram, which would make half sense if there is no ballast resistor.
Then I installed that resistor in series with the coil, and truck will not start with resistor in.
So is there another resistor somewhere? Could the #F102 ignition have a Ballast resistor built inside? Could the coil # C839VC not require a ballast resistor?
I know not enough information. I have to go back and do some voltage testing, but if someone has something helpful you may speak or type.
thx
I Hope your holiday is better than mine.
Thx frank
Ok found a ballast resistor hanging out of the harness between the driver fender and motor. Removed that resistor and did not connect the wire from the harness together, then ohm it, and it read 21,978 ohms. Diagram says 22K ohms. I tried to start the truck and it started without that ballast resistor, and circuit open. I also found under the tape that the white wire is not connect, look at Ardwrkntrk thoughtful and helpful diagram, which would make half sense if there is no ballast resistor.
Then I installed that resistor in series with the coil, and truck will not start with resistor in.
So is there another resistor somewhere? Could the #F102 ignition have a Ballast resistor built inside? Could the coil # C839VC not require a ballast resistor?
I know not enough information. I have to go back and do some voltage testing, but if someone has something helpful you may speak or type.
thx
pedant
Joined: Jan 2008
Posts: 23,576
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From: EXTREME southwest CT
That's great, the coil tests good.
The white wire sends a signal to the ignition module to retard the ignition timing 13* while cranking. (to reduce load on the starter)
There should be a resistor wire already built into the harness of all gasoline trucks in this era.
In my 1987 it is a thick wire right down by the ignition switch at the bottom of the steering column.
Everyone seems to agree that it is a thick pink or red wire, but I can't say with absolute certainty it is in the same location in your 1986 body style.
IIRC this wire should ideally have 1.3 ohm resistance. (1.25-1.35 acceptable)
All Duraspark 2 systems use this reduced voltage in 'run' to keep the coil windings from overheating.
The white wire sends a signal to the ignition module to retard the ignition timing 13* while cranking. (to reduce load on the starter)
There should be a resistor wire already built into the harness of all gasoline trucks in this era.
In my 1987 it is a thick wire right down by the ignition switch at the bottom of the steering column.
Everyone seems to agree that it is a thick pink or red wire, but I can't say with absolute certainty it is in the same location in your 1986 body style.
IIRC this wire should ideally have 1.3 ohm resistance. (1.25-1.35 acceptable)
All Duraspark 2 systems use this reduced voltage in 'run' to keep the coil windings from overheating.
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From: Virginia
I assumed you already had the resistor and where using it, since your voltage was around 9v to the coil. To make sure, get the engine running and check the voltage again at the coil. It should be around 9 or so, not 12-14 like the rest of the truck.
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Hi,
I just found that resistor today frank, I don’t know why the voltage was 9 volt, maybe weak battery. I don’t know Maybe it’s the wrong one, but it ohm to 22k like the ford dealer book says, engine/ emission diagnosis volume H- page 20-15, and 21-229. Tomorrow I will look at steering column and trace out pin 4.
thx
I just found that resistor today frank, I don’t know why the voltage was 9 volt, maybe weak battery. I don’t know Maybe it’s the wrong one, but it ohm to 22k like the ford dealer book says, engine/ emission diagnosis volume H- page 20-15, and 21-229. Tomorrow I will look at steering column and trace out pin 4.
thx
Moderator
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From: Denver Metro Area, CO
You're in the entirely wrong section of the book; you are in the EEC-IV Computer section, you need to be Section 15 - Ignition Systems, Timing Procedures and Diagnostics.
Pages 15-24 and 15-25 look like they might be of interest to you, as do many of the following pages....
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Hi ctubutis,
Thx that was very helpful.
And of course thank you Dave and Frank.
Ok while it is running I read 3.5 to 8 volts at coil batt and tach. My meter is going wacko do to the on and off voltage. I also read from batt to a good ground just under 13 volts. I am going to drop the steering column and find that wire.
thx
Thx that was very helpful.
And of course thank you Dave and Frank.
Ok while it is running I read 3.5 to 8 volts at coil batt and tach. My meter is going wacko do to the on and off voltage. I also read from batt to a good ground just under 13 volts. I am going to drop the steering column and find that wire.
thx
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From: Virginia
It looks close to being right. Your battery voltage is a little low, but that might from you messing around with it cranking it alot. That would also explain the 8v at the coil, it should run on that. You really can't do any checking on the tach side with the engine running.
The resistor you are looking for is around 1.1 ohm and it's a special section of wire in the harness.
If you are using the green/red or red/green wire to the coil +, you are probably ok and are using the resistance wire like you should be. If you are using the blue/white or white/blue(I can't keep these colors straight in my head) then that will be the wrong wire, that's the one they used with the TFI coil with no resistor.
The resistor you are looking for is around 1.1 ohm and it's a special section of wire in the harness.
If you are using the green/red or red/green wire to the coil +, you are probably ok and are using the resistance wire like you should be. If you are using the blue/white or white/blue(I can't keep these colors straight in my head) then that will be the wrong wire, that's the one they used with the TFI coil with no resistor.
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