Ideas? 460 No Spark
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Ideas? 460 No Spark
I've been trying to solve this problem all week and I'm sure I'm just missing something simple...
1976 F-250 Crew Cab, 460, C-6. Died just like you shut the key off. I have no spark. Using the Ford Shop Manual I have gone through the entire trouble-shooting procedure and my pick-up coil checked out of specs. Installed new pick-up coil, still no spark. As part of regular maintenance and continuing upgrades the following have been replaced in the last couple of months: plugs, plug wires, cap, rotor. Wiring harness to coil was looking a bit ratty so a few weeks ago I stripped all the old wrapping off and re-wrapped it from one end to the other. Also replaced the module with a new unit.
What am I missing?
Oh, nearly forgot this: also removed the ignition switch and proved it out using the Shop Manual procedures. Passed with flying colors...
1976 F-250 Crew Cab, 460, C-6. Died just like you shut the key off. I have no spark. Using the Ford Shop Manual I have gone through the entire trouble-shooting procedure and my pick-up coil checked out of specs. Installed new pick-up coil, still no spark. As part of regular maintenance and continuing upgrades the following have been replaced in the last couple of months: plugs, plug wires, cap, rotor. Wiring harness to coil was looking a bit ratty so a few weeks ago I stripped all the old wrapping off and re-wrapped it from one end to the other. Also replaced the module with a new unit.
What am I missing?
Oh, nearly forgot this: also removed the ignition switch and proved it out using the Shop Manual procedures. Passed with flying colors...
Postmaster
Joined: Mar 2011
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From: Taxachusetts
I'll bet its your ICM. New ones have been know to exhibit the symptoms you describe. Motorcraft ICMs are the best. Do you have the DuraSpark ll with the blue grommet on the ICM?
To test the ICM - Hook up a test light to the "tach" terminal on the coil, the other to ground. Have someone crank it from the key switch. The light should be always on when not cranking, blinking when cranked. This will let you know the ICM is firing the coil...and the ICM and pickup module are fine.
Stator check: separate the dizzy connector from the harness - ohm out the stator resistance across the orange and purple diizzy connections. If it reads between 400 and 1K ohms, you're good to go. Anything < 400 ohms or > 1K ohms, the stator assembly went south.
To test the ICM - Hook up a test light to the "tach" terminal on the coil, the other to ground. Have someone crank it from the key switch. The light should be always on when not cranking, blinking when cranked. This will let you know the ICM is firing the coil...and the ICM and pickup module are fine.
Stator check: separate the dizzy connector from the harness - ohm out the stator resistance across the orange and purple diizzy connections. If it reads between 400 and 1K ohms, you're good to go. Anything < 400 ohms or > 1K ohms, the stator assembly went south.
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I forgot to mention I tried replacing the coil and the module with known good units. When I re-wrapped the wiring harness I changed the horseshoe connector on the coil.
I DID try the 'blink test' with a test light. The light doesn't blink with either coil or module installed. Like I said, I've run through the entire troubleshooting section in the manual. All the tests say I should have spark now, but I don't.
I DID try the 'blink test' with a test light. The light doesn't blink with either coil or module installed. Like I said, I've run through the entire troubleshooting section in the manual. All the tests say I should have spark now, but I don't.
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Yes, first thing I did. I've had the roll pin shear on a distributor before.
Postmaster
Joined: Mar 2011
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From: Taxachusetts
Since the "blink test" showed no "blink," I would re check the distributor cap and rotor, plug wires and the wire between the coil and distributor. I know you said they're new but, as you stated before, it could be something as simple as that.
You didn't notice any frayed/shot insulation on the wires you re-wrapped or a lousy/frayed connection on the horseshoe connection, did you? I know you said you've checked and rechecked, so please forgive a grumpy old fart for asking for repeated tests....
You didn't notice any frayed/shot insulation on the wires you re-wrapped or a lousy/frayed connection on the horseshoe connection, did you? I know you said you've checked and rechecked, so please forgive a grumpy old fart for asking for repeated tests....
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Laughing Gas
Joined: Apr 2016
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From: Buffalo NY
If the light doesn't blink, and you tried a modulator and coil that you know are good,it appears that there is no signal coming from the distributor. Does the new pick-up coil check good(including ground)? Is the wiring between the dist. and module ok?
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Posting Guru
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Thanks for the replies, guys. I didn't get to work on it today; other ranch chores took precedent. I'm planning on starting back at square one with the manual again. I'll check back in afterwards.
Laughing Gas
Joined: Nov 2013
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From: S.E. Louisiana;so far USA
Watch for corrosion within the "plug together" connectors, especially on vehicles which do not have inside storage. The corrosion can create high resistance connections, some of which can be intermittent. 
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Okay, got a chance to get back on this today. I totally unwrapped, inspected, and repaired a couple of wires on the engine wiring harness. Still no go.
I got out the manual again, and started the procedures all over. When I did this the other day, I could swear I had voltage at Pin 3 (orange wire). I don't now. And, I can't for the life of me figure out where this darn wire gets power. It disappears into the main harness and I can't find where it goes. Does anybody know if this wire goes to the key switch or to the 'I' terminal on the solenoid? I had a harness from a '77 in storage to look at, but Ford changed the color scheme between the two year models. Thanks, Ford...
I quit drinking fifteen years ago, but I'm seriously thinking about starting again...
I got out the manual again, and started the procedures all over. When I did this the other day, I could swear I had voltage at Pin 3 (orange wire). I don't now. And, I can't for the life of me figure out where this darn wire gets power. It disappears into the main harness and I can't find where it goes. Does anybody know if this wire goes to the key switch or to the 'I' terminal on the solenoid? I had a harness from a '77 in storage to look at, but Ford changed the color scheme between the two year models. Thanks, Ford...
I quit drinking fifteen years ago, but I'm seriously thinking about starting again...
Laughing Gas
Joined: Nov 2013
Posts: 1,207
Likes: 60
From: S.E. Louisiana;so far USA
Okay, got a chance to get back on this today. I totally unwrapped, inspected, and repaired a couple of wires on the engine wiring harness. Still no go.
I got out the manual again, and started the procedures all over. When I did this the other day, I could swear I had voltage at Pin 3 (orange wire). I don't now. And, I can't for the life of me figure out where this darn wire gets power. It disappears into the main harness and I can't find where it goes. Does anybody know if this wire goes to the key switch or to the 'I' terminal on the solenoid? I had a harness from a '77 in storage to look at, but Ford changed the color scheme between the two year models. Thanks, Ford...
I quit drinking fifteen years ago, but I'm seriously thinking about starting again...
I got out the manual again, and started the procedures all over. When I did this the other day, I could swear I had voltage at Pin 3 (orange wire). I don't now. And, I can't for the life of me figure out where this darn wire gets power. It disappears into the main harness and I can't find where it goes. Does anybody know if this wire goes to the key switch or to the 'I' terminal on the solenoid? I had a harness from a '77 in storage to look at, but Ford changed the color scheme between the two year models. Thanks, Ford...
I quit drinking fifteen years ago, but I'm seriously thinking about starting again...
It's like W. C. Fields said about his ex-wife. "That woman drove me to drink. It's the one thing I'll always be indebted to her for." Perhaps the truck can also help this way.
Postmaster
Joined: Mar 2011
Posts: 2,698
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From: Taxachusetts
The green wire runs from the module to the TACH or minus coil terminal. This is where you can connect a normal tachometer. The orange and purple wires from the module run to the pickup inside the distributor.
Postmaster
Joined: Mar 2011
Posts: 2,698
Likes: 7
From: Taxachusetts
To check ICM to coil: Disconnect the four wire connector from the ICM and the horseshoe connector from the coil. Measure the resistance from the "TACH" termnial on the horseshoe connection to ground. If you're reading > 100 ohms the ICM went south. < 100 ohms, check the wiring harness between the ICM and coil.
I couldn't post up a better picture in my last post. Too many characters, they say. That's why the picture didn't insert or "click to open" didn't work.
I think that gremlins have invaded somewhere....or its late (for me) hahaha
I couldn't post up a better picture in my last post. Too many characters, they say. That's why the picture didn't insert or "click to open" didn't work.
I think that gremlins have invaded somewhere....or its late (for me) hahaha