No voltage to coil

[wing01]

My first post here on square body. Need some help. I did something stupid last night on my 84 K10. Was unhooking the battery and wrench slipped off positive terminal, hit core support. Sparks were a flyin. Pulled it off quick, no big deal, or so I thought. Wont start now. It cranks over but no fire. I now have no 12v to the red wire at the distributor. Checked fuses, they check out fine. I have 12v at the alternator, on the plug and at the back. It has the stock distributor with the esc. What did I fry to get no power at the red wire? I even tried running a jumper from the battery and it still wont start. I wonder if I have more than one problem. I plan to swap to an older distributor but i still need to figure out the other problem with the red wire. Any help is greatly appreciated.

Mitch

 

[PrairieDrifter]

check the fusible links down by the starter.

 

[350runner]

^^^this

Sent from the dust in front of you!

 

[chengny]

I now have no 12v to the red wire at the distributor.

But you do have power to the big red wire (with the boot/stud) at the alternator? That is weird - the part of the ignition switch that feeds the pink wire to the distributor primary is supplied by the same fusible link at the firewall JB as the big alternator red.

Even stranger is the fact that you get no spark with the BATT terminal on the distributor hot wired to the battery positive?

What's more, the purple wire to the starter solenoid is also fed by the same part of the ignition switch. And you can crank!


I would forget all the other stuff and just figure out why you get no spark with a hot wire to the distributor BATT terminal. Try checking the pink wire for continuity to ground - with it pulled off the distributor. And also check the BATT terminal for continuity to ground

 

[wing01]

Yes I have power at the back of the alt. at the stud. That confused me as to why nothing at the pink wire for the dist. A few minutes ago I found a wiring diagram that shows the pink wire power coming from the esc module. My truck is a 305 with the esc style distributor. I wonder if I cooked the esc module? Maybe thats why it wont start even with a jumper wire to the battery. Ive never had this style hei before so I'm learning. I think it needs to go. Thanks for all the replies. Keep em coming.

 

[Georgeb]

If you want to try bypassing the esc to see if it will run read this:

http://www.hotrodders.com/forum/byp...es-186491.html#/forumsite/20624/topics/186491

 

[chengny]

I wonder if I cooked the esc module? Maybe thats why it wont start even with a jumper wire to the battery.

That's what I'm thinking. If the guts of the distributor are shorted straight to ground, there will be no spark. These HEI systems are pretty much either on or off - they need 10 volts minimum to make any kind of spark. Even at around 10.5 the spark is yellow and feeble.


The ESC test/diagnostic procedure - refer to diagram at the bottom:


1984-86 MODELS

Engine Cranks But Will Not Start

Check for spark at at the ends of at least 2 spark plug wires using tester ST-125 or equivalent. If spark is observed, malfunction is not in ignition system.
If no spark is observed, disconnect 4 pin connector to distributor, connect jumper wire between pins A and C on distributor side of connector, Figs. 5, 6 and 7, and attempt to start engine. If engine starts, proceed to step 3. If engine does not start, proceed as follows:
Remove jumper wire and reconnect 4 pin connector to distributor. Turn on ignition and measure voltage at pins F and K of controller 10 pin connector. If voltage is less than 11.6 volts, check feed circuit and repair as needed.
Set voltmeter on 2 volt scale and measure voltage between pins J and K of 10 pin connector while cranking engine. If reading is .75 volts or greater, ESC system is satisfactory.
Set voltmeter on 2 volt scale and measure voltage between pins G and H of 10 pin connector while cranking engine. If reading is .20 volt or greater, controller is defective. If reading is less than .20 volt, pole piece is defective.
Stop engine and remove jumper wire from distributor.
Connect suitable high resistance test lamp between distributor TACH terminal and ground, then turn on ignition. If test lamp lights, proceed to step 6.
If lamp does not light at TACH terminal, connect lamp between BAT terminal and ground and turn on ignition. If lamp does not light, repair feed circuit to ignition.
Crank engine with test lamp connected between distributor TACH terminal and ground. If test lamp flickers, system is satisfactory.
If test lamp does not flicker as engine is cranked, connect lamp between BAT terminal and pin A on distributor side of 4 pin ESC connector, then tap on coil. If coil makes a clicking noise when tapped, pole piece is defective.
If coil does not click, remove distributor cap an disconnect and reconnect pole piece electrical connector. If coil still does not click when tapped, ignition module is defective.
Poor Engine Performance

Disconnect distributor 4 pin connector, connect pins A and C on distributor side of connector with jumper wire, and road test vehicle.
If engine performance is still poor, cause is not in ESC system. If proper engine performance is restored by disconnecting ESC controller from distributor, remove jumper wire, reconnect 4 pin connector and proceed to next step.
Disconnect 10 pin connector from ESC controller, inspect terminals for proper contact, shots and opens, repair as needed, then recheck system operation.
If problem persists, disconnect 10 pin connector and measure resistance between pins B and K in connector. Reading should be 98-99 Kohms.
If resistance is not as specified, disconnect electrical connector from knock sensor and measure resistance between sensor terminal and ground. If resistance is 98-99 ohms, repair wiring between knock sensor and controller. If resistance is not 98-99 Kohms, knock sensor is defective.
Reconnect 10 pin connector to controller and measure voltage between pins F and K with ignition on. If voltage reading is less than 11.6 volts repair feed circuit as needed.
Set voltmeter on 20 volt AC scale and measure voltage between connector pins H and K with ignition on. If reading is less than .20 volt, inspect system wiring and repair as needed. If reading is greater than .20 volt, ensure all connectors are properly seated, then road test vehicle. If problem persists, replace ESC controller.
Engine Detonation

Inspect connector and wiring to knock sensor and repair as needed.
Connect suitable spark advance tester to engine, run engine until it reaches normal operating temperature and set engine to run at a minimum of 1200 RPM, then observe ignition timing while tapping on exhaust manifold. If ignition timing retards when manifold is tapped, ESC system is operating properly.
Stop engine, disconnect 10 pin connector from ESC controller and measure resistance between pins B and K of connector. If resistance is not 98-99 ohms, proceed to step 5.
Measure resistance between pins H and K in connector. If resistance is 14-16 ohms, replace controller. If resistance is not 14-16 ohms, repair wiring to controller.
Disconnect electrical connector from knock sensor and measure voltage at sensor terminal with engine running at 2000 RPM. If reading is not .08 volt or more, knock sensor is defective.
Stop engine. If knock sensor voltage output is satisfactory, check wiring between knock sensor and terminal B of controller and between controller terminal K and ground and repair as needed.

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[wing01]

IT RUNS! Thanks guys for pointing me in the right direction. I jumped pins a & c and ran my jumper from the battery. Fired right up. So then I went to testing the pink wire or so i thought. The wire that was originally plugged to BAT on the dist. was still dead. I unplugged it again and pulled that wire up higher to see where it went. Its just a short pigtail down to a black connector(looks like it goes to the esc)...which is where the REAL pink wire was hooked to. The heavy pink wire goes directly to the main harness behind the engine. It was live with the switch on. Plugged it in directly to the BAT terminal and we have a running truck again.

To sum it up, I cooked the esc which was feeding my BAT terminal the 12v with its slightly smaller pink wire. Both pink wires have the same white terminal on the end. The truck already has an edelbrock carb on it so I'm just going to switch to an older vac advance hei and get rid of all the esc crap. Thanks again for the help.

Mitch

 

[Georgeb]

Glad you figured it out! And that you told us. I still wonder how your wrench short to ground fried it. If the negative terminal of the battery was dissconnected at the time perhaps the back feed went through that circuit to ground through the engine ground strap. Not sure how the grounds are tied together without looking at a scematic. Anyway glad its running!