So Ive been having problems with my old duraspark 2 ignition box and I replaced that but it didn’t seem to fix the problem. The truck doesn’t start if the voltage is down around 12v, it cranks but no spark. So I put it on the charger a couple hours ago and came inside and was reading old posts on here about testing the ignition system and then just went out to test the negative side of the coil with a test light and low and behold when my helper went to crank it over the truck started right up like everything was fine. I took off the charger.

So then what I did was I checked the charge at the battery while the truck was running with a dvm and the voltage was 14.33 then I turned on the electric fan and it jumped up to 14.88 and spiked at 15 then held at 14.88. is that normal or is the voltage a little on the high side?
If it is high then could it be the voltage regulator or alternator? And could that have been my problem all along instead of the ignition module?

 

UPDATE:
I tried starting the truck up again, this time with the dvm on the battery and a test light on the coil negitive without being on the charger. With the key on enging off the test light was going crazy and the coil was making a buzzing noise like a very irratating bee and at the same time the voltage was droping very rapidly (12.98, 12.97, 12.96, down to 12.5 but then after cranking the engine and when the coil was behaving the voltage went up to 12.7) and tried to start it when the coil was throwing a tantrum and while the engine was cranking the test light stayed off and did not flash.

So I put the battery charger back on and did the same thing with the test light and dvm. same thing haponed again; the test light on the coil negitive went crazy with the key on engine off and when the engine was cranking the test light stayed off.

Is it a short somewere along the line? were would be a good place to start looking?

 

No, the voltage can be that high under load. 14.88 it means the alternator is putting out good amps.

 

Based on your description (in your first post), it sounds to me that possibly the battery may be getting weak and not able to maintain high enough voltage to sufficiently power the ignition module while under heavier cranking loads imposed by the starter. This could be exacerbated by an aging starter or even possibly faulty cabling to the battery somewhere. --

In my experience, a fresh battery in good health and fully charged with sufficient deliverable amperage reserves will typically read around 12.65V if not sometimes higher than that (depending on condition of the electrolyte, outside temps, and a couple other things).

Another thing to check is the battery condition of your DVM as well. Or at least cross check the meter with another one or with a known measurable reference voltage source. -- Your meter may be performing just fine after all... But I mention it because with some meters (not all) if their own battery is weak then the voltage readings you might be seeing *could* be somewhat off. -- If that were the case here... then you might actually have a truck battery that is really less than 12V (before charging) as well as showing a somewhat higher charging voltage on the meter than might actually be present. -- Just a thought.

As for the potential for a voltage regulator in your alternator possibly beginning to go south... someone else will have to chime in on that one. I'm not familiar enough with alternator VRs to know what their behavior characteristics generally are in declining stages of life.... mine always seem to just blow out suddenly and stop working altogether when they do.

As for the buzzing coil behavior and stuff as described in your second post...
You mentioned previously that you were having trouble with the old DSII box before replacing it --what sort of trouble are you referring to??

Was the previous DSII working well in the past, and if so.. then for how long??

Is this a DSII conversion from a previous TFI setup? If so, have you gone back and double-checked to make sure you wired up the new (or the previous) spark box exactly as it should be? --Also, is the new box a DSII unit with a blue connector/tab?? -- And is it exactly the same as the previous one that it replaced?

 

Alrighty so after testing conections and replacing conectors and testing the coil and the new spark box I think I found what the problem was. The ground is bad.
With a test light and with the key on the coil + was lit up and the coil - was barly lit, almost like a dimmer switch.
Only problem is is how do you replace the ground on the ignition system? Theres a Black wire going from the ignition box to the distributor, but were does it ground to? Is there a way to ground it better?

 

Alrighty so after testing conections and replacing conectors and testing the coil and the new spark box I think I found what the problem was. The ground is bad.
With a test light and with the key on the coil + was lit up and the coil - was barly lit, almost like a dimmer switch.
Only problem is is how do you replace the ground on the ignition system? Theres a Black wire going from the ignition box to the distributor, but were does it ground to? Is there a way to ground it better?

 

It bolts to the body of the dist inside the dist.

 

This is normal with a DS2 system.

Do the same test with the DVM to read voltage at both coil + and -.
Jim

 

With the key ON, wiggle the wires between the coil and the DS2 module. Also the Black ground wire from the DS2 module to the DIST grounding screw under the DIST CAP. The coil should start the buzzing thing when you find the bad connection, which would most likely be near a connection point, check the plugs first.

Having the battery changer on the battery might or might not help, try it both ways.
Jim

 

So I went to try the wire wiggle test today and there was no power to the coil and no power to the ignition box. I probed the red and white wires coming out of the box and traced them and they go inside the cab. So I’ve heard that sometimes the ignition switch goes bad so I dropped the steering column and pulled the connecter off the ignition switch and tested them with a test light and the two heavy yellow wires were the only ones getting power. According to my Chilton’s book the two yellow wires that plug into the ignition switch are; Yellow – starter relay/hazard and stop lights, and Grey/Yellow – heater and dir B/U (in the fuse block I think).

How do you test to see if an ignition switch is bad? If that even is the problem, im getting lost in all this ignition electrical stuff. The problem vehicle is an 84 with a 76 302 and Duraspark II. Even with a wiring diagram in front of me with a voltmeter and test light this wiring stuff is burning me out and it feels like im going in circles.

 

Yep.. that can happen. .... i'm sure most folks reading this can relate.
-- and so we usually have two choices really,

1) hang in there; dig-in ; slow-down... and carefully follow all tips & possibilities as presented while being meticulous in reporting back each step taken (you're doing fine so far).

2) get the vehicle to a qualified shop or auto-electric specialist. ~ be prepared to open up the wallet even further.

FWIW: There's no shame is paying someone else (who's qualified) to solve our problems. Sometimes it's a much quicker way to get back on the road. And sometimes it's imperative to get our main means of transport up & going ASAP!

But by doing-it-yourself (with other folks here acting as your battle-comrades) we gain the priceless opportunity to sharpen our own learning skills while helping us (and others) to achieve a deeper understanding of the great iron beasts we seem to so love.

 

Haha I think I found what the problem was - the ignition switch. Power is going into it but no power is comming out BUT it still cranks... dosent make scence but then again electical components dont make scence... to me anyway.
I ran a jump wire from the battery positive and hooked it into the red wire on the box and the coil had power with the key on. So then I went inside and turned the key and she fired right up. Does that sound like the ignition switch? Thats the only thing that hasent been replaced yet as far as the ignition goes. Its the stock switch back from 84. Scence the parts houses are closed by now Im going to run down to the parts house tomorrow and get the switch and see if that is the culprit.

 

Yes, perhaps the key-switch could be the problem. But as far as I can tell... that's still just a "maybe".

You said "power is going into the switch...but no power is coming out.."

The question is: Where are you actually measuring for voltage at? Are you looking for voltage at a test-point located right at key-switch itself? --or did you test for voltage further out in the wiring harness -- like somewhere closer to ignition module (i.e. at the red & white wires in the connector directly feeding into the box)? -- There's a big difference between these two test-points.

**Be Aware** also don't forget that you'll need to insure you have a *resistor* element of some sort somewhere in the power-feed going to the coil for normal running conditions. Otherwise you run the risk (depending on how things are wired) of putting too much electrical stress (too much current) on either the coil or the ignition module or both.

 

The ignition switch is not a plain switch like you would think. It has multiple contacts inside it, that take the power from the yellow wires and distribute it to different things in the truck. When you turn the key to off, they do not want these different components to be tied to each other as they would be if you had one plain switch with one contact in it. When you turn the factory switch to off, it takes the yellow power wire off all the different parts of the truck, and these different parts are not connected to each other. That's why there is so many wires, and why one part of the switch could be bad, while the other part works.

I hope that made sense, it's hard to explain it.

 

Alrighty Im laughing at this point because its just getting amusing now with the wiring stuff. I went down and grabbed a new ignition switch and installed it and still no power at the coil or ignition module. So laughing now I crawled underneath the dash and unhooked the gob of wires plugged into the ECM, ECC, engine control box deal, and tested the wires with a test light and found one single hot wire and ran a jump wire to the red wire that goes to the ignition module and it fired right up, however I had to pull the jump wire off the get it to turn off even with the key off.
Sounds like I have to hot wire my truck now to start it up haha.

I do have one concern with running the jump wire from the hot wire to the red wire in the engine control module under the dash - when it was running I checked the voltage at the ignition control module, under the hood, and the voltage was 15.6 and up spiking at 16.2 volts while the voltage at the battery was 14.08 volts. Wouldnt it be using the same resistor wires as before but just bypassing the ecm under the dash?

Im thinking that if I put in a ballast resistor that I could run a wire from the positive battery to a switch in the cab and then out to a ballast resistor and then from the ballast resistor to the red wire at the box. Then just flip the switch to on, turn the key and up and running. and then to turn it off just flip the switch to off with the key off....sound like a good idea? Id need a resistor to get the 12v down to 9v so it would be safe for the spark box and coil yes?