Greetings all... I was taking a cruise today, ol' heaps been running great for weeks. I was just riding along about 50mph...being nice, and it just died !! No stumbles, no backfires, no noises, nothing odd... like I just turned off the key. Pulled it over, checked for obvious disconnects, cables, hoses,etc. It's getting gas, cranks over, no start. Got lights, got gas, got cranking, appears no spark to coil. Called my neighbor, who pulled his coil ( nice having a neighbor with a 66' too). But still no go.... We put the tow bar on and limped home. It's in the garage right now and I haven't looked at it yet ( after dorkin' in the blazing sun for several hours I'm pi$$ed!!). It's a 66' with a 402, Mallory Unilite, and external ballast. I'm hoping the ballast is open and that's my prob. I searched a bit, but didn't find a "no-spark 101" thread for static checks I should perform, assuming the ballast is NOT cooked. Also, can I just bypass the ballast to see if it starts ?? I would not run it for long without to avoid cooking parts...just for testing purposes. btw...the fuses all look good too, but I will doublecheck later. Any ideas why it would just die like this ??? This is a first for me... Appreciate any comments...
https://home.comcast.net/~dkloss

Time to get out the volt meter and start checking voltages under load.

Stickman,

Have you pulled the cap to see if the dist is spinning?

If you have an ohm meter, you can test the ballast - should be about 1 ohm.

The Unilite uses an LED, a shutter and optical sensor instead of points or magnetic pickup. Could be that the LED or sensor has fried. Here's a link to Mallory's web site that explains how to test it:

http://www.malloryracing.com/AskTechResults.aspx?BrandID=6&ID=108410

HomerJ

Thanks for the replies... I'll check under the cap, but I think my prob is before the dist. I'm not even getting a spark to the coil. I was curious if anyone else had a ballast resistor open, and if this is maybe the issue. I think I can bypass for troubleshooting... I thought there was couple threads that went thru a series of voltage checks, working from the IGN block back...but I couldn't locate. I have some issues to address today, but I'll be checking out tonight or tomorrow....thanks

Ok... Ballast resistor..2 ohms, so he's not open. Key in ACC position, have 12v at fuseblock ACC. Key in ON position, 12v at IGN on fuseblock. Still no 12v to ballast resistor...but all other lights,etc work, and it cranks. Continuity check on cables all appear sound. Would a faulty ignition switch still crank the starter, but not energize the coil ??? I'll probably pull that next and check. As stated earlier, when it died, it was like I just turned the key off... it was running perfectly up until that point... ( and I was just telling the wife I haven't had to drop any money into the ol' heap lately...jinxed !!)

IF you have 12 volts (checking while under load and while cranking) at the IGN terminal on the fuse block and IF that's where the other end of the wire going TO the ballast is connected, then THAT wire has power one one and not on it's other end.
That doesn't make sense to me :confused:

Dean...thanks for the reply. Agreed, something is odd here. From some previous posts I've been reading, it appears that when you turn to START, it applies 12v to the coil, then once you release the key to RUN some magic happens that maintains voltage to the coil ??? I think my START position in the ignition switch is not initially passing that 12v to the coil (or ballast in my case) to get the spark going. I still have to verify that assumption. I'm just doing some visual checks now under the dash. It's a birds nest from previous owner. I've already ripped the seats out so I can lay flat for some serious under dash work. The radio , autometer gauges, ashtray, heater controls all have to come out to really get a clear shot at the ignition switch. Now, can is open...worms everywhere...I'm gonna clean up / redo all this crap hanging under the dash. I ordered a new ignition switch since mine was sloppy anyway, and my gut says is the prob... would it be wise to also replace the key cylinder ??? ( although I really wish to keep the original keyset ... )

OK...I placed a DVM before the ballast. In START position, I had 12v... (wasn't there earlier), so I tried to start the car. Started right up...and 20 seconds later, DVM went to 0v, car stalls. Now 0v at ballast. WTF. Now I'll need to take a second DVM, and place at IGN on fuseblock. Assuming I'll have 0v on both meters, would it be safe to assume the Ignition switch is my problem ??? There's not much technology left inbetween the key and the ballast at this point. ARRGH!!!

Now I'm REALLY confused. Key in START position, 12v at the IGN on fuseblock, 0v at the ballast. I pulled the coil wire (brn) from the ballast, and removed the ballast completely to eliminate any coil draw...still 0v, and still 12v at IGN. Now it's continuity time... I'll need to trace where these wires go. ( I have wiring diagram, but I think it's beyond factory correct now ) Question... does the IGN from the fuseblock, go back up to the ignition switch, and then go from switch, back out to ballast / coil ??? I'll have to unbundle the harnesses to trace, but I thought someone may be able to confirm... thanks in advance...

That IGN terminal on the fuse block is fused.
Might check for a bad connection from fuse clips to fuse ends.

The bypass circuit that sends 12 volts to the coil's + terminal during "start" comes from the "R" terminal on the starter solenoid (yellow wire) So you should have two wires on that + termnial, one from the ballast resister and one from the "R" terminal on the starter.

Dean... I replaced the older contact flavor voltage regulator, with a Wells solid state unit about a month ago. I had excessive voltage to the battery and the lights were pulsing. The Wells made a big difference with both issues,,,,but, could an intermittent VR have anything to do with lack of voltage at the coil ??? I wouldn't think so since the ignition wire appears to be directly connected to the horn relay buss, but I'm just going over things I've done recently that may have caused this current situation...thanks

Dean... I replaced the older contact flavor voltage regulator, with a Wells solid state unit about a month ago. I had excessive voltage to the battery and the lights were pulsing. The Wells made a big difference with both issues,,,,but, could an intermittent VR have anything to do with lack of voltage at the coil ??? No


I wouldn't think so since the ignition wire appears to be directly connected to the horn relay buss, but I'm just going over things I've done recently that may have caused this current situation...thanks

We really need to know exactly how the ignition system is wired to give a clear answer. One side of ballast goes to dist,, where does the other side go to, firewall bulkhead, or ign terminal at fuse box or ??? It can't be wired to the horn relay buss bar unless there was another relay. If possible post pics.

Greg... think I located a "situation". Appears to be a rig at the bulkhead. Take a look at my diagram, and the bulkhead picture. I didn't start taking voltages at this point yet, but I was curious if you would know what that "orange braid" wire is in the bundle. I'm going to refer to my wiring diagram in the meantime. Can I just pop the harness from the bulkhead to get a better look inside ?? I'll assume batt ground should be disconnected before dorking with these harnesses. I don't think this is factory GM wiring I'm looking at here

This burned wire looks like it might be your problem to me.
The IGN primay wire is soldered to a portion of the old resistive wire ?

>>This burned wire looks like it might be your problem to me.
The IGN primay wire is soldered to a portion of the old resistive wire ?<<

Dean...is that what that braided wire is ....the remains of the original resistive loom wire ??? Should I try to trace that out to see where that goes ??? And can I just pop off the bulkhead harness ??? I'm reluctant to go tugging on 40 year old plastic...don't want to break the harness. I'd like to make sure something isn't cooked inside the bulkhead between the harness and fuseblock since I do have 12v at fuseblock IGN...but not on firewall side... Thanks for your assistance

>>This burned wire looks like it might be your problem to me.
The IGN primay wire is soldered to a portion of the old resistive wire ?<<

Dean...is that what that braided wire is ....the remains of the original resistive loom wire ??? Should I try to trace that out to see where that goes ??? And can I just pop off the bulkhead harness ??? I'm reluctant to go tugging on 40 year old plastic...don't want to break the harness. I'd like to make sure something isn't cooked inside the bulkhead between the harness and fuseblock since I do have 12v at fuseblock IGN...but not on firewall side... Thanks for your assistance
I would bet $$$ that your problem is right there. Looks like the wire overheated and melted the insulation. Yes, that is the original resistance wire. It is only a resistance wire on the engine compartment side, the dash side is regular wire. You basicly have 2 choices, either pull the bulkhead, replace the wire and most likely the connectors, and 67's use a twinlock connector, or just bypass the bulkhead connector. If you decide to bypass it, I would get power off the IGN switch (look for a 12g pink).

Here are some links on twinlock connectors
http://www.chevelles.com/forums/showthread.php?t=148099
http://www.chevelles.com/forums/showthread.php?t=54558
http://www.camaros.net/forums/showthread.php?t=65254

Gents... turns out the twinlock connectors were the prob. I carefully pulled them out of the harness, cleaned them up, resoldered/crimped connections, replaced the old ignition/coil wires, and she started right up. I also replaced the ignition switch ( since I already bought it ), so I had to pull the radio and heater controls,,, so while I was at it, pulled that nasty dry rotted speaker, ratty glove box, then ripping out the old wiring, speedo cable that's making noise, fix that flakey knee-knocker, get that AM radio workin', replace those dead bulbs... Hmm...maybe I'll replace those old dry rotted body mounts too while I'm at it ;-) At least she's running again...thanks for the suggestions

:) Glad you found the problem