I know this has been discussed a 100 times but need help with not getting spark out of coil. 71 Roadrunner, Mopar Electronic ignition conversion kit with 72 B-body wiring (5 wire ecu plug), Pertronics Flame thrower coil, single ballast resister. After several attempts of starting/testing battery is low but here are the test results. Battery 12.2V, both coil terminals 11.3V, ecu orange box 11.3V. Resistance between +/- coil 1.3ohms but drops to 1.1/1.2 ohm. Secondary resistance is 1009ohm. Test the same from either +or-. Distributor test 268ohms at wires coming from dist and from ecu. The ECU has a good ground tested from pin 5. The resister test fine 1.4ohm I think. I don't have any spar parts to swap to try things. the car ran fine when parked last fall. The ballast also had the 11.3V at both terminals. I believe all my wiring is good. Any guesses ? is the coil bad ? seems to test fine. I'm baffled.

Post all you want there ain't no limits & that is our purpose is to solve problems & further this hobby & keep the furd/chebby boys where they belong. clip a 12V test light to ground & touch the tip to the coil negative primary terminal and have a helper crank it with the key & see if it blinks (stole that one from Rocky). pull the yellow with tracer wire off of the 'ign' terminal on the starter relay to disable the starter. remove all (might just be one) small wires from the coil neg primary terminal and clip a jumper wire with alligator clips on each end to that coil threaded stud terminal and drag the other end across the intake surface with you already having pulled large secondary wire out of dist & hold it 1/4" from intake (ground). see if it sparks in "run" and with a helper holding the key to "start". remove that jumper & put the neg pri coil wire(s) back on & seperate the dist pickup zigzag connector & drag the male tip of the body half across the intake metal surface (to make/break ground) & same thing see if the main coil wire held 1/4" from ground produces sparks in run and with him holding the key to crank. holler back

The first thing jumping out at me is you say you have a 5 pin ECU but only a single ballast ? The 5 pin needs the extra circuit of the 5 ohm side from a dual ballast hooked to key on voltage. If its 5 pin and you have a single ballast do you have anything hooked up to the 5th pin which you need to use on a 5 pin ECU ? Ron

I'm gonna go out on a limb & guess that the orange box died from sitting! How that happens I do not know but it did to me (not an orange one tho)

Or maybe the box has lost it's ground at the mounting bolts. I'd try rotating the mounting bolts back and forth some. Happened to me a couple of days ago. Car hadn't been started in a while.

Ron, yes the harness is an original 5 pin but the new orange box is only a 4 pin, that's why I went with the single resister. I do have a dual if it needs to be changed. Haven't lost ground at the box or anywhere else, was my first thought and I checked all those. Rapid
robert, I'm gonna try your testing method in the next day or two. I also have a friend loaning me spare parts so I can eliminate things that way.
this is a couple year old resto with under 100 miles on car. Everything is new, that's what's really frustrating. I've worked on these cars for over 35 years, everything tested good. Hmm

Pushbutton, the box I had was sat on the shelf (& was good when I pulled it) & it died there (& was never jostled or nothing) but was dead as a doornail when reinstalled months later. Tak you have checked continuities but the ECU requires special electronic testing to see if the transistor is turning on and off like it is supposed to in order to open/close the coil primary. Do some spark testing and have your buddy bring you a box to toss in & even an aftermarket (non OE Mopar) parts house 5 pin ECU will work (has a dummy (no continuity to case) pin at the green/red wire terminal

Oh then thats ok as I thought by how I read it you had a 5 pin box. Did you try the simple scratch test ? Thats where you unhook the dist connector and then with the key on take the male terminal of the dist wire harness connector but use the wire harness male terminal not the dist terminal and scratch or touch it to ground and if the box and all is good it should spark when you touch the male terminal to ground. If it sparks it tells you all is good other then the dist pick-up. Ron

The system can go from a five to a 4 with no problems but you can't take a 4 pin system and retrofit/install a 5 pin unit.

You can if the 5 pinner is an aftermarket (parts house) unit. if it is an OE Mopar 5 pin box then agreed it does require the 4 terminal (dual) ballast setup

Agreed that is why I said that the 4 can replace the 5 but the 5 can't replace a 4 in a 4 pin oem app. I can't put my fingers on the bulletin right now but have over the years done it as the 4 pin only requires 1 side of the resister.

Orange box failure. Thanks guys for all the help. Swapped the ecu with a friends box and I have spark. I can't believe how fast and with so low of use the box failed. Any alternative boxes you all recommend ? How about an oem if I can get one ?

Nacho our South American electronics guru had a write up & said the common failure on em is (iirc) the main transistor, the one you see on top. You might search here & see if you can find the info & it ain't difficult to replace. You would have to dig the goo out of the back & replace it (ain't this a fun hobby). Standard Motor Products used to make a good replacement ECU but they are made in China now & they are reasonable. I'd get two, one for the glove box & call it good & move on. Actually I'd suggest the HEI conversion ONLY with an OE black 4 terminal module listed for '75 chebby 350 SB (its easy to wire up & lets you use a full 12V coil (E coil) if desired. it is a killer setup & tons of em in the yards (dont forget the radio shack heat sink paste) but to keep it simple I'd just get a parts house replacement box