This is an old favorite of mine. Still good info.
4 pin ECU doesn't work. Old 5 pin does.
- Thread starter moparmandan
- Start date
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TrailBeast
AKA Mopars4us on Youtube
BillGrissom
Well-Known Member
Depends on the year and perhaps engine, which the OP didn't bother to mention. For anyone that needs to rewire anyway, I suggest dropping the Mopar ECU and ballast and changing to a GM 8-pin HEI module & coil (85-95 V-8 trucks). Simpler wiring, hotter spark, and more reliable. TrailBeast here sells as a kit for those who fear junkyards. While in there, smart to add a relay off BATT+ so you don't rely on the bulkhead connector resistance, and insure you ground the module well - not a rusty sheet-metal screw, applies to Mopar ECU also.
LOL, right?Key word = "should"
67Dart273
Well-Known Member
Well the 4 pin should work. If it doesn't either the ECU is bad, you are not grounding it, maybe a bad harness pin connector. The crossed wires on the distributor don't matter so far as "getting a spark." If the pickup wires are crossed, this moves the spark event in relation to the rotor, IE "rotor phasing."
It also might be that due to the Chineseoizationized aftermarket, the "new" 4 pin need a bit more trigger power. And it might be that the distributor/ connector/ magnet/ gap is such that it is right on the border line.
If you can, scare up a different distributor
If you have a tach, try disconnecting that. Make sure there is NOT a radio supression cap connected to coil NEG. It goes to the pos. terminal.
Other than that, "I got nuttin"
It also might be that due to the Chineseoizationized aftermarket, the "new" 4 pin need a bit more trigger power. And it might be that the distributor/ connector/ magnet/ gap is such that it is right on the border line.
If you can, scare up a different distributor
If you have a tach, try disconnecting that. Make sure there is NOT a radio supression cap connected to coil NEG. It goes to the pos. terminal.
Other than that, "I got nuttin"
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Since you didn't bother to read my question and everyone else seems to have figured it out, I'll help you. I'll go slow, I know weed is free in Cali. The question is about MOPAR electronic ignition.
This is an A body forum. Last A bodies (US) were made in 1976, right? Not talking trucks, F bodies or GM vehicles. Mopar electronic ignition was fully implemented in 1973, right? And we're not rewiring anything, as I stated in my first post, factory electronic ignition. No lean burn or funky emissions ****. Coil, ecu, ballast, distributor. Easy.
You are correct, the ECU does need a good ground.
All good-natured ribbing aside, what I was really hoping for is someone that had this experience, would say "yeah that happened to me" try this!
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Thanks, Del. I really think it's in the connector. Have tried 2 distributors.
No ****? Amazing. Thanks!
Hope it works for you.
Only thing working right now is a five pin! Lol
I've had them go out on Mopars, and Fords. Good thing about them, is before they go completely out, they get hot and quit, then cool off and work. I've nursed more than one home this way Never had one go bad on a GM, but from what I've been told, when they go, they're done.
Just following up. Were you able to find the module and get going?
I have been there/ done that with the Mopar 4 pin ecu’s not working on the 5 pin harness. Ive also had lots of 4 pins work with a 5 pin harness and dual ballast. I’ve also wired in a single ballast to a five pin box and the box overheated and killed the motor. Let it cool off and it would run till it overheated again. Then again some worked. Kim
Sorry Red, was on vacation and missed this. Just got the NOS 5 pin I'm going to try next. I'm right in the middle of a new harness install so it might be a couple days before I do.
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Thanks Kim. Even though I'm a Navy trained computer/electronics guy (DS), I still think there's voo-doo involved with this ****, haha.
jos51700
Green Bearing thread connoisseur
If it doesn't work after this, that could compound things!
Have you tried grounding directly to battery?? I had one that had a clean bolted ground to inner fender. Wouldn't run. Lifted the ecu up and it started running, while sparking and thus grounding to firewall. The fender wasn't grounded.
"If it doesn't work after this, that could compound things!"
Shush.
Sure have. Good clean grounds all around and a separate wire run to the neg terminal.
Like I have said, I'm rewiring the car anyway. This has been fun, but to much longer and I'm gonna gut the ignition wiring and start from scratch. I have a new ECU connector and harness ready to go. Now if that doesn't work..................
Cuda Al
Well-Known Member
At this point I'd be starting over trying to eliminate the variables.
I'd start with a raw (new) ignition harness.
P3690152AB MOPAR ELECTRONIC IGNITION HARNESS WITH TERMINALS ENDS AND HEAT SHRINK | eBay
Connect Light Blue directly to 12v
Connect Black/Yellow directly to the Coil (-)
Connect Green to ballast (if testing 5 pin modules)
Grind paint from module mounting screw hole, use bolt and tie directly to ground with wire.
Everything else should stay as it was (coil + to ballast)
Test
Alan
I'd start with a raw (new) ignition harness.
P3690152AB MOPAR ELECTRONIC IGNITION HARNESS WITH TERMINALS ENDS AND HEAT SHRINK | eBay
Connect Light Blue directly to 12v
Connect Black/Yellow directly to the Coil (-)
Connect Green to ballast (if testing 5 pin modules)
Grind paint from module mounting screw hole, use bolt and tie directly to ground with wire.
Everything else should stay as it was (coil + to ballast)
Test
Alan
Great minds think alike. Already in work.
Like I said in post #43, I'm giving one last NOS 5 pin a go.
Then starting over.
LOL. Agreed. It's a good way to learn!
Well I did learn more about Mopar electronic ignition. Mostly what I learned is the modern 4 pin ecu's like a good working, charging/electrical system pumping out 12.5 to 13.5 vdc. The old 5 piners maybe can survive with much less voltage (I was using just a well charged battery during testing). But the Chinese specials ain't happening. The re-wire of the car interrupted my fun with ecu's game. As soon as I wired in the alternator and voltage regulator, starter relay etc. all the issues disappeared. Tried a couple 4 pinners and car likes them now. Lesson learned.
Props to @67Dart273. As usual I think he was on the right track:
"It also might be that due to the Chineseoizationized aftermarket, the "new" 4 pin need a bit more trigger power."
Props to @67Dart273. As usual I think he was on the right track:
"It also might be that due to the Chineseoizationized aftermarket, the "new" 4 pin need a bit more trigger power."
jos51700
Green Bearing thread connoisseur
Never would've guessed it!
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