Need Help with a Crank but No Fire issue

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shanker

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I've got an issue with my wife's 75 Duster 360. (Dual Ballast Wiring)

Years ago (Like 2004) I put a Mopar Performance Distributor & ECU in the car and from that day on, have NEVER been able to use a 4 pin ECU otherwise the car will crank for days, but will not fire off until the key is returned to the *Run* position.

I recently purchased a HiRev7500 ecu for it, and it does the SAME thing.

If I grab ANY 5 pin ECU's (even from a junkyard car) everything is normal. With a 4 Pin ECU, it'll only fire off in *Run*.

what could be the issue? Is it by design? Is there a wiring issue?
 
shanker said:
I've got an issue with my wife's 75 Duster 360. (Dual Ballast Wiring)

Years ago (Like 2004) I put a Mopar Performance Distributor & ECU in the car and from that day on, have NEVER been able to use a 4 pin ECU otherwise the car will crank for days, but will not fire off until the key is returned to the *Run* position.

I recently purchased a HiRev7500 ecu for it, and it does the SAME thing.

If I grab ANY 5 pin ECU's (even from a junkyard car) everything is normal. With a 4 Pin ECU, it'll only fire off in *Run*.

what could be the issue? Is it by design? Is there a wiring issue?
Click to expand...


Here is a great article on the wiring for ECU's that was published in AllPar.

How to wire mid-1970s through mid-1980s ignition...
 
Sounds like ignition 2 is not powering the coil while cranking.

Easy test.. run a jumper from battery positive to coil positive and see if it fires while cranking.
 
Sounds like a dual ballast resistor issue.
 
Dana67Dart said:
Sounds like ignition 2 is not powering the coil while cranking.

Easy test.. run a jumper from battery positive to coil positive and see if it fires while cranking.
Click to expand...

kicked right off. Should I chase down a connection issue starting from the ignition switch?

The part that has me stumped though, is that any 5 pin ECU will work which is leading me to think that the ignition switch isn't the culprit.
 
shanker said:
kicked right off. Should I chase down a connection issue starting from the ignition switch
Click to expand...
Yes.
shanker said:
The part that has me stumped though, is that any 5 pin ECU will work which is leading me to think that the ignition switch isn't the culprit
Click to expand...
"Oh sweet mystory of life at last I have found you"

 
Are you using a 4 pin ballast resistor or a 2 pin ballast resistor...

The 4 pin ballast resistor needs the 5 pin ECU...

The 2 pin ballast resistor doesn't use the 5th pin and runs on 4....
 
krazykuda said:
Are you using a 4 pin ballast resistor or a 2 pin ballast resistor...

The 4 pin ballast resistor needs the 5 pin ECU...

The 2 pin ballast resistor doesn't use the 5th pin and runs on 4....
Click to expand...

I'm using the OE 4 Pin Ballast resistor.

most people agree that the 4 pin is backwards compatible though.
 
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attachment.jpg
 
shanker said:
I'm using the OE 4 Pin Ballast resistor.

most people agree that the 4 pin is backwards compatible though.
Click to expand...


You need the 5 pin ECU with a 4 pin ballast resistor...

But if you want to listen to 'most people', then your car will sit in the garage or driveway and won't start... Good luck with that....
 
LOL well no, you don't. You need a 4 pin ballast if you have a 5 pin box, but a 4 pin ballast will work with either a 4 or 5 pin ECU

You need to take a measurement and figure out WTF is going on, and don't disregard loose/ corroded/ intermittent connections.

With key "in run" engine stopped, coil + should see something around 6-10V If you have a pin probe or even a sewing needle/ pin, backprobe the power terminal on the ECU and make sure it's getting power

Then with key "in start" coil + should see "same as battery" IE if battery is 11.2, then coil should be same. In no case should coil+ be below 10.5V
 
halifaxhops said:
View attachment 1715713922View attachment 1715713923
Click to expand...
krazykuda said:
You need the 5 pin ECU with a 4 pin ballast resistor...

But if you want to listen to 'most people', then your car will sit in the garage or driveway and won't start... Good luck with that....
Click to expand...
Look at the dual Karl, one side is .5 ohm the other 1.2 I believe. The 1.2 is not used on the 4 pin at all but the .5 is and most regular ECU's Require that ohmage. yo run properly check put a FSM the spec is in there.
 
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