Ignition ecu box test?

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Dusten

Dusten

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Trying to start my 71 duster with a 340 after 12 years. just rebuilt the engine. Engine turns over but getting no spark. Using a light tester, there is power getting to the + & - side of the coil, but the tester does not light up on the 2 wires coming form the chrome ecu box to the disturber. Does this mean the ecu box is not good. Is there a way to test the ecu box with like a multimeter or something? We have gone over the wiring diagram a hundred times it appears that everything is hook up correctly. It is a 4 pin ecu box. Thanks for any help you can give and let me know if you need any additional info.
 
Dusten said:
Trying to start my 71 duster with a 340 after 12 years. just rebuilt the engine. Engine turns over but getting no spark. Using a light tester, there is power getting to the + & - side of the coil, but the tester does not light up on the 2 wires coming form the chrome ecu box to the disturber. Does this mean the ecu box is not good. Is there a way to test the ecu box with like a multimeter or something? We have gone over the wiring diagram a hundred times it appears that everything is hook up correctly. It is a 4 pin ecu box. Thanks for any help you can give and let me know if you need any additional info.
Click to expand...
Hello Dustin,
This is also simple.
happy Mopar :)
Arron

upload_2018-12-13_12-46-49.png

Troubleshooting an electronic ignition system is fairly simple. Once it has been determined that there is no spark, there are a few quick checks that can be performed to determine the cause. A DC volt/ohm meter can be used to check the continuity of the pick-up coil. It can be checked at the leads as they leave the distributor, or on pins 4 and 5 of the ECU connector. When measuring the resistance across the two leads of the pick-up coil you should see a 150-900 ohm reading. Always flex the wiring leading to the distributor and to the ECU while checking the resistance to be sure that there are no breaks in the wiring. You should also check for 12 volts at pin 1 of the ECU connector when the ignition is in the "on" position. It is also important that the ECU be securely bolted in place and that bolts provide a good ground to the ECU housing. The only other lead that is connected to the ECU is the "-" lead to the coil, which can be checked to insure that it is not broken.

The other important component of the electronic ignition system is the ballast resistor. It should be checked with an ohm meter and should have 1.2 ohms of resistance. Typically, a failure of the ballast resistor will result in the engine starting, but then dying as soon as the key is released from the start position. It is often handy to have a spare ballast resistor or ECU lying around to use for troubleshooting.
 
Please check all grounds including the ignition box to fender and fender to engine and engine to battery.
If apart clean and reassemble, paint, rust and not connnect at all can do this.
Make sure your grounds are battery to engine, engine to car, and if really serious do a battery to car.
Even some resistance will cause havock.

Joe
 
Dusten said:
Trying to start my 71 duster with a 340 after 12 years. just rebuilt the engine. Engine turns over but getting no spark. Using a light tester, there is power getting to the + & - side of the coil, but the tester does not light up on the 2 wires coming form the chrome ecu box to the disturber. Does this mean the ecu box is not good. Is there a way to test the ecu box with like a multimeter or something? We have gone over the wiring diagram a hundred times it appears that everything is hook up correctly. It is a 4 pin ecu box. Thanks for any help you can give and let me know if you need any additional info.
Click to expand...

First is this system something you just installed or did it run sometime?

The ECU box MUST be grounded.
Read the checks I posted in the link posted earlier. Measure coil NEG voltage with key in "run" If it's a couple of volts or LESS the coil is properly drawing current. If the coil NEG is close to battery voltage, the ECU is not drawing current
 
Don’t know how much effort $20 is to you, but you can buy a cheap one for about that & change it out & see if it is the cause. If doesn’t fix it, it never hurts to have a spare for emergencies.
 
Arron tate said:
Hello Dustin,
This is also simple.
happy Mopar :)
Arron

View attachment 1715261341
Troubleshooting an electronic ignition system is fairly simple. Once it has been determined that there is no spark, there are a few quick checks that can be performed to determine the cause. A DC volt/ohm meter can be used to check the continuity of the pick-up coil. It can be checked at the leads as they leave the distributor, or on pins 4 and 5 of the ECU connector. When measuring the resistance across the two leads of the pick-up coil you should see a 150-900 ohm reading. Always flex the wiring leading to the distributor and to the ECU while checking the resistance to be sure that there are no breaks in the wiring. You should also check for 12 volts at pin 1 of the ECU connector when the ignition is in the "on" position. It is also important that the ECU be securely bolted in place and that bolts provide a good ground to the ECU housing. The only other lead that is connected to the ECU is the "-" lead to the coil, which can be checked to insure that it is not broken.

The other important component of the electronic ignition system is the ballast resistor. It should be checked with an ohm meter and should have 1.2 ohms of resistance. Typically, a failure of the ballast resistor will result in the engine starting, but then dying as soon as the key is released from the start position. It is often handy to have a spare ballast resistor or ECU lying around to use for troubleshooting.
Click to expand...

NOTICE!!! THAT CONNECTOR IS A MIRROR IMAGE, AKA LOOKING INTO THE CONNECTOR FROM THE BOX SIDE. Notice that this is the opposite of how most of the diagrams are drawn
 
Sorry does it come from the ignition switch or the starter relay
 
Pretty good, BUT couple things:

Don't check spark with the existing coil wire especially a resistor/ supressor wire. Use a SOLID core wire with the spark tester

"No reason to remove cap." Yes there is. LOTS of these have debri/ rust/ etc caught up in the pickup / reluctor, inspect it for shaft play and reluctor strike damage. Also ALWAYS inspect the cap and rotor for carbon tracking and rotor punch through as well as "general" conditon......ESPECIALLY on a boat, LOLOL moisture in the cap!!!

I was not aware of the .2V AC "spec" on the pickup output wonder where he got that, and was not aware that a 5 pin would run with a bad seconary ballast. "I wonder" if that box is really a 4 pin box? (You can not tell by looking as many 4 pin boxes HAVE 5 physical pins)
 
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