1973 Scamp won't start in start only in run. With a Twist....

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moparmandan

moparmandan

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Have checked all the wiring I can think of and they check good. I have a new ECU and ballast resistor. Got 5.5 volts in run and 10.5 volts in start at the coil. Have jumped straight from the battery to the positive of the coil. Also the coil negative straight to ground on the battery. Still won't start in start except VERY intermittently. What the? Any ideas?
 
What do you mean "coil negative straight to ground?" The coil neg does not go to ground. It goes to the ECU which switches the coil NEG

If it runs at all I do not understand how.

Do you understand how the ballast bypass circuit works? Sound like it is OK. the ignition switch has a dedicated contact (IGN2) which goes direct to the coil + side of the ballast. This is (should be) where you are getting the 10.5 in crank

Review your wiring. Make certain the ECU is well grounded

This diagram is correct except it does not show the IGN2 bypass

Wire at far top right labeled "existing" goes to IGN1 "run" circuit

Ignition_System_4pin.jpg
 
67Dart273 said:
What do you mean "coil negative straight to ground?" The coil neg does not go to ground. It goes to the ECU which switches the coil NEG
Jumped the coil to gnd in case it was not getting it from the ECU during cranking.

If it runs at all I do not understand how.
Me neither. Cranks, let key go to run, vroom. Damndest thing Ive ever seen. Timing and carb must be good!

Do you understand how the ballast bypass circuit works? Sound like it is OK. the ignition switch has a dedicated contact (IGN2) which goes direct to the coil + side of the ballast. This is (should be) where you are getting the 10.5 in crank
Yes, I think so. I'm an electronics tech, BTW. Navy trained. This is starting to anoy me......

Review your wiring. Make certain the ECU is well grounded
Thats next. I wired it's own 12 awg gnd. Maybe the paint on the ecu?
But the ECU is out of the circuit during start, right?

This diagram is correct except it does not show the IGN2 bypass

Wire at far top right labeled "existing" goes to IGN1 "run" circuit

Thanks man. I've seen your other responses to this problem. Hopefully when this is done I'll know it as well as you!

View attachment 1715139567
Click to expand...
 
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67Dart273:
For some reason my answers to your questions are up there^^^
Also, so far ive checked for start voltage at the coil and the brown wire splice. 10.5 vdc. But still won't start until you release the switch to run. I swear I'm not making this up.
 
Geez. Two replies.......

Post a question about an electrical problem, people run. Guess I should post a necked girl or ask about frozen TV dinners.:rofl::rofl:
 
Well troubleshooting by remote control "is hard" LOL

I guess all I can suggest is to go over the wiring carefully. One thing I'd suggest is to isolate the ignition from the rest of the wiring and jumper it to run. In other words separate it from both the "run" and the "bypass" circuits, IGN1 and ING2.

They carefully check both those sources WITH A LOAD applied, IE an old headlight or anything 12V you can find that will draw maybe 5A or so. Measure voltage in "run" and "start."

Is there any other added electrical wiring/ changes?

How about former damage, IE wires crossed / melted in the harness?

It might also be that happenchance is leading you down the wrong path. An intermittent/ poor connection in either the ECU connector or the distributor pickup connector can drive a guy nuts
 
There are drawings on the web that show both IGN 1 and IGN 2. Some that show the 5 pin ECU and dual ballast resistor too if required.
And since coil ground is controlled at the ECU, the ECU must be chassis grounded, ( also not shown ). Beyond that, I read a voltage drop somewhere. IGN 1 and 2 should show closer to 12 volts. The less you put in a ballast resistor the less you get out. 5.5 is too low for it to run right, if at all.
 
moparmandan said:
Geez. Two replies.......

Post a question about an electrical problem, people run. Guess I should post a necked girl or ask about frozen TV dinners.:rofl::rofl:
Click to expand...

I may be able to speak to that...only 2 responses, but one from Del, who if anybody here knows electrical, is the best person to help you! When Del chimes in on electrical issues, it is in the right hands! Not sure of his knowledge on TV dinners, but on electrical, he is the man!!
 
67Dart273 said:
Well troubleshooting by remote control "is hard" LOL

I guess all I can suggest is to go over the wiring carefully. One thing I'd suggest is to isolate the ignition from the rest of the wiring and jumper it to run. In other words separate it from both the "run" and the "bypass" circuits, IGN1 and ING2.

They carefully check both those sources WITH A LOAD applied, IE an old headlight or anything 12V you can find that will draw maybe 5A or so. Measure voltage in "run" and "start."

Is there any other added electrical wiring/ changes?

How about former damage, IE wires crossed / melted in the harness?

It might also be that happenchance is leading you down the wrong path. An intermittent/ poor connection in either the ECU connector or the distributor pickup connector can drive a guy nuts
Click to expand...

Well troubleshooting by remote control "is hard" LOL
Indeed.
I guess all I can suggest is to go over the wiring carefully. One thing I'd suggest is to isolate the ignition from the rest of the wiring and jumper it to run. In other words separate it from both the "run" and the "bypass" circuits, IGN1 and ING2.
Now there's a good idea. I'm wondering if it's in the switch. Should I disconnect at the switch harness coming out of the column?
They carefully check both those sources WITH A LOAD applied, IE an old headlight or anything 12V you can find that will draw maybe 5A or so. Measure voltage in "run" and "start."
Gotcha. Will do.
Is there any other added electrical wiring/ changes?
Yep, pin P and J have both been bypassed and new wires run to the amp meter due to overheating. Done by PO. That would concern me (Q is next door) except for the 10.5 vdc at the coil while cranking.............
So I guess it's not the ignition switch.......
Could it be the coil? But it's starts in run????????
Am I loosing neg to coil while in start bypass??????
****...........
How about former damage, IE wires crossed / melted in the harness?
See above.
It might also be that happenchance is leading you down the wrong path. An intermittent/ poor connection in either the ECU connector or the distributor pickup connector can drive a guy nuts
Yup. And like any good tech that's getting his *** kicked I'm gonna start throwing parts at it. HaHa. One at at time of course. Already swapped in my spare distibutor. Same same. Just happen to have laying around, a new ECU, coil, ballast resister, new ecu connector and wiring harness. Will clean up the gnd's again and check all wires again. Thank's alot for the help.
 
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cosgig said:
I may be able to speak to that...only 2 responses, but one from Del, who if anybody here knows electrical, is the best person to help you! When Del chimes in on electrical issues, it is in the right hands! Not sure of his knowledge on TV dinners, but on electrical, he is the man!!
Click to expand...
If Del is 67Dart273, yes. He know's his ****.
 
RedFish said:
There are drawings on the web that show both IGN 1 and IGN 2. Some that show the 5 pin ECU and dual ballast resistor too if required.
And since coil ground is controlled at the ECU, the ECU must be chassis grounded, ( also not shown ). Beyond that, I read a voltage drop somewhere. IGN 1 and 2 should show closer to 12 volts. The less you put in a ballast resistor the less you get out. 5.5 is too low for it to run right, if at all.
Click to expand...

HaHa that's the hell of it. Run's great!
The voltages are taken at the coil and the brown wire splice. After the resistor.
Will check the ecu ground tonite. Thanks!
 
I've got the same problem When I engage the starter with the key the coil goes to 0 volts. release the key to run and 12 volts comes back. turn the key to run and bump it with the solenoid and it starts. aftermarket coil and distributor no ballast resistor . My trouble started when I moved the coil near the fender.
 
sorewrist1 said:
I've got the same problem When I engage the starter with the key the coil goes to 0 volts. release the key to run and 12 volts comes back. turn the key to run and bump it with the solenoid and it starts. aftermarket coil and distributor no ballast resistor . My trouble started when I moved the coil near the fender.
Click to expand...

That is perfectly normal .
You have got to jumper the brown and blue wires together, else the coil goes dead . This has the side effect of sending power to the starter with the key in run. To prevent that, I installed a relay in the brown wire to the coil instead of the jumper
 
I'm out of ideas without being there.
moparmandan said:
Who me? I've been nothing but respectful and grateful for the help. What are you referencing?
Click to expand...

We are good LOL. But by "remote control" I'm running out of ideas. One suggestion
...................."rig" an old tail lamp for a test light..............

"Revisit" your voltage tests at coil+, in run and in "start" with the meter AND WITH the tail light test lamp hooked up, which will load the circuit some. Your coil + "run" voltage will be lower of course, more drop through the ballast

Likely the "usual suspects" here in no order is:

The ignition switch itself
The switch connector
The bulkhead connector
The ECU connector

That is assuming that lack of power/ voltage to the circuit is the problem
 
67Dart273 said:
I'm out of ideas without being there.


We are good LOL. But by "remote control" I'm running out of ideas. One suggestion
...................."rig" an old tail lamp for a test light..............

"Revisit" your voltage tests at coil+, in run and in "start" with the meter AND WITH the tail light test lamp hooked up, which will load the circuit some. Your coil + "run" voltage will be lower of course, more drop through the ballast

Likely the "usual suspects" here in no order is:

The ignition switch itself
The switch connector
The bulkhead connector
The ECU connector

That is assuming that lack of power/ voltage to the circuit is the problem
Click to expand...

I'm out of ideas without being there.

Come on down the weather is awesome!

We are good LOL.

Good. I didn't think I had said anything to offend you, haha.

But by "remote control" I'm running out of ideas. One suggestion
...................."rig" an old tail lamp for a test light..............

"Revisit" your voltage tests at coil+, in run and in "start" with the meter AND WITH the tail light test lamp hooked up, which will load the circuit some. Your coil + "run" voltage will be lower of course, more drop through the ballast

So that would be checking for an iffy conection, with a little more load trying to get the voltage to drop out completely?

Likely the "usual suspects" here in no order is:

The ignition switch itself
The switch connector
The bulkhead connector
The ECU connector

That is assuming that lack of power/ voltage to the circuit is the problem

I'll figure it out this weekend and report back. Thanks alot for your help. Never say quit!
 
sorewrist1 said:
I've got the same problem When I engage the starter with the key the coil goes to 0 volts. release the key to run and 12 volts comes back. turn the key to run and bump it with the solenoid and it starts. aftermarket coil and distributor no ballast resistor . My trouble started when I moved the coil near the fender.
Click to expand...
I wish mine would drop out to 0 volts then I'd have something I could troubleshoot! Your loosing yours on the start circuit, acc2. Little different but the same suspects
The ignition switch itself
The switch connector
The bulkhead connector
The ECU connector
 
AJ/FormS said:
That is perfectly normal .
You have got to jumper the brown and blue wires together, else the coil goes dead . This has the side effect of sending power to the starter with the key in run. To prevent that, I installed a relay in the brown wire to the coil instead of the jumper
Click to expand...
OK Connect the brown and blue wires together Before the brown and blue connect put a relay on the brown . If thats correct so far what powers the relay? The blue? The instrument lights are involved someway in this mess and don't work. Could they also make a miraculous recovery? That could be a separate issue. Thanks for the reply. I did the ign1 ign2 thing 2 years ago and thought every thing was fine. moving the coil and taping the wire bundles may have upset something .untaping I will go. Thanks Jim
 
sorewrist1 said:
OK Connect the brown and blue wires together Before the brown and blue connect put a relay on the brown . If thats correct so far what powers the relay? The blue? The instrument lights are involved someway in this mess and don't work. Could they also make a miraculous recovery? That could be a separate issue. Thanks for the reply. I did the ign1 ign2 thing 2 years ago and thought every thing was fine. moving the coil and taping the wire bundles may have upset something .untaping I will go. Thanks Jim
Click to expand...
oops didn't mean to hijack the thread. Thought I was starting a new one
 
No worries. It's all related. Maybe I will learn something. But while we are BS'n what do you mean by doing the ign1 and ign2 thing?
 
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