Lebron No Start-No Spark!!

mopower76

Well-Known Member
Joined
Feb 3, 2013
Messages
87
Reaction score
67
Hoping that I’m posting in the correct form if not admin, please remove and recommend the correct form.
Thanks!

This is a thread in the middle of a 0 oil pressure conversion…

This is a 1979 Chrysler Lebaron (Diplomat) 318/904 MP electronic Converted from electronic, spark control, and was a running and driving vehicle.

Long story short-
I lost oil pressure on maiden voyage after sitting years, changed the oil pump got it back together and it on restart it ran for a brief moment (got oil pressure!) and it shut off like I turned off the key! Then tried to restart it ran for a second died shut off and burned a fuse able link…

So now no spark.
I pulled the complete under hood harness today and separated every wire, tested and repaired every wire including the fuse-able link and and all connections, reinstalled, tested for voltage at every point, still no spark-Kind of…

When you turn the key back to lock- using a sparkplug directly to the coil, it will spark one time every time you turn the switch back to lock. WTFudge!!!!

So this should NOT be distributor related but could be ignition switch related right???

The ignition switch and distributor are about the only two things I haven’t replaced or tested.
Wires look a mess but they will be re-loomed/taped and ram properly after I get this figured out!

Any ideas are much appreciated!!!

image.jpg


52E31CC2-21FF-4AAA-BCF7-81BCB25AEE4F.jpeg


image.jpg
 

Mikes5thAve

Well-Known Member
Joined
Mar 3, 2020
Messages
1,501
Reaction score
609
Location
Canada
Did you reconnect that second plug from the ballast resistor, and try changing that?
 

69-

Well-Known Member
Joined
Dec 13, 2020
Messages
390
Reaction score
264
Location
Germany
If you only have a spark when turning from "run" to "off", I'd think there's something wrong with the ECU, Pickup [inside distributor] and/or the associated wires.

Why?
Coil gets charged when turning from "off" to "run". Then, no change of coil voltage while starting (you might try to measure the voltage at the coil [versus ground] while starting -> it should fluctuate between like 0 and 9 volts).
If there's a problem with either pickup or ECU, there's no change in voltage at the coil and hence no spark.
Then you turn from "run" to "off" and that's a change in voltage (9V to 0V) -> that change in voltage triggers the coil and you see one spark.

Why 9V and not 12V? -> that's because of the ballast resistor, to protect the coil from too much current (limits current).
 

mopower76

Well-Known Member
Joined
Feb 3, 2013
Messages
87
Reaction score
67
I wanted to thank @Justwondering for the excellent help with pictures of the factory 1979 service manual!!

All of the pictures sent turned out great and were an invaluable resource!

They are still being used as I tackle the Power Windows!!!

Thanks again!!! Much Appreciated!!!

8769D816-4A7C-4AFF-874F-950F81F873F3.jpeg
 

mopower76

Well-Known Member
Joined
Feb 3, 2013
Messages
87
Reaction score
67
Also, thanks to everyone that contributed!!! I really appreciate it!!
 

TOPTECH

New Member
Joined
Jun 21, 2023
Messages
1
Reaction score
1
Location
chicago
Exact problem on my 83 Imperial, even bigger nightmare with a carb conversion.
IT WAS THE ICM. Amazon new ICM fooled me by making spark with probing pickup inputs, so I blamed the distributor, WRONG. Took a Mopar ICM off my Tradesman, worked perfect. ICM even had the 0.5v pu coil bias voitage. Import scourge garbage
 
Back
Top