Lebron No Start- No Spark!!!

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mopower76

mopower76

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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.

You guys walked me through the wiring nightmare with the seatbelt inter-lock on my 74 dart sport! You guys should have some amazing ideas as always!

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!!!

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The problem is, I have no documentation (diagrams) for this car. But generally, some things you can try

Is this / was this lean burn and does it use a ballast resistor?

1..The spark thing you mentioned is off the track
2...Turn key to run. Measure coil + voltage to ground
3...Move meter to coil - and measure
4..Now twist key to start and measure coil + voltage while cranking

5...With key in "run" separate distributor connector and take end from engine harness (not distributor) With a spark test gap off the coil tower, tap the exposed end of the connector to ground. One single spark should happen each time

6 Remove dist. cap, and inspect reluctor for damage, rust, and debri, and wiggle test shaft play. Connect your meter to the dist connector, and crank engine. It should generate 1V AC. AC, not DC

Ignition box MUST be grounded. "Work" all connectors, on ECU, distributor, ballast, in/ out several times to scrub terminals and to "feel" for tightness. Examine them visually for corrosion, etc

If all else fails, try jumpering 12V direct to coil + and see if it starts

THE COIL/ ECU POWER IS DIFFERENT between "run" and "start." It is ALSO different between "start" using the key, and you jumpering the starter relay with the key in run.

The "run" position feeds power out through the bulkhead to the (if used) ballast resistor. THIS GOES DEAD during "start."

The only power going to the ignition system during "start" is from the IGN2 bypass circuit in the key, goes out through the firewall connector, and to the coil + side of the ballast.
 
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George Jets said:
View attachment 1716043965

One wire points distributor, 12 volt coil, and a hot wire.

Vroom Vroom
Click to expand...
I get that a points dist will (in theory) make it start and run but I’d rather dig deeper and find the root of the problem.
Plus I really don’t want to buy a points dist for it. I’ve got at least 4 Big Block Dizzys and 3 good MP BB… No small block.
 
67Dart273 said:
The problem is, I have no documentation (diagrams) for this car. But generally, some things you can try

Is this / was this lean burn and does it use a ballast resistor?

1..The spark thing you mentioned is off the track
2...Turn key to run. Measure coil + voltage to ground
3...Move meter to coil - and measure
4..Now twist key to start and measure coil + voltage while cranking

5...With key in "run" separate distributor connector and take end from engine harness (not distributor) With a spark test gap off the coil tower, tap the exposed end of the connector to ground. One single spark should happen each time

6 Remove dist. cap, and inspect reluctor for damage, rust, and debri, and wiggle test shaft play. Connect your meter to the dist connector, and crank engine. It should generate 1V AC. AC, not DC

Ignition box MUST be grounded. "Work" all connectors, on ECU, distributor, ballast, in/ out several times to scrub terminals and to "feel" for tightness. Examine them visually for corrosion, etc

If all else fails, try jumpering 12V direct to coil + and see if it starts

THE COIL/ ECU POWER IS DIFFERENT between "run" and "start." It is ALSO different between "start" using the key, and you jumpering the starter relay with the key in run.

The "run" position feeds power out through the bulkhead to the (if used) ballast resistor. THIS GOES DEAD during "start."

The only power going to the ignition system during "start" is from the IGN2 bypass circuit in the key, goes out through the firewall connector, and to the coil + side of the ballast.
Click to expand...
This is really great diagnostic information!!!
Thanks for posting!! I’ll be going over all tomorrow morning.

It was a Lean Burn but was converted to MP electronic by the original owner. (Done correctly) and does retain the ballast resistor.
 
mopower76 said:
This is really great diagnostic information!!!
Thanks for posting!! I’ll be going over all tomorrow morning.

It was a Lean Burn but was converted to MP electronic by the original owner. (Done correctly) and does retain the ballast resistor.
Click to expand...
Here are some expected readings:
Meter on coil + with key in "run." : You should see somwhere between 6--10V and not 12V. The lower voltage indicates the coil is properly drawing current through the box

Meter on coil -- with key in "run": You should see a low voltage perhaps .5--1 or 2V, the lower the better. If you read full battery, or in any case way higher than 2V, the box is not grounding the coil NEG and properly causing it to conduct

Meter on coil + cranking to start USING THE KEY: Should be close to "same as battery" when cranking, IE higher than 10.5. Compare by connecting meter to battery + and crank and read meter. Battery should be above 10.5 minimum. Below 11 indicates battery is low on charge or old and getting weak, or just plain too small (cranking amps) for the application.

Once again, to try and separate a harness/ car body wiring problem from the ignition system itself, jumper battery power direct to coil + and try check spark. Do not leave this attached any longer than to test, it's hard on the coil
 
HOW DO these simple tests work and what do they show?

The "tap test" using the distributor connector shows that the box can be triggered, but it does not absolutely prove that the box is OK. The trigger circuit could still have a problem. This tends to check most of the box, wiring, coil, and power from the key switch

Measuring coil voltage shows that the box is loading down the ballast and that it's getting power and conducting current through the coil. This means the box is grounded properly, the main transistor is properly conducting, and that the coil is not open

The cranking test shows the same thing with the changed circuit caused by the contacts in the key switch.

What you cannot thoroughly check is the distributor. Just because the pickup shows continuity does not mean it's good. The distributor connector is troublesome, as there is very little power through there--just the minute power generated by the pickup itself.

There us still a certain amount of "gamble." If all the checks are good and it still won't make spark, there can still be an oddball problem with the box, or distributor. But doing these checks narrows the "gamble percentage" and eliminates wiring and power issues.
 
Oldmanmopar said:
I thought we were talking Labron James . No start no spark.
Click to expand...
Ha! Ha!
No, everyone at all of the parts stores looks it up and asks if it’s a “Lebron” or Ben after I say it’s a 1979 Chrysler Lebaron… So the name stuck!

My back up.name for it is Dirty G (Dirty Grandma!) be a of how funky it was when I picked it up.
This is yet another late model Mopar I’m (trying to) saving from the scrap yard because if I didn’t buy it that’s where it was headed.
Poor old Lebron!

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Make sure your Mopar Electronic Ignition Brain Box is grounded good.

May have corrosion under the box and its fasteners.

Can even run a jumper ground to it if you are unsure.

No ground? Absolutely will not start, no spark.

Screenshot_20230204-104840_Gallery.jpg
 
I just added an extra ground to the control box.
All readings are correct from 67Dart273 suggestions except for cranking at battery, the voltage drops to 10.7-10.3 using 2 different batteries that are both out of running vehicles and both test between 13.3-13.8 volts.
 
Intermittent shaft failure?

Take the cap of and see if the rotor turns when you crank it over
 
IT RUNS!!!

But why???

I jumped the positive from batt + to coil + and it fired instantly… I removed the jumper while running and it stayed running.
Now it is starting every time without hesitation…

What????

So what is inconsistent??

And it also has fantastic OIL PRESSURE!!!
diymirage said:
Intermittent shaft failure?

Take the cap of and see if the rotor turns when you crank it ov
Click to expand...

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mopower76 said:
The shaft turns freely while cranking and everything under the cap looks like new.
Click to expand...
My reasoning was "what changed?"
The oil pump, you said you replaced that

Ok, how does the oil pump affect the ignition system?
The same intermediate shaft drives the oil pump and the distributor

So that's why I thought you should look there


Now the question becomes "what part of the system gets bypassed when jumping from battery positive to coil positive"

Find that and you'll find your flaw
 
I rechecked everything and all seems fine except that the cranking voltage at the coil -- is only 10.3.
Otherwise it runs exceptionally well!

So far everything works except for the power windows and cruise (needs Speedo cables(?) AC needs recharged and is still R12 but it is actually trying to cool!

All of the lights and buzzers, even the trunk light and trunk release!

The windows will be a huge undertaking but so far there is 12 volts at the switches (or where it’s missing switches!)

image.jpg
 
............Hard to say.......... I would go back and visually inspect the ignition connectors....the ballast, the ECU, and the distributor pickup. Inspect visually, "work" them in/ out several times. This gives you a "feel" for how tight, and scrubs the terminals clean. As I've said before, the dist. connector is troublesome. over the years.
 
I did exactly that yesterday morning and cleaned every post associated with the harness and dielectric greased all connections.
Sanded all grounds and replaced/repaired all loose connectors.

I’ve got a great collection of factory plugs so I even added a few to make removing/servicing easier.

So hopefully somewhere in there I have elevated the issue.
 
So since everything seems good… Back in the air to once again replace the oil pan gasket!!
This time I had it out in about an hour, getting this job down!
It’s a blessing in disguise really, the oil looked pretty clean coming out but when I got the pan down there was quite a bit of sludge and carbon that had collected and didn’t drain out.

Oil wasn’t sparkling so that’s a plus in my book!

I think it’s going to live well and be pretty healthy now!
After this, onto the windows, it’s getting hot in AZ already!!!

I got all of the power door locks working too!!
 
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