79' 318 ecu is live

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DCDuster75

DCDuster75

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Hey guys and gals, having an issue with no spark. So history, It was running then died lol I changed out the coil, then ballast resistor for a known working one, swapped distributor and still no spark. When I went to ignition module, I found that with it off the body and ignition in run position it is live, all over. Even when I grounded the case its still live. I'm leaning to bad module? Is it possible the circuit is always open now and faulty? Couple of pics showing issue, also live when run a ground wire right to the case. Any help would be a blessing, thanks.

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I'm no electrical expert by any means but, I don't think that should have power anywhere on the case. The case should be grounded very well when bolted down. A separate ground wire to the chassis is a good idea. Your ECU is more than likely shorted out. I'd try a known working one, albeit a crappy one. You don't want to try it with a quality one (There are ways to tell a good quality one from a junky foreign made one on this site) because it might ruin that too, if it's a problem with the wiring harness. I think HalifaxHops on here can help you. It looks like you're working on a Dodge van.
 
niceolddart said:
I'm no electrical expert by any means but, I don't think that should have power anywhere on the case. The case should be grounded very well when bolted down. A separate ground wire to the chassis is a good idea. Your ECU is more than likely shorted out. I'd try a known working one, albeit a crappy one. You don't want to try it with a quality one (There are ways to tell a good quality one from a junky foreign made one on this site) because it might ruin that too, if it's a problem with the wiring harness. I think HalifaxHops on here can help you. It looks like you're working on a Dodge van.
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Yes, 79 dodge camper van as the duster is on hiatus for the moment, still all same workings though and this is the best place I've found for help in all things LA motors
 
I had a somewhat similar problem (no spark) with one of my '79 318 pickup trucks several years ago and the problem was the EGR timer.
 
Oh, just noticed you are in Canada. That may not have been required up there.
 
If you look at the transistor you will note that there is an insulator between it and the box.

IIRC the metal housing of the box will have 0 volts when propperly grounded.

The housing of the transistor will have power.


The reason you have voltage everywhere when not grounded is the way transistors and other electronics work.

You are seeing power back feeding (sort of)

@67Dart273
 
1...YOU MUST MUST ground the box. What you are doing is sending yourself down a false road
2....On a "real" box the transistor is connected to the NEG side of the coil, and in normal operation WILL ZAP THE HECK out out of you because there is considerable voltage on the coil NEG
 
If the box is 'live' when it is grounded, then any metal section of the car will be live also.
 
Bewy said:
If the box is 'live' when it is grounded, then any metal section of the car will be live also
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It doesn't work quite that way.

Example...

If you hook a lightbulb up to a battery, from the negitive terminal to the positive terminal you will have 12v.

If you measure from the negitive terminal to the input to the bulb you will have 12v

If you measure from the negitive terminal to the output of the bulb you will have 0V.

If you measure from the negitive terminal to the negitive terminal you would have 0v

If you measure from the negitive terminal to the output of the bulb with the output of the bulb disconnected from the negitive terminal you will have 12v
 
If you read post #1, he says even when he grounded the box, it was still live. That means whatever metal he grounded the box to [ the car body I presume ], the metal body parts will also be live.
 
None of the rest of the body is live, I've probed all kinds of things to make sure
 
That Transistor if it is real is always live. You can get shocked from them even mouted on the car. Sounds like the ECU is bad to me.
 
halifaxhops said:
That Transistor if it is real is always live. You can get shocked from them even mouted on the car. Sounds like the ECU is bad to me.
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From what I've understood, if it is grounded properly, with ignition in run position it should not be live like it is. But ill swap it out from one on my duster then can purchase new for the duster if thats case.
 
DCDuster75 said:
From what I've understood, if it is grounded properly, with ignition in run position it should not be live like it is. But ill swap it out from one on my duster then can purchase new for the duster if thats case.
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PLEASE READ CAREFULLY what WE HAVE SAID.

That TRANSISTOR (if it is a 'real' ECU) IS NOT GROUNDED to the BOX.

Explain:

ALL "real" legitimate Mopar manufactured ECU's and ALL "real" old school replacement boxes such as NAPA Echlin or Standard Motor Products / Bluestreak used a REAL WORKING transistor which is NOT grounded to the box. That assembly you see, the transistor and the piece under it is the heat sink, is INSULATED from the box by means of mica insulation and sleeves in the screws.

THAT TRANSISTOR is CONNECTED to the COIL NEGATIVE terminal, which can have several hundred volts on it when in operation and which will SHOCK THE LIVING DAYLIGHTS out of you if you touch it when running.

FAKE transistors: Many? most? some? boxes imported from you-know-where use a DIFFERENT switching transistor which is actually INSIDE THE BOX and to make people "feel normal" they ACTUALLY INSTALLED a FAKE TRANSISTOR on the outside of the box. THOSE TRANSISTORS will not act as I said, and will in fact have the same voltage as the box, which, when PROPERLY GROUNDED will be ZERO VOLTS in reference to the firewall of the car
 
WHY AM I YELLING?

Simple. OP you seem to have a problem with reading answers. I already told you in my earlier post that your "testing" is leading you down a wrong road.

DO NOT UNMOUNT the box and DO NOT attempt to operate it that way.

GROUND the box and then go about attempting to find the answer
 
Take it easy there Andy! The Box WAS MOUNTED and still same issue. I ALSO grounded it when off the firewall to probe, (not run) Fake or not? I don't know, but believe it to be original to the motor. So easy with the I don't read crap please. Some grasp things a little differently than others.
 
1....Check spark at the coil tower and do NOT use the in place coil wire. "Rig" a wire and test gap using solid wire, even if low voltage wire, "hung" away from metal

2...Remove dist. connector. With key "in run" tap the bare terminal of the end opposite the distributor to ground. Each time should make one "SNAP" spark

3...With key in "run" measure some voltages

Voltage from coil + to ground should NOT be "same as battery," but much lower, perhaps 6--10V

Voltage from coil NEG to ground should be low, perhaps 1/2--2V or so.

Remove dist. connector. Rig your meter to the distributor connector terminals, set on low AC volts. When rotating, the dist should generate about 1 volt AC

Remove dist cap, inspect cap for dirt, moisture, or tracking at cap terminals. Examine rotor for condition and for possibility of "punch through" of high voltage through the rotor

Examine shaft for wobble or wear, and condition of reluctor for strike damage, or rust and debri.

Continuity of pickup coil should be open/ infinity to dist. case, and ?? about 200 ohms across the two. This is a disputed figure and varies with coils and is NOT A SURE TEST but shows the coil is not OPEN.

Examine all ignition system connectors, the ballast, the ECU, and distritutor. Work them in/out several times to scrub the terminals and to "feel" for tightness. Examine with a light for corrosion.

THERE IS NO good way to test the box, other than if you have eliminated other possibilities, replace it. IT MUST BE GROUNDED to operate
 
DCDuster75 said:
Take it easy there Andy! The Box WAS MOUNTED and still same issue. I ALSO grounded it when off the firewall to probe, (not run) Fake or not? I don't know, but believe it to be original to the motor. So easy with the I don't read crap please. Some grasp things a little differently than others.
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No YOU listen. You were doing off base stupidly thought out so called "testing" that was leading you down the dark primrose path.

You were already informed of this fact earlier in the thread and yet you stayed with it.

THE BOX MUST BE GROUNDED. Period

Good luck, I am done with your ***
 
Just a thanks for anyone that helped, The ignition box had a dead short. Replaced it and running like a champ. After replacing the Box isn't it live anymore on the case. Cheers
 
The confusion was this sentence:
"Even when I grounded the case its still live."

Never use "it" when having used several different nouns previously. Perhaps "it" meant the transistor, which is normally hot, so OK. If "it" meant the body of the ECU case when it was grounded by wire to BATT-, then that is confusing. Either not a good ground connection, or a massive current was flowing.

Not an English teacher, rather an engineer. We try to use exact terms, then English majors fault us for being "wordy and complicated" and suggest ambiguous words like "it" to be concise. I have seen many examples where an English major rewrote something an engineer wrote, then it no longer made sense or was unclear.
 
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