Circuit diagram of Chrysler ECU
- Thread starter Bewy
- Start date
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Not sure if I understand your question correctly, but...
At one time before ECU, the ballast resister would control the voltage / current to the coil (points)
Later with electronic ignitions there were 2 power feeds to the ignition. One was the power source for the ECU, the other was the power for the coil, a dual ballast resister fed each separately. (5 wire ECU)
A bit later the ECU was designed to run off of 12v directly. So only one ballast resister was needed for the coil. (4 wire ECU)
Pretty sure this does not answer your question but hope it sheds some light
At one time before ECU, the ballast resister would control the voltage / current to the coil (points)
Later with electronic ignitions there were 2 power feeds to the ignition. One was the power source for the ECU, the other was the power for the coil, a dual ballast resister fed each separately. (5 wire ECU)
A bit later the ECU was designed to run off of 12v directly. So only one ballast resister was needed for the coil. (4 wire ECU)
Pretty sure this does not answer your question but hope it sheds some light
Demonic
Well-Known Member
KitCarlson
Well-Known Member
IMHO, External 5 Ohm resistor and internal zener diode are used for voltage regulation in 5 pin, 4 pin uses a 3 terminal regulator LM7805.
Kit,
Thanks for the reply. If the 5 ohm is used for regulation, what component is it regulating? My guess is that resistor would have a 40-100 watt rating. Why such a high rating [ & expensive to make ] if it is regulating small components inside the ECU where a 1w carbon res would do the job.
I am wondering if the 5 ohm is a current limiter for the coil, would certainly explain the high wattage rating. This is why I would like to see the cct of the box internals.
Thanks for the reply. If the 5 ohm is used for regulation, what component
I am wondering if the 5 ohm is a current limiter for the coil, would certainly explain the high wattage rating. This is why I would like to see the cct of the box internals.
KitCarlson
Well-Known Member
I was going from memory, read long ago. I'm no expert, never ran one.
Found this 5 pin schematic in search.
Whats in the orange box ?
Results will vary, different junk in box,over years and mfg. Found in web search.
Found this 5 pin schematic in search.
Whats in the orange box ?
Results will vary, different junk in box,over years and mfg. Found in web search.
Last edited:
Thanks for that.
The orange box doesn't use the 5 ohm res, so not shown in that cct. Leads me to think that it is a current limiting device for the coil, & omitted when using higher output coils/ECU boxes. Would still like to see the cct though, to be sure.
The orange box doesn't use the 5 ohm res, so not shown in that cct. Leads me to think that it is a current limiting device for the coil, & omitted when using higher output coils/ECU boxes. Would still like to see the cct though, to be sure.
Cuda Al
Well-Known Member
I had always assumed that the 5-pin units had two power inputs, 12v and a reduced one (from the ballast)
and the 4-pin only had the 12v input and either didn't need the reduced voltage or did it internally.
Alan
and the 4-pin only had the 12v input and either didn't need the reduced voltage or did it internally.
Alan
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