electronic ignition module woes
05-24-2012, 07:03 AM
#1
New Member
Thread Starter
Join Date: Mar 2012
Location: Ft. Wayne, IN
Posts: 5
Likes: 0
Received 0 Likes
on
0 Posts
electronic ignition module woes
I have a 1974 duster and the problem I am having is with my ECU. The one on my car is the original and is a 5 pin, my dilema is that all the ones I am finding are 4 pin. does this make a difference or can I just replace mine with a 4 pin module and not have any issues?
Thank you gentlemen for your aid.
Thank you gentlemen for your aid.
05-24-2012, 09:37 AM
#2
Bolt in the 4 pin ECU and go, but while you're at it, check the reluctor gap in the dist. O' Reallys actually stocks brass feeler gauges. You need a .008". That is INCHES, not mm
Here's the story on 4/5 pin ECU's
The older design 5 pin ECU's require the old style 4 terminal ballast
The newer design 4 pin ECU's WILL REPLACE the 5 pin modules directly, and only NEED a 2 terminal resistor, but WORK with either 2 or 4 terminal resistor.
(The "other half" of the 4 terminal resistor is simply not connected)
Also, you can NOT tell some brands of replacement ECUs by just looking. Many 4 pin ECU's STILL HAVE 5 pins, it is simply that the 5th pin is not connected, so if you need to know, you must use a meter and check continuity from/ to the 5th pin
If you look at these simplified diagrams from "MyMopar" you'll see that half the resistor and one wire were eliminated in the 4 pin ECU design
from this page:
http://www.mymopar.com/index.php?pid=31
What is NOT shown in these diagrams is the brown "resistor bypass" wire for starting, which connects to the coil + side of the ballast resistor
The old 5 pin design. The left half of the resistor and the wire connected at the bottom were eliminated in the 4 pin:
and the newer 4 pin:
Here's the story on 4/5 pin ECU's
The older design 5 pin ECU's require the old style 4 terminal ballast
The newer design 4 pin ECU's WILL REPLACE the 5 pin modules directly, and only NEED a 2 terminal resistor, but WORK with either 2 or 4 terminal resistor.
(The "other half" of the 4 terminal resistor is simply not connected)
Also, you can NOT tell some brands of replacement ECUs by just looking. Many 4 pin ECU's STILL HAVE 5 pins, it is simply that the 5th pin is not connected, so if you need to know, you must use a meter and check continuity from/ to the 5th pin
If you look at these simplified diagrams from "MyMopar" you'll see that half the resistor and one wire were eliminated in the 4 pin ECU design
from this page:
http://www.mymopar.com/index.php?pid=31
What is NOT shown in these diagrams is the brown "resistor bypass" wire for starting, which connects to the coil + side of the ballast resistor
The old 5 pin design. The left half of the resistor and the wire connected at the bottom were eliminated in the 4 pin:
and the newer 4 pin:
The following users liked this post:
Scott93307 (12-18-2021)
05-24-2012, 07:18 PM
#4
Mopar Fanatic
12-19-2021, 09:19 AM
#5
9 years later and I am fighting the same issue I bought a 1972 d100 that was sold with electronic ignition because it’s a California truck and the wiring has been butchered over the years neither of these diagrams show the voltage regulator were they not used? Thanks Scott
12-22-2021, 05:31 AM
#6
I have a 1974 duster and the problem I am having is with my ECU. The one on my car is the original and is a 5 pin, my dilema is that all the ones I am finding are 4 pin. does this make a difference or can I just replace mine with a 4 pin module and not have any issues?
Thank you gentlemen for your aid.
Thank you gentlemen for your aid.
12-22-2021, 05:32 AM
#7
Bolt in the 4 pin ECU and go, but while you're at it, check the reluctor gap in the dist. O' Reallys actually stocks brass feeler gauges. You need a .008". That is INCHES, not mm
Here's the story on 4/5 pin ECU's
The older design 5 pin ECU's require the old style 4 terminal ballast
The newer design 4 pin ECU's WILL REPLACE the 5 pin modules directly, and only NEED a 2 terminal resistor, but WORK with either 2 or 4 terminal resistor.
(The "other half" of the 4 terminal resistor is simply not connected)
Also, you can NOT tell some brands of replacement ECUs by just looking. Many 4 pin ECU's STILL HAVE 5 pins, it is simply that the 5th pin is not connected, so if you need to know, you must use a meter and check continuity from/ to the 5th pin
If you look at these simplified diagrams from "MyMopar" you'll see that half the resistor and one wire were eliminated in the 4 pin ECU design
from this page:
http://www.mymopar.com/index.php?pid=31
What is NOT shown in these diagrams is the brown "resistor bypass" wire for starting, which connects to the coil + side of the ballast resistor
The old 5 pin design. The left half of the resistor and the wire connected at the bottom were eliminated in the 4 pin:
and the newer 4 pin:
Here's the story on 4/5 pin ECU's
The older design 5 pin ECU's require the old style 4 terminal ballast
The newer design 4 pin ECU's WILL REPLACE the 5 pin modules directly, and only NEED a 2 terminal resistor, but WORK with either 2 or 4 terminal resistor.
(The "other half" of the 4 terminal resistor is simply not connected)
Also, you can NOT tell some brands of replacement ECUs by just looking. Many 4 pin ECU's STILL HAVE 5 pins, it is simply that the 5th pin is not connected, so if you need to know, you must use a meter and check continuity from/ to the 5th pin
If you look at these simplified diagrams from "MyMopar" you'll see that half the resistor and one wire were eliminated in the 4 pin ECU design
from this page:
http://www.mymopar.com/index.php?pid=31
What is NOT shown in these diagrams is the brown "resistor bypass" wire for starting, which connects to the coil + side of the ballast resistor
The old 5 pin design. The left half of the resistor and the wire connected at the bottom were eliminated in the 4 pin:
and the newer 4 pin:
07-14-2022, 07:45 PM
#9
New Member
Join Date: Jul 2022
Posts: 1
Likes: 0
Received 0 Likes
on
0 Posts
Spark issues
I have a 1973 Dodge Challenger that I have been having problems with keeping spark if loses it completely and some times intermittently I’ve tried a lot of things including a wiring harness still no spark any ideas and would it be simpler to convert it to points
07-15-2022, 01:51 AM
#10
Mopar Lover
X -
Have you tried replacing the ECU, voltage regulator and ballast resistor(s)?
Assume the dist cap and rotor are new?
Points might solve the problem, but then you have "points".
Archer
Have you tried replacing the ECU, voltage regulator and ballast resistor(s)?
Assume the dist cap and rotor are new?
Points might solve the problem, but then you have "points".
Archer
07-15-2022, 09:35 AM
#12
HEAVY on cleaning those grounds. my fury would die out of nowhere, at speed sometimes. took me foreeeever to find the issue, which was the actual box itself wasnt touching bare metal. i took it off, chipped paint with a screwdriver, put it back on, and it stayed lit after that. that was a tough gremlin to chase down! 
07-15-2022, 11:56 AM
#13
Mopar Lover
HEAVY on cleaning those grounds. my fury would die out of nowhere, at speed sometimes. took me foreeeever to find the issue, which was the actual box itself wasnt touching bare metal. i took it off, chipped paint with a screwdriver, put it back on, and it stayed lit after that. that was a tough gremlin to chase down!
03-12-2023, 02:11 PM
#15
New Member
Join Date: Mar 2023
Posts: 2
Likes: 0
Received 0 Likes
on
0 Posts
thanks for been so helpful and took from your time to answer and that encourage me to post my problem too.
Last edited by seriong_hoo; 03-21-2023 at 07:13 AM.
Thread
Thread Starter
Forum
Replies
Last Post
