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HEI converted ignition - Ignition module hot wire from harness only has 10 volts according to multi meter


MadMax_636

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Today I was thinking about rewiring my ignition system just to clean stuff up. So I checked my battery voltage (12.98v) and then I turned my ignition ON and checked the red/hot wire going to the HEI module, it was only reading 10v I even unplugged it and tested the same wire directly to the battery ground and got the same results.

I then started the engine and let it sit on high idle to warm up.
Battery voltage now is at 14.2-14.4v

The red/hot wire stayed the same.

I'm wanting to rewire my ignition HOT and ground right off the battery. I want to use a switched relay to just trigger it.

Could I get some information on the results of my current findings and help on rewiring it? I'm hoping to get a hotter/cleaner and more consistent spark.
 
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RonD

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Well it wouldn't start if you didn't have at least 8v on the "hot" wire

Red is just a color, not always what a wires purpose is

Do you have a 4 pin HEI?
If so the connections are like this: https://forum.ih8mud.com/attachments/duhp-jpg.1273436/

The B tab is the hot wire and its also connected to the Coil's + terminal
Key on should show Battery voltage, as tested also with key on, on the B wire and at the Coil's + terminal

Wired diagram here: https://www.allpar.com/attachments/hei-mod-conv-jpg.4496/
 
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MadMax_636

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Yup, thats what I have. I tested it and running "B" is only getting 10v
 

MadMax_636

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I shut the engine off. Turned the ignition to ON and the "B" and "C
 

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Yup, thats what I have. I tested it and running "B" is only getting 10v
10v sounds like the resistor wire. You should be using the original hot wire to the original square coil. I think it was a red/lightgreen wire.
 

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MadMax_636

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UPDATE: So here is what I did.

I ran a direct wire from the battery + to the battery + on the HEI. It instantly ran better, smoother, and picked up in RPM and idle vacuum.

I tried to shut the car off with the key. It didnt work. So I unplugged the ignition HOT wire on the HEI and it shut off. So IDK why its reverse powering the system.

I did test the voltage with the direct power lead and it was reading 13.95 vs the 14.10 from the battery directly.
 

MadMax_636

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Heres a video of the wiring. So for those who might be able to ID the colours of the wiring.

I will do a better video in the morning with morons are firing fireworks off in the middle of the night in the woods...

Plus, Ill get a better look/view of the colours or the wiring... Since I clearly didnt in this video
 

RonD

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The earlier Ford Rangers had a Ballast resistor on the firewall, can't miss it, big white ceramic rectangle
Looks like this: https://m.media-amazon.com/images/I/51-j+mhBCEL.jpg

It needs to be removed from the circuit, unplug it and connect the 2 wires together

Ignition switch(ON)--------------ballast resistor------------------coil "+"/HEI "B"

Ballast resistor SHOULD lower the voltage by 4 or 5 volts, but its not needed with newer spark modules and coils

What you want
Ignition switch(ON)------------------------------------------------coil "+"/HEI "B"
 

MadMax_636

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MadMax_636

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The earlier Ford Rangers had a Ballast resistor on the firewall, can't miss it, big white ceramic rectangle
Looks like this: https://m.media-amazon.com/images/I/51-j+mhBCEL.jpg

It needs to be removed from the circuit, unplug it and connect the 2 wires together

Ignition switch(ON)--------------ballast resistor------------------coil "+"/HEI "B"

Ballast resistor SHOULD lower the voltage by 4 or 5 volts, but its not needed with newer spark modules and coils

What you want
Ignition switch(ON)------------------------------------------------coil "+"/HEI "B"
Tomorrow Ill look at it and see what I can do in terms of cleaning/fixing the wiring up.
 

RonD

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On the 2.8l, and most other Rangers in the 1980's, Ford use a Red/light Green stripe wire from the ignition switch thru the firewall to the engine bay and then to the Coil "+" and spark module

No fuses just the red/green key on 12volt wire
 

MadMax_636

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On the 2.8l, and most other Rangers in the 1980's, Ford use a Red/light Green stripe wire from the ignition switch thru the firewall to the engine bay and then to the Coil "+" and spark module

No fuses just the red/green key on 12volt wire
what about this? From when I first did this @RobbieD sent/posted this diagram for me. It says Brown/Pink wire is ignition 12v
 

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RobbieD

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Small world. I was typing the following as you posted.

According to EVTM, on the '84's there's two wires at the ignition switch which go to the coil, Red/Green (ignition) and Brown/Pink (start). These two wires are connected together before getting to the coil, so that there's voltage in both key positions..

There's two ignition systems, one of which has a resisted ignition wire and a full voltage starter wire. Off the top of my head, I think the MCU system (resisted ignition) is for 4 cylinders, and the 2.8 should be the EEC system.

The EVTM pages are below.

I'm not sure what's going on with yours. Try measuring Red/Green at the ignition switch; if it's 12V there and much less at at the coil it sounds like it's a resisted wire. In that case you could add a wire length at the switch and to the coil to bypass the resistor.

At the (old) coil, did yours have a Red/Green wire or a White/Blue hash wire?

84 MCU (1).JPG


84 EEC (2).JPG
 

MadMax_636

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However much it goes up when I get my fat ass out.
Total Drop
How much it goes down when my fat ass gets in.
Tire Size
Dry rot and old
Small world. I was typing the following as you posted.

According to EVTM, on the '84's there's two wires at the ignition switch which go to the coil, Red/Green (ignition) and Brown/Pink (start). These two wires are connected together before getting to the coil, so that there's voltage in both key positions..

There's two ignition systems, one of which has a resisted ignition wire and a full voltage starter wire. Off the top of my head, I think the MCU system (resisted ignition) is for 4 cylinders, and the 2.8 should be the EEC system.

The EVTM pages are below.

I'm not sure what's going on with yours. Try measuring Red/Green at the ignition switch; if it's 12V there and much less at at the coil it sounds like it's a resisted wire. In that case you could add a wire length at the switch and to the coil to bypass the resistor.

At the (old) coil, did yours have a Red/Green wire or a White/Blue hash wire?

View attachment 94620

View attachment 94621

I honestly dont remember what the original wire colours were. I tired looking on the dead horse of a thread (The one that started my conversion and that included every horrible step I too haha) but I couldn't find photos of the wires. I found that diagram you had sent me but that was all I really remember of that. Since I haven't touched the system since it runs great besides the 10v spark system.
 

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