Wiring Harness Issues 69 RR

[chtampa]

1969 RoadRunner
Stock Dash Wiring Harness that I will not modify.
Ammeter has been converted to volt meter
MSD EFI
MSD Hemi 6

I am trying to finish up the wiring and I need a positive(+) connecting point for the volt meter. Logic tells me it should only have power when key is ON but not on accessory. Agree or disagree?
Should it just go to the old ammeter terminals that I am going to bolt together and wrap?
Will this give power to the volt meter at the accessory position also? If so, is that bad?
Were else could it go?

Second issue is the EFI that needs a "Switched 12 volt circuit" feed. This means no power in accessory position. I know that I could run this out to the engine harness (maybe coil lead) but I would rather keep the connection under the dash. I need a terminal somewhere under the dash that is key on only. Any ideas?

Again I will not modify the factory harness, it is a perfect survivor harness.

 

[Demonic]

The volt meter does consume a tiny bit of power, it could be an issue if you have an off season like the winter states. The ammeter is constantly hot. I would power it from the switched hot buss bar side of the fuse block. There are two inputs to most Mopar stock fuse blocks, one constant, one switched.

You may be able to find a glass fuse with a "tap" - a terminal or lead attached to one end. Like this:

https://www.ebay.com/p/Wirthco-30200-Fuse-Tap-Kits/1539763555?iid=131420438101&chn=ps

If you put it in backwards, you are now adding the load to a circuit designed for likely less. Be careful w 50 yr old harnesses, the connections age, especially the big #12 wire hot in and alt circuit. BTW, that might be cavity "P" and "J", center connector.

 

[oldbee]

+1 above. If you don’t want to (modify) the harness, you almost have to come off fuse box.

 

[chtampa]

I have 1/4" spade terminal taps that I can use on the back of the fuse block. Is there a circuit that I can tie in to that is only on for ignition on the fuse block? I remember seeing a "flow Chart" for troubleshooting, that diagrammed what circuit was hot in each position of the ignition switch, but I don't remember where.

 

[PurpleBeeper]

 

[Shorthorse]

"Second issue is the EFI that needs a "Switched 12 volt circuit" feed. This means no power in accessory position."
The "switched" side of the fuse panel (Black wire) becomes hot from Ign 1 and/or Acc so there is no place in the fuse panel to get ignition only power.
When the switch is in the Acc position, power is supplied to the fuse panel but not to the Ign 1 terminal.
You have to tap into the ignition itself (Ing 1 & Ign 2) to get ignition only power but that also depends on your MSD wiring instructions tying Ign 1 and Ign 2 together. Because, in a stock switch, when you turn the key to start, power is removed from ING 1 and Acc and is present only at Ign 2 and the ST (start) terminal.
The cheap and dirty way would be to install an fused external switch specifically for your EFI. You probably don't want to do that but think of it as a theft deterrent.
As for your volt meter, where ever you find the switched connection for your EFI, connect it there.

 

[chtampa]

"Second issue is the EFI that needs a "Switched 12 volt circuit" feed. This means no power in accessory position."
The "switched" side of the fuse panel (Black wire) becomes hot from Ign 1 and/or Acc so there is no place in the fuse panel to get ignition only power.
When the switch is in the Acc position, power is supplied to the fuse panel but not to the Ign 1 terminal.
You have to tap into the ignition itself (Ing 1 & Ign 2) to get ignition only power but that also depends on your MSD wiring instructions tying Ign 1 and Ign 2 together. Because, in a stock switch, when you turn the key to start, power is removed from ING 1 and Acc and is present only at Ign 2 and the ST (start) terminal.
The cheap and dirty way would be to install an fused external switch specifically for your EFI. You probably don't want to do that but think of it as a theft deterrent.
As for your volt meter, where ever you find the switched connection for your EFI, connect it there.

Perhaps an option is to bring the coil feed wire to the inside of the firewall and plug in the EFI there.

 

[Shorthorse]

Perhaps an option is to bring the coil feed wire to the inside of the firewall and plug in the EFI there.

That would work. The only thing I would be concerned about would the possibility of that connection having too much RF interference. I don't know squat about EFI but quite a few guys are running it so hopefully someone will chime in. Maybe start a new thread specific to the EFI power.

 

[chtampa]

I spoke with a long time Mopar guy that owns a repair shop and I am doing the under hood connection with a factory plug to the coil power terminal wire and the one under the dash will be done by pulling the female plug of the same wire from the bulkhead and making a short "T" harness that will plug back in the bulkhead and allow me to plug in the extra new wire.

 

[chtampa]

Major setback!

Found that IGN1 & IGN2 are separate circuits as far as one gives power when the engine is cranking and the other gives power at the on position. The two circuits handoff to each other while starting. So I am still hunting a switched place to tap the harness. I need a power source when the switch is on and switch is at start at the same time, but not in accessory.

 

[chtampa]

"Second issue is the EFI that needs a "Switched 12 volt circuit" feed. This means no power in accessory position."
The "switched" side of the fuse panel (Black wire) becomes hot from Ign 1 and/or Acc so there is no place in the fuse panel to get ignition only power.
When the switch is in the Acc position, power is supplied to the fuse panel but not to the Ign 1 terminal.
You have to tap into the ignition itself (Ing 1 & Ign 2) to get ignition only power but that also depends on your MSD wiring instructions tying Ign 1 and Ign 2 together. Because, in a stock switch, when you turn the key to start, power is removed from ING 1 and Acc and is present only at Ign 2 and the ST (start) terminal.
The cheap and dirty way would be to install an fused external switch specifically for your EFI. You probably don't want to do that but think of it as a theft deterrent.
As for your volt meter, where ever you find the switched connection for your EFI, connect it there.

What are the possible issues if I connect IGN1 & IGN2 together? Is it going to backfeed and cause an issue somewhere else?
Will it not matter because the coil and ballast are gone?

 

[beanhead]

What are the possible issues if I connect IGN1 & IGN2 together? Is it going to backfeed and cause an issue somewhere else?
Will it not matter because the coil and ballast are gone?

IGN1&2 are already connected together, in a way..they are on each side of the ballast resistor. When people bypass the ballast resistor(with an msd, FBO etc..) they tie them directly together with no issue.

 

[chtampa]

IGN1&2 are already connected together, in a way..they are on each side of the ballast resistor. When people bypass the ballast resistor(with an msd, FBO etc..) they tie them directly together with no issue.

That is great news, I hate wiring issues!

 

[chtampa]

Auto Instruments converted my Amp Gauge to a Volt Gauge on my 69 RR. I am supposed to bolt the old terminals that attached to the back of the cluster together to keep everything else powered. I now have a positive wire that has a label saying "12v pos" hanging off the new gauge and a negative grounded to the cluster. I don't want this to have power when key is off to eliminate battery drain. Logic tells me to attach it to the old terminals that I bolted together before I insulate them. Do you see any problems?

 

[BLK 68 R/T]

You can also use a diode to get power from ign 1 and 2 so you have a constant power supply with the key on but will still be able to retain the stock setup.

 

[chtampa]

I am going to try pulling the inside wiring plugs from the bulkhead for IGN1 & IGN2 and install a 2 inch extension in between them and the bulkhead. Then tap each of the new wires and attach both of them to the wire that requires the 12v switch power.

 

[miller]

Don't know anything about this.
But, power from ignition switch, to the starter relay. Doesn't the start/run power circuits get switched at the relay? Could be way off base...just curious.

 

[oldbee]

No, relay is dead when in ‘run’.

 

[69ChargerR/TSE]

What was the solution? I attached my EFI to the drivers side of the Ballast, until I find a better location. I also need a separate location for the EFI Ignition.
I also converted my Alt to a Volts gauge and was going to connect it to the back of the fuse box to a switched connection, since I don't have A/C and most likely won't use the heater.
I have all new harnesses that I am ready to install. I am doing to connect the alternator gauge wires together, to bypass the unused gauge.