Wiring question

[Knuck]

Can anyone tell me where the Red with Blue stripe wire from the start position on the ignition switch enters the engine compartment? I am not seeing said wire on the passenger fender well. It goes from the ignition switch to the "S" terminal on the starter solenoid/relay. I am older so rummaging around under the dash to trace it is painful for me.

Sent from my SM-S901U using Tapatalk

 

[Oldtimer]

What year Bronco?

 

[Knuck]

Sorry,meant to include that. 76 w/manual trans.

Sent from my SM-S901U using Tapatalk

 

[Knuck]

I can see it coming off the switch, but lose track of it. Wiring diagram says it goes to c-222.

Sent from my SM-S901U using Tapatalk

 

[Oldtimer]

I would expect it to go thru passenger side grommet.
There may be a second RD/BU wire to the Duraspark ignition module.
If yours is mounted on driver side of engine compartment, you may find wire coming thru one of the other holes.

 

[Oldtimer]

C-222 may be the four wire connector that contains wires for neutral saftey switch and back up lights. I think it is near the "engine section" feed thru.

On the manual transmission it has a loop to complete the circuit.

See this thread: https://classicbroncos.com/forums/threads/electrical-question.230751/

 

[Broncobowsher]

That's what I remember. The reverse light switch on the steering column (engine side) has that 4-pin plug. It allows the same basic harness to be used with both manual and automatic transmissions. With the manual, the start signal gets the jumper and the reverse lights go to the switch on the column. But if an automatic is optioned, that 4-pin plug is now hooked up to the transmission which does the reverse light and the loop is interrupted with the neutral safety switch.

The quick thing to do is look for the reverse light switch on the column and follow those wires. The switch is pretty basic, when you shift into reverse, that arm makes contact with the switch. Right where the rods connect to the column.

 

[Knuck]

I converted mine to a floor shift years ago, but did nothing with the wiring harness when I did so. I finally found the red/blue stripe wire. It was in plain sight, but the blue stripe has faded to black (queue up the Rolling Stones). That said, something is amiss somewhere, as the wire is not getting power when the key is turned to the start position.

Sent from my SM-S901U using Tapatalk

 

[Knuck]

View attachment 925025

I would expect it to go thru passenger side grommet.
There may be a second RD/BU wire to the Duraspark ignition module.
If yours is mounted on driver side of engine compartment, you may find wire coming thru one of the other holes.

View attachment 925026

Wondering if the dura spark box not being present would cause my no power to the red/blue stripe wire when the switch is in the start position. I have power in the run position, but not in start. Engine is now efi, with a Microsquirt ECU. Runs great it I use a jump switch from battery to s terminal on the starter relay.

Sent from my SM-S901U using Tapatalk

 

[DirtDonk]

Check the 4-wire plug that Oldtimer listed, coming through the firewall behind the engine.
Is this a manuel transmission bronco from the factory? Or did it have an automatic originally, and you converted it?
That jumper wire for use with manual transmissions may have become dislodged, or failed. That’s one of the more common reasons you don’t have power on the red with blue wire on ‘73 through ‘77 Broncos.
Now, if it had an automatic and you changed it out, you’ll need to create your own jumper to take the place of the old neutral safety switch.

At least check for power there at the connector if no power at the connector, then the problem is probably in the ignition switch itself, or the wire between that connector and the ignition switch. If there’s power, then you have to make sure the jumper is good.

 

[Broncobowsher]

Wondering if the dura spark box not being present would cause my no power to the red/blue stripe wire when the switch is in the start position. I have power in the run position, but not in start. Engine is now efi, with a Microsquirt ECU. Runs great it I use a jump switch from battery to s terminal on the starter relay.

Sent from my SM-S901U using Tapatalk

That's normal. The ignition switch may or may not drop ignition power while in start. In the original configuration it doesn't matter, the "I" wire off the starter solenoid takes care of that.
You will get people why say they never had an issue and always have run power during start, those that never get it, and those (like me) that sometimes lose run power during start with the factory ignition switch. Sounds like you are one of those people who don't have run power while in start.

 

[Oldtimer]

 

[Steve83]

Sorry,meant to include that. 76 w/manual trans.

You should put ALL your truck's details & history (as much as you know) into your signature(<-click that) so it shows with each post, as this page explains:

(click this text)


Phone apps don't always show signatures, so you may need to switch to a real browser in desktop mode on your phone, or just use a desktop/laptop computer. Put your location (nearest city) in your profile &/or signature, & upload an avatar of the truck. Not all its details are relevant to these issues, but you don't necessarily know which ones are relevant, so just put everything in now. The more pics you post (NOT in your sig) of the truck, engine, wiring, labels, & undercarriage, the more likely we can help you.

And you're using the 3G alternator conversion diagram, instead of the '75-77 diagram. This page shows the connector & location:

(click this text)