What year?

 

At least on a 70 w/o air, could be for the heater blower motor ( 14g OR) . Would have to give yr,make, model with or w/o air to be sure.

 

Like Undee says (name??) the orange wire could be just tucked in there and not used. Typical on an A/C car that uses an option harness.

 

sorry, 68 malibu w/ac. 307/th350.

 

Like Undee says (name??)

Greg Underwood

 

The orange wire goes to the heater blower motor terminal.

I was going to post a similar topic about which firewall harness wires go to to the starter solenoid terminals marked "S" and "R" (the yellow wire and the thicker purple wire).

Can someone verify this for me?

Thanks, Charles

 

Purple = S, to ignition switch
Yellow = R, to coil, resistive wire bypass if you're still running points. If you're running an HEI the yellow should not be required as the resistive wire should have already been replaced with a standard wire.

 

Thanks, Finally. Just a follow-up question though.

I decided to switch from a points distributor to an HEI sometime AFTER I had
already installed a new wiring harness (for standard points). If the yellow wire is no longer required at the starter due to a new HEI, then should I just cut it off at the other end where it connected to the old points distributor?

Thanks again for your help, Charles

 

I'm not sure how it's hooked up now. It would normally go to the + side of the coil along with the resistive wire. You should have a standard wire from IGN in the fuse block supplying power to your HEI/coil. Is it a coil in the cap or external coil? Whatever the case the yellow wire is redundant now, assuming the HEI is wired properly, and it is only hot while cranking.

Bottom line is if the HEI is properly wired with 12v from the ignition then the yellow can be removed. How you go about it is up to you, cut it off, disconnect, etc.

 

I am going through this right now and am a little confused about the yellow wire...

Ok so the yellow wire and resistive wire are connected to go to a coil normally. I have HEI with coil in cap.
--If I simply remove the resistive wire, will that yellow wire supply the 12v to the coil?(I suspect not)
--If not, and I simply do not connect the yellow wire to the starter solenoid; Can I simply replace the resistive wire with a normal wire (in the same junction block location) and expect this wire to supply the correct 12v to my coil?

As it is now, I routed a wire inside my car to one of the poles by the fuseblock. Getting rid of this would be superb!

 

I am going through this right now and am a little confused about the yellow wire...

Ok so the yellow wire and resistive wire are connected to go to a coil normally. I have HEI with coil in cap.

The yellow wire ( comes from the "R " terminal on the starter solenoid) was meant to be used only with a points distributer. It supplied 12 volts to the points when cranking, the resistive wire cuts the voltage back while running. HEI's don't like reduced voltage.

--If I simply remove the resistive wire, will that yellow wire supply the 12v to the coil?(I suspect not)

Yes, but only when cranking.

--If not, and I simply do not connect the yellow wire to the starter solenoid; Can I simply replace the resistive wire with a normal wire (in the same junction block location) and expect this wire to supply the correct 12v to my coil?

Yes

As it is now, I routed a wire inside my car to one of the poles by the fuseblock. Getting rid of this would be superb!

A buddy did this ( his was wired from the ignition terminal on the fuseblock) and he would get no voltage when cranking ) We just ran a wire from the "R " terminal on the starter solenoid to the HEI, BAT terminal and it cured his starting problem. Maybe not the right way to do it but it worked.

 

A buddy did this ( his was wired from the ignition terminal on the fuseblock) and he would get no voltage when cranking ) We just ran a wire from the "R " terminal on the starter solenoid to the HEI, BAT terminal and it cured his starting problem. Maybe not the right way to do it but it worked.

I hooked mine up to the acc pole I think. Took me a while to figure out why it wouldn't start on the IGN pole. So...
If I keep the yellow wire going to the starter, AND replace the resistor wire (going to IGN I assume) I should get 12v cranking from the yellow, and 12v from the new wire while running?
Why did they engineer this resistor wire to get too little voltage while cranking? In fact, why DOES this wire get a cut in voltage while cranking?

 

When your car is running your electrical system should be at 14.5v. Supplying this high a voltage all the time would burn out the mechanical points pretty quickly. The resistive wire is meant to provide a lower voltage ~9v while running.

While cranking your alternator is not working and your battery voltage drops some due to the large draw from the starter. The voltage from the resistive wire will be even lower than the normal ~9v. The yellow wire from the starter supplies full battery voltage to the coil while cranking for a little hotter spark. Once running the yellow wire is disconnected and the resistive wire supplies the coil voltage. That's how it was originally designed to work.

With an HEI they like to run full voltage all the time, no points to burn out and you get a hotter spark. You can trace the resistive wire down to the junction block and pop it out. You can buy lugs at a parts store to make up a new wire, 12g is recommended, and completely replace the resistive wire with a new wire. If you do it this way the new wire should be hot while cranking and while running and the yellow wire can be removed. If you add a new wire to the fuse block that is hot while running but not when cranking then you need to leave the yellow wire in place. Or find a spot in the fuse block that is hot while cranking and running.

 

Well, that explains it! Thanks!