Trying to sort out wiring 71 F100

[penguin327]

I just bought a 1971 f100 with a decent body and hacked up wiring harness. I hope to make this truck an everyday driver but am having some issues. The previous owner had removed the ignition switch an cut off the connector plug and left the wires dangling. He also bypassed the wires connecting the starter solenoid and was somehow hot wiring it under the hood to make it start. I am trying to install a new ignition switch and put the wires under the hood back like they are supposed to be. The wiring schematic on this site is a little hard to make sense of when you are trying to figure out the mess somebody else has made of the wiring. Any help or suggestions would be appreciated.

[68RGR]

If you can print the schematic large enough, you can use colored markers to trace each wire using the actual wire color. That should make it easier to follow the circuits.

You need a new ignition switch and a new socket for it. People do odd things to wiring and this falls into that category.

There are at least two types of ignition switches - One has spade lug type connectors and the other has round pin type connectors. Be sure the socket matches whichever type switch you get. Wire the switch using solder and heat shrink tubing if you can. That should be more reliable that crimp connectors.

Check rockauto.com or other parts suppliers.

If he was hot wiring it under the hood, he would have to energize the ignition and momentarily do the same for the starter solenoid to start the engine. It might help if you had another "unmodified" truck to check out so you could see the way it should be.

[Stealth69]

Mine was only slightly better than that and I gave up all hope and just bought the painless kit for these trucks and it was well worth the investment.

[penguin327]

Thanks for the replies. I have got the ignition switch hooked up and working. Now I have another issue. The battery is not charging. I took the alternator off and took it to Autozone and had it tested, it checks out good. I bought a new voltage regulator just to be safe but still am not getting anything to the battery, I am trying to trace the wiring using the schematic but am not having any luck so far. Any suggestions about what else I might look at?

[penguin327]

I got it figured out I think. My brother who is mechanic for the post office came over today and took a look at my project. Since the post office runs some vehicles over 30 years old he said he remembered something about a similar problem he had once. We checked the ground wire on the alternator and found it was in the wrong place. Then he looked at the regulator and hooked a jumper between pins 1 and 4 bypassing the voltage meter in the dash Eureeka! We now have 14 volts going to the battery! He said a lot of the older postal trucks had similar a problem when the volt meter went out and they couldn't get a replacement due to their being so old. Anyway it is fixed

[guhfluh]

Make sure it isn't overcharging at higher rpms and the field is actually switching.

[Corkwheats]

Mine was only slightly better than that and I gave up all hope and just bought the painless kit for these trucks and it was well worth the investment.

Wow. Dejay Vue! I have the exact same issue. Are the painless systems easy to install?

I'll check and see if they have one for a 71 F100.

Thanks,
Bob

[Camper Special]

the schematic wiring diagram in full size is super helpful
if you dont have access to a printer or plotter take the file to a kinkos or other print shop. it is worth it.
i keep mine rolled up in the garage!

[Corkwheats]

Thanks,

I was aware that there were good schematics (http://www.fordification.com/tech/schematics_h.htm) but which one would I use for my 71 F100. The year 1971 is missing from that page. That would certainly be a good thing to have.

Like the person who began this thread, I currently have a hot wire ran to my starting wire that must be turned on/off each time I run the truck. Also, my temp gauge & oil pressure gauge don't work.

I'd like to get this fixed this Summer.

Thanks,
Bob

[jdennis440]

Can anyone explain why there is no 1971 Schematic?

[sargentrs]

Found this over on "the dark side" in a post by somebody asking about a '71 diagram. Except for the glare from the flash, it's actually a decent photo. If I wasn't going to install an aftermarket harness I would definitely get one of these. https://www.classiccarwiring.com/1971-f ... g-diagram/

[Scuzzy_1250]

Hey dude I just did my 69s wiring. 4 owners of bad chocies had no brakes no blinkers no interior lights no speedo and it was messed up I was beating my head over it for a while. What I ended up doing is i scored a vergin wiring harness from the junk yard for 50 bucks and I spliced wire for wire color for color. All the bad wires. I have a book if you want message me and we can set something up and I'll get you a copy your still in the same generation so it should cross over.

[Thipdar]

This thread was dead for four years, then brought back to life...

Ok.

My only other comment is that you need to make sure you are using the schematic that speaks "gauges" if your truck has an ammeter, and speaks "Idiot Lights" if your truck has an "Alt Light".

The wiring is different between the two. The two different approaches have changed wiring at the Alternator, Voltage Regulator and Instrument Cluster.

For Gauges, use the '70 F350 schematic (yes, it should work well enough for a 1971, although there may be some wire color coding differences); for "Idiot Lights", you can use the '70 F100-250 schematic. If your truck is an F100, F150 or F250 WITH GAUGES, use the F350 schematic.

Most of the remainders of the schematics are equivalent.

[BennyGGG]

This thread was dead for four years, then brought back to life...

Ok.

My only other comment is that you need to make sure you are using the schematic that speaks "gauges" if your truck has an ammeter, and speaks "Idiot Lights" if your truck has an "Alt Light".

The wiring is different between the two. The two different approaches have changed wiring at the Alternator, Voltage Regulator and Instrument Cluster.

For Gauges, use the '70 F350 schematic (yes, it should work well enough for a 1971, although there may be some wire color coding differences); for "Idiot Lights", you can use the '70 F100-250 schematic. If your truck is an F100, F150 or F250 WITH GAUGES, use the F350 schematic.

Most of the remainders of the schematics are equivalent.

Your last post saved me hours more time trying to sort out my ‘69 F250 wiring. Using the ‘70 F350 schematic is exactly what I needed. Thanks!!!