Full Size Jeep Network

Buying a 73 j4000. Has wiring issues. Swapped with a 350sbc. None of the lights work. Po said sometimes they will work out of the blue but most time don’t work. He said he put a bulb in the twilight but it burned it out. No power in the cab, radio doesn’t work. Has all mechanical aftermarket gauges and the voltage guage doesn’t read. It has a switch and push button to start the engine, I’m guessing because of the wiring issue. Where should I look to fix this?

Well, you need a plan. Are you going to put it back to how it was from Jeep, or replace all the wiring? You going to hack it until it's driveable, or fix it all nice and reliable? There are several companies that make aftermarket "hot rod" harnesses that give you the wire and circuit. They expect you to route the wiring and terminate the wires for the various devices. The main advantage is lots new wire in many colors, which would be expensive purchased by themselves. Search for "painless" on this forum and IFSJA.

The original wiring does not have a fuse panel. Instead it uses a circuit breaker in the headlight switch and strategically placed inline fuses in the harness. The hot rod harness will have a fuse panel, which would be an upgrade.

'73 was the first year for the GM column, and you can get a harness that is meant for that column. Might be a good place to start since you already have an engine swap. That'll put back the key starter switch that locks the column, if you repair anything that's broken in the column.

A new replacement harness specifically for that truck does not exist. You can fix what you have and adapt it to the Chevy, if that's what you choose.

Do you have the '73 TSM? That contains the factory wiring diagram for '73. The diagram is also here https://oljeep.com/gw/elec/GW_wiring.html though the quality of the transfer is likely better if you get the actual TSM. Plus it will include info about the rest of the electrical system. I would suggest you copy the diagram double sized and get some colored pencils to follow the wires.

Basically it comes down to laying the circuits out on paper (however you do that) and going one circuit at a time until it's sorted. Multimeter, test light, whatever splices you prefer (solder, butt connectors, crimp connectors, crimper ... lots of opinions and variations here), some extra wire, test leads, etc. Get a good book on automotive wiring, or study some online if you need to improve your understanding of electricity.

What Tim said... amen.
I have the same year truck as yourself and had similar issues when I acquired it. Possibly some '73's have a fuse panel and some do not, as Tim stated. My '73 does have a fuse panel and it was a rusty mess. I removed the harness and soaked the fuse panel and all connections in vinegar for a few days which did cure some of the connection issues, but not all. You will find that almost all connectors will be greasy, dirty, and corroded. Clean all of these until you see bare metal then use a good quality dielectric grease on these same fittings. Most of my connection issues were at the firewall or bulkhead where the interior and exterior harnesses come together, pay close attention there.
If I had this to do again, I would do as one of Tim's suggestions and purchase a Painless universal harness like this:
https://www.summitracing.com/parts/prf-10102
Painless products are expensive, but have true value. They are made in the USA and will last with good quality connectors, insulation, and fine wire conductors.
Look at the mess I had, I'm sure yours is similar. You can see what a mild acid like vinegar can do, just do not soak it too long.

Oh, I am mistaken. Not what I remembered, but I focused more on CJs in the day. A '73 does have a fuse panel according to the wiring diagram on the Tom Collins site. That's an upgrade from '72, along with the locking GM column.

Kinda think that bulkhead connector and fuse panel is a GM part, repurposed from whatever GM designed it for. I recall painless has harnesses meant for GM cars that include the bulkhead connector with the new harness. Something to investigate.

JMO - I would fix what's there. I would make it as much like the Jeep original as possible, with some minor changes to accommodate the engine. I have a lot of experience with issues like this, and could sort it out eventually.

Note the bulkhead connector is there for fast assembly at the factory, not because there is some great value in having a big plug through the firewall while the car is in service. I have drilled out connections in these bulkheads and run a wire straight through. Makes no difference to the car, and is actually more reliable in service.

For now I would just like to try and get things working with the harness that is on it. Where can I find a wiring diagram for the truck?

https://oljeep.com/gw/elec/GW_wiring.html
https://www.rockauto.com/en/catalog/jee ... nual,10335
https://www.bjsoffroad.com/1973-Jeep-Fa ... _1050.html

Bought the truck, drives good. Lights are working but no blinkers or tail lights and key feels like it only clicks to acc, does not go back far enough for key to come out either.

It has an amc fuse panel, so I’m not sure which diagram to use? I think the problem is the key not turning all the was and not turning far enough back to remove it. The picture of the key is twisted as far back as it will go

The rear chamber on master cylinder is also dry because of a broken brake line where it threads into wheel cylinder. Will it damage the master cylinder if I drive it like that with the back chamber empty? Like tear seals or anything?

There should be a lever under the key lock that you press down. This allows the key to return to off.

If this is really a '73, the VIN will start with "J3". The number stamped in the front frame rail, passenger side, will match the sequential serial number that's the last of the VIN.

Again really a '73, refer to the '73 diagram on the Tom COllins site. Or buy the '73 TSM and it will include the '73 factory diagram.

The grounds are a typical problem for the lights. Suggest you go around and remove/clean/reseat all grounds with a new keplock nut or shakeproof washer.

84 prospector wrote: ↑Tue Mar 28, 2023 8:03 pm The rear chamber on master cylinder is also dry because of a broken brake line where it threads into wheel cylinder. Will it damage the master cylinder if I drive it like that with the back chamber empty? Like tear seals or anything?

You realize this is dangerous? Ok for around the yard, if that's what you want. Unlikely it's going to do any more damage to the MC. Add some fluid and let it leak out, to lube the piston. I'd just use the parking brake pedal to move around the yard.

Parking brake not hooked up, where’s the lever I have to push down to return the key back at?

All wiring seems to be working except for brake/signals and hazards. I pulled the bottom flasher out to see if there was power and power was on one side in fuse panel, even with blinkers off

I can’t find info online on what fluid it takes either. Dot 3 or 4? I have a bunch of 3 but don’t want to waste it if it takes 4. Has disk brakes up front drum rear with crossover steering and like a 5 or 6 inch custom lift. Dana 44s I was told front and back

84 prospector wrote: ↑Wed Mar 29, 2023 9:10 am ... where’s the lever I have to push down to return the key back at?

Next to the switch. Did you look at the column?

84 prospector wrote: ↑Wed Mar 29, 2023 9:34 am I can’t find info online on what fluid it takes either. Dot 3 or 4? ...

If you read the TSM, it's in there.
https://www.bing.com/search?form=MOZLBR ... equivalent
I don't have the '73 TSM, but you should now that you own the truck.

84 prospector wrote: ↑Wed Mar 29, 2023 9:14 am All wiring seems to be working except for brake/signals and hazards. I pulled the bottom flasher out to see if there was power and power was on one side in fuse panel, even with blinkers off

I don't see a question here.

tgreese wrote: ↑Wed Mar 29, 2023 2:26 pm

84 prospector wrote: ↑Wed Mar 29, 2023 9:10 am ... where’s the lever I have to push down to return the key back at?

Next to the switch. Did you look at the column?

Yes I looked at the column, I took a picture of it. The only lever I see is the gear selector lever. What lever are you talking about? Do you have a picture of one or guidance as to where it is at on the column?

tgreese wrote: ↑Wed Mar 29, 2023 2:36 pm

84 prospector wrote: ↑Wed Mar 29, 2023 9:14 am All wiring seems to be working except for brake/signals and hazards. I pulled the bottom flasher out to see if there was power and power was on one side in fuse panel, even with blinkers off

I don't see a question here.

It has power on one of those contacts that the flasher plugs into all the time when the blinkers aren’t even on. Is that Normal?

tgreese wrote: ↑Wed Mar 29, 2023 2:32 pm

84 prospector wrote: ↑Wed Mar 29, 2023 9:34 am I can’t find info online on what fluid it takes either. Dot 3 or 4? ...

If you read the TSM, it's in there.
https://www.bing.com/search?form=MOZLBR ... equivalent
I don't have the '73 TSM, but you should now that you own the truck.

That link isn’t working on my phone. Will dot 3 be ok?