1968 Wiring Drawing Error

[Wildergarten]

My Green Truck fried it's in-dash harness and I'm in the process of replacing it with a spare I had. What do you know but they are not the same despite being out of trucks from the same year! (One was a Camper Special, the other was not.) So... while I was sorting all that out, I noticed a problem in the FSM wiring diagrams.

On page "22-SPECIFICATIONS" in the 1967 Factory Service Manual used for 1968 trucks, there is a drawing of the Emergency Flasher wiring diagram, for all models.

The upper two of the two lines coming out of the EMERGENCY FLASHER SWITCH on the right side of the drawing appear to have reversed color designations in the middle of the long flat horizontal runs as drawn. The upper 18YE (yellow) line on the drawing goes to the upper flat triangular three-input connector receptacle with nothing but 18LG (light green) lines connected to it (with one exception I get to below). The 18LG line out of the switch goes to the lower flat triangular three-input connector receptacle with nothing but 18YE lines connected to it.

There appears to be a second error on the drawing. On the ACCESSORY CONNECTOR drawn at the bottom of the page, the 18DG coming in from the left I suspect should have been 18LG, as that is the connector with all the other wires light green. I looked at the connector itself in the truck and there was no dark green wire coming out of it; it was light green. In fact both sets of yellow and green triangular receptacles I have to resolve had wires corresponding to the color of the receptacle.

In addition to all that, the wires on the firewall side had all been painted pine green.

Given that this was such a simple system, it gives one all sorts of "confidence" in the wiring diagram for the rest of the truck!

[Jims68]

The '68 had a "Supplement" Service manual. That has the '68 wire diagram in it which is different than the '67. Not sure if the Flasher Diagram in the supplement... but I can email you the '68 Wire diagram if you need it. I'll look tomorrow to see if the supplement has a flasher diagram in it.

[Wildergarten]

The '68 had a "Supplement" Service manual. That has the '68 wire diagram in it which is different than the '67. Not sure if the Flasher Diagram in the supplement... but I can email you the '68 Wire diagram if you need it. I'll look tomorrow to see if the supplement has a flasher diagram in it.

Thanks for the offer! I have that supplement, but when I got to the section on "Electrical" it said things were substantially the same. So I'll let you know if I can't find it as I hadn't looked at the Specifications section in the supplement. It sure as hell wasn't wired the way it was drawn.

I have found another error in the 67 drawing, this one is on the main 100-200 series drawing just below the fuse block where it shows a 10PK wire that just ends with two #16s coming out of it... as is NOT reflected in the harness I'm looking at. This is just goofy when I'm trying to adapt one truck harness to one that is obviously different. Then there are the weird choices such as showing the fuse block from the side with the fuses as opposed to where the wires go, forcing one to go through "flipping" it mentally to figure out what to put where when it comes to getting two #10s down to the buss for enough current to the fuse block. Somebody had cut off the high current wires where they come out of the main harness and I know all too damed well might be inside.

I'm just trying to make this truck run until I get the new one built. I don't have time to redo the whole damned thing. It has brush and equipment to haul so that we can get to logging.

[Wildergarten]

The '68 had a "Supplement" Service manual. That has the '68 wire diagram in it which is different than the '67. Not sure if the Flasher Diagram in the supplement... but I can email you the '68 Wire diagram if you need it. I'll look tomorrow to see if the supplement has a flasher diagram in it.

I'm looking at it, thanks. They integrated the flasher into the main drawing which now covers two pages. It's totally different. They did fix both problems I identified in the '67 diagram.

[Jims68]

I also scanned BOTH of those pages for the '68 and then joined them both on ONE page. I have your email... I'll just send it. OH and it's also on the "CD" as well . May be worth printing it out?? And yes, I saw that the "Electrical" mentioned going back to the '67 book, but in the "specifications" the newer wire diagrams are there. Weird right? I did not see a flasher page in the supplement.

[Wildergarten]

I also scanned BOTH of those pages for the '68 and then joined them both on ONE page. I have your email... I'll just send it.

For the record and benefit of others, I'll repost here my reply to you.

Thanks, Jim. What a mess! I have no idea how anybody would do a museum grade restoration with these source documents!!!
The first image [you sent] has the same mistake as what I posted about.
I’m noticing all sorts of goofy things about the systems in this new drawing that make no sense to me.
A 30A fuse for the horn, as feeds 16AWG wire? No way, and I know the horn line is bigger than that. No relay? I’ve seen them on these trucks. Where is it?
I don’t see any sign of a relay for side marker and clearance lights as shown but trace the feeds from the ammeter.
Look at the middle disconnect plug. Note the 18YE and 18DG lines in the middle of the plug and follow them to the right. Yellow becomes dark green and vice versa. Yeah, right. So it goes. They say, “shoot the engineer and go into production”?
I’m getting ready to ignore a lot of it, give the fuse block more amps from the battery terminal or buss bar on the ammeter, ring out the blower and wipers, make sure the lights work, and just wire in what I need.
They should have made the guy who drew it wire a truck accordingly, but I bet what happened is that somebody wired it to make it work, sent the guy in with the pencils a bunch of sketches, and told him to finish the manual.
Thanks again, I do appreciate you sending me that, if only because I can print it to take it out with me without screwing up the book.

[soopernaut]

A 30A fuse for the horn, as feeds 16AWG wire? No way, and I know the horn line is bigger than that. No relay? I’ve seen them on these trucks. Where is it?
I don’t see any sign of a relay for side marker and clearance lights as shown but trace the feeds from the ammeter.

Single horn trucks did not have a relay and dual horn trucks did.

Side marker lights and were not present on most 1968 light-duty trucks, just reflectors. I'm not sure about 1 tons, but of trucks lighter than that, only Camper Special trucks had side marker lights that year . Clearance (roof) lights were not that common either, so probably not shown in a standard wiring harness drawing.

[Jims68]

Single horn trucks did not have a relay and dual horn trucks did.

Side marker lights and were not present on most 1968 light-duty trucks, just reflectors. I'm not sure about 1 tons, but of trucks lighter than that, only Camper Special trucks had side marker lights that year . Clearance (roof) lights were not that common either, so probably not shown in a standard wiring harness drawing.

Well there's some really good info I didn't know about the relay and DUAL horns!!

[Wildergarten]

Single horn trucks did not have a relay and dual horn trucks did.

Yup, the '67 I parted had a relay on the core support and dual horns mounted on each side of the engine compartment on longer shock mounts directing the sound through the radiator. I kept those horns and shock mounts.

[BigBlockTrucks]

Single horn trucks did not have a relay and dual horn trucks did.

Yup, the '67 I parted had a relay on the core support and dual horns mounted on each side of the engine compartment on longer shock mounts directing the sound through the radiator. I kept those horns and shock mounts.

My late year 65 has dual horns with the relay. One horn mounted next to the radiator passengers side the other bolted to a hood hinge bolt on the drivers side. The relay is mounted to the firewall.

[Wildergarten]

My Green Truck fried it's in-dash harness and I'm in the process of replacing it with a spare I had. What do you know but they are not the same despite being out of trucks from the same year! (One was a Camper Special, the other was not.) So... while I was sorting all that out, I noticed a problem in the FSM wiring diagrams.

OK, so I found more that was strange and wonderful in the factory wiring as to how and why the under dash harnesses were not the same. First was this 15A circuit breaker. I am guessing it was for power for a trailer battery.



I was wondering why, when I took out my fried harness, I obviously saw the red "Accessory Connector Plug" in the firewall. Yet there was no red accessory connector in the spare harness I had on the bench. That had me concluding that I needed to cobble the spare harness I had together with the accessory plug from the fried harness I'd just removed because those wires were still OK. That meant I had two sets orf the triangular yellow and green receptacles that needed a jumper between them to make the wire sets electrically common so that the turn signals and flashers would work (as they now do). It was all sorts of not fun ringing this out.

THEN, as I was yanking what was salvageable off the harness, I figured out what had happened. The reason there was no red accessory plug was this loose firewall connector that has male connectors on BOTH sides with the wire colors carefully painted on it. I actually recognize this sort of thing as the kind of adaptation manufacturers make when something molded won't work with specific options packages or is temporarily unavailable, but I sure as hell wasn't expecting it, nor was there any note that such adaptations were a factory twist on trucks as delivered.

Most entertaining, not.

One big improvement for the future is that I've had this bit of an oven deck lying around the property I'd made into a stand for drums of used steee. I suddenly relized that I could use it for accessing the engine bay, and you know, I really like it.

[Jims68]

You may not have had much fun figuring this out, but it's interesting nevertheless to the rest of us! That stand sure did make it easier to stand over the grill I'll bet!

[Wildergarten]

You may not have had much fun figuring this out, but it's interesting nevertheless to the rest of us! That stand sure did make it easier to stand over the grill I'll bet!

Yeah, it was NOT fun. I still have issues with the system, but I'm on the way out. I jsut wish I'd understood it going in, but the documentation was no help there. The trick will be in keeping it from damaging itself being jerry-rigged together.

I was once a manufacturing engineer, so I do know how this kind of thing tends to creep into reality. Problem with the method is that once the plug gets dirty, one doesn't know that the colored stripes are there on the engine compartment side, and from inside it's awfully dark up there with a flashlight. That had to be a pretty serious paint they got to stick to rubber for 50 years in that environment, but somebody got a job painting stripes on connector bodies. Amazing that they could sell those trucks so cheaply with that kind of task being necessary.

The stand is awesome. I may lengthen the legs a bit, but with my new winch bumper I won't need it to reach to the firewall from the front. I'm almost (was) 6'0" and it was still a hassle. I'd climb the bumper and kneel on top of the core support. Pretty sucky trying to think while in a position that precarious in near 100° heat. So thanks for the vote, I'm just trying to help here, staying within my limits. It's weird building one of these things wondering if the creeps in Sacramento will continue to allow me to get the gas to run it. Glow-bill warming and all that.

[martincom]

on the main 100-200 series drawing just below the fuse block where it shows a 10PK wire that just ends with two #16s coming out of it...

In my experience,the pink wires are for dome, map, glove box and underdash lamp power feeds. As none of these were standard equipment on Sweptlines, until the later years, they were optional. As such, the pink wires connected to a flag 1/4" male terminal on the load side of a battery bus fuse, on the backside of the fuseblock. When a truck would have multiple options, such as door switch dome lamps and an underdash lamp, they're may have been a short tail exiting the fuseblock, splitting in two, with female bullet connectors.

[nutz]

sounds like you got it
i find that in to many makes the wire drawings are like a basic guild not always what you have

[Wildergarten]

In my experience,the pink wires are for dome, map, glove box and underdash lamp power feeds. As none of these were standard equipment on Sweptlines, until the later years, they were optional. As such, the pink wires connected to a flag 1/4" male terminal on the load side of a battery bus fuse, on the backside of the fuseblock.

The pink 10PK line from the bottom of the fuse block on the '67 drawing feeds the red 16RE line to the stopping lamp switch and a red 16RE line to the B2 terminal on the headlight switch. Nothing else. There is also a pink 14PK line from the I2 terminal on the ignition switch through the firewall to the 12V side of the ballast resistor. The line to the dome lamp is yellow. There are a number of changes in wire colors between the '67 and '68 drawings, particularly on the high-current buss line with splices on it. So while that generalization of yours may be true in other years, I wouldn't consider it as a generally applicable guide.

I ended up cutting open the harness in the engine bay because the alternator line had got so hot before it was abandoned that it had melted the tape in spots. It had also fused or formed its insulation to some of the other wires. So I have another job to do. I ordered a momentary contact push button SPST/NO switch for the dash to run the fuel pump to prime the carb before starting. I'll be putting my notes on that matter in the build thread. One other thing with the Carter pressure switch for a fuel pump is that it has no grounded terminal under pressure. That means one must either add a second pressure switch for the oil pressure idiot light or reverse the circuitry for the light, putting the source on the post for the fuel pump and change the bulb fixture to the grounding flavor usual on the instrument panel. I had gobs of the latter so it was easy.

So then I powered it up, and what do you know there was no power to the pump! The buss bar on the ammeter where I'd taken the voltage for the SPST dash switch was dead. So the replacement for the damned ammeter that started this mess is bad too. I have one more spare, but I'm contemplating gutting the new truck instrument panel as we speak and going to a voltmeter after this morass.

[nutz]

do you know what started the melt down

[Wildergarten]

do you know what started the melt down

No. The way it all began is when I hit the key and got a click. I knew the battery was good, so I started tracing connections. When I got back into the dash I noticed a spark when I checked one of the ammeter connections, both of which were pretty rusty and loose (like they'd been running hot for a long time). So I took out the ammeter and cleaned up the threads, installing with new nuts and washers.

Like an idiot, I put on the battery terminal without looking for a spark and what do you know but about a second later I noticed the smoke starting to rise. Pulled the battery terminal and the ammeter was a toasted mess. Then I noticed the harness which was smoking hot too. Most of it was OK, but I wasn't taking any chances.

This truck already had the "unprotected alternator wires through the firwall" routine with the high current wires into the harness and at the starter relay diked off (bad sign). So I had my suspicions about the harness already. I'm guessing it was pretty well fried before any of this started just like the alternator wire in the engine harness that had been abandoned too. I'm just lucky this didn't happen sooner.

So I pulled the harness and popped in another one I had from one of the trucks I had sacrificed. Found another ammeter in the drawer, (I have two more, both in panels) and popped it in. I still have the fiberglass backplate with the buss bar off the fried one, so I might just try that, albeit with a good bit more caution. I'm not into putting more good after bad into this truck while I need to focus on the new one. This one just has to run to keep things going on the property while I do that.

For the high current alternator/battery wires (and anything else I was running through) I got a 1/2NPT PVC bulkhead union as an insulator and turned it off to shorten it a bit, chamfered the holes, etc. It was a quick compromise dealing with a hazard that gives me the heebs.

I had put on the electric fuel pump because the engine had roasted the cam lobe and that floating pin for the mechanical pump, and I've seen that on 3 of 3 383 engines I've had. I'm NOT going to run an electrical pump without an oil-pressure switch. At least the ignition line that will run it is fused. So the extra wires are for the pump, the oil pressure idiot light and a 12AWG line to replace the red the (ignition + fuel pump + electric choke) line as the 16AWG factory line is a bit skinny for the current current capacity of those added demands.

So then I realized I was wiring in the dashboard push button switch to prime the carb to a hot buss bar with no fuse. OOPS. So perhaps it was a good thing the buss bar on the ammeter had lost contact (I'm thinking of soldering the connection). Details, details. It was NO fun getting the switch into the panel next to the brake switch light, but there was a hole already there. Tightening the nut on it was, well, nutz (if you're reading this). Oh, but if that nut loosens it shorts the switch! If I loctite it? Leave it off? It is a push button and the fit is good... "...and lead us not into temptation... " So it goes.

[Wildergarten]

.

[nutz]

putting the dash in from my 65
just cause i like the color and like the smooth look without the dash pad ,and its warped anyway and dash was cut for radio
so the 65 harness is pretty much unmolested ..think ill use that one ..but will know better when they are both out
hate the glass fuses seen to many get corrosion and poor contact
seems like there are only 4/5 fused circuits so after reading this seems like i should use a small under hood box for a couple of things
maybe a nice 40 or 50 amp main before it goes into the cab
will be easy enough to run the amp gauge threw that maybe with a circuit breaker
and changing to electronic ignition so not blast resistor
i hate extra loose wires
ill try to post what i find when i get there