Headligjts dont work.. and bright light switch by foot has no plug ?

[candymancan]

You need to isolate the sender from the gauge, and test separately. The TSM has a chart that shows steps to diagnose gauge problems.

Suggest you look at the '82 TSM on the Tom COllins site. Section 1-L. The '82 book much better about the gauges than the '76 book, and they work the same.

There is a lot written about this topic in old posts.

The sender is connected to the gauge by a pink wire. There is a connector at the sender, and the sender must be grounded through the gas tank steel to the chassis.

If you lose connection between the sender and the gauge, or lose the tank ground, the gauge will go to empty.

The connector at the tank could be bad. The tank ground could be bad. The is a connector to the chassis harness under the driver's side footboard/floor.

You can ground the pink wire, either at the bulkhead connector (stick a pin in the back of the connector and ground it) or at the chassis harness connector (under the driver's floor). Don't leave it grounded for long, but grounding the sender wire should make the gauge move to full.

If the gauge goes to full, the problem is in the wiring or tank ground. If not, move closer to the dash and try grounding it again. Eventually you'll either find the wiring problem (gauge moves) or condemn the gauge or cluster.

Interesting. So how is my tank grounded if i painted the entire thing. And painted the strap ? Only the two bolts thr strap go in are welded to thr nee bed floor which is grounded to the frame its bolted too i assume.

Are you saying there is a connector at the tamk itself which i obvioualy know about as i repaired the tank by welding it etc.... and another below the drivers floor. Why two connectors for the same one wire ?

I wonder if my tank being painted and the strap is causing this issue. Need to figure out how to ground the tank.

Can i drill into those side lips on the tabk where the two parts are pincjed together and screw a snall screw and grounding wire to it and the frame. Or would that cause a leak. Dont think itd leak. Its just the flaps sticking outside the tank itself around itself

[candymancan]

And while were at it.. i jist got back from my car show.. and drove home at nigjt. First time with it. Sijce the ligjts are fixed.

But i nkticed when driding the dash lights all em and the headlights were glowing brighter and dimmer none stop even at a constant speed.


?

[candymancan]

Also tgrease your ammeter bypass for ab alterbator upgrade

Your way to me seems like some uneeded steps are done. Or uneeded extra connections

Instead of power from thr starter solenoid going through the yellow wire.. and then spliced into the red wire. Then the red wire into the cluster. ( then cut the red wire in the engine bay and run it to the battery from the alternator ) causing this wire to have two diff colors....

Couldnt you also just run power through the red wire on the solenoid. To the cluster wires it goes too. And leave the yellow wire completetly disconnected.

This leaves the fusible link still on the red line to thr cluster protecting it. Elimating the need to have two extra connections in the dash and two color wires.... Yellow to red. Then red to cluster wires....

Then just run a larger ga wire from the alt to the battery.. adding a fusible link in between. Or inline fuse or breaker.

Am i making sense here. Youre way is using the 10ga red wire you cut.. to have a larger alterbator charge the battery directly saving wire. I guess 10ga at just 1-2 feet is plenty for a 90a alternator. I guess your way.. allows for use of the existing fuse link on the 10ga wire from the alt to battery.

But creates more connections/failure points and mis colored wires in the dash that are also not procted by any fusible link anymore


I guess both ways work. My way just requires the need to make new wire and a fuse for the alt battery. Or hell you could use the yellow wire if you wanted and just add a 14ga wire in between for a fusible link.

Allowing the dash to have less conections and color coded wiring

[tgreese]

The replacement sending units come with a wire for ground that you can use or not. The plate of the sender is the ground connection, and the sender is connected to the tank by the locking ring, then bolted to the chassis - this should be a good ground, but maybe not.

I presume the chassis harness plug is there for the assembly line. You don't _need_ a connector there, but that connector makes the wiring modular - the truck uses a different chassis harness from the wagons - and separates the chassis from the cab at assembly time. They would assemble the chassis, then cover it with the cab and bed.

You realize that removing the ammeter leaves an air gap between the ammeter terminals? Current goes through the ammeter like it was a wire connection. You could connect the red wire to the solenoid and the yellow wire to the alternator, if that pleases you. Then you could remove the ammeter and not splice the ammeter terminals together.

The effect of the 10 ga wire with a 90 amp alternator is something you can calculate. I recall 1000 feet of 10 ga wire has a resistance of about an ohm? Say 3 feet, I^2 R = 24 watts. Should be ok in free air. If it worries you, you can go larger, but I expect you'd need to go a lot larger to cut the heating by much.

[tgreese]

If you want to reduce the heating of the alternator wire, you could substitute a 6 ga wire and cut the heating in half. A 6 ga wire has about half the resistance of a 10 ga wire. Or you could double the 10 ga wire, running two strands in parallel. This would have the same effect as the 6 ga wire. You'd need to use terminals that will accept the ends of the pair of wire.

For the ammeter circuit, it may be helpful to think of sources and sinks of current. The dash and lights is a sink (the load) and never a source. The alternator can be a source, but is never a sink. The battery can be either a sink or a source, charging and discharging resp. This explains why the alternator and dash are on one side of the ammeter, and the battery is on the other.

If you don't care about the ammeter action, any wire arrangement that connects the load and the alternator to the battery will work. If you meet this condition, any variation you prefer will be fluffery.

[tgreese]

Yes, you could ground to the edge of the tank, as long as it's far enough away from the tank proper. The best ground would be to solder a wire or tab to the plate of the sender, then run a wire to the chassis. A Weller soldering gun should have enough heat for that.

I would measure the resistance between first the chassis then the gas tank and the pink wire going to the tank sender. The sender has some measurable resistance regardless of the tank level. If it's an open circuit, you have a bad ground or the sender wire is corroded/broken/open or the sender element is kaput. Divide and conquer.

The big chassis connector is a prime target. I would look at that first. The bulkhead connectors seem to be pretty reliable, since they are filled with anti-corrosive dielectric grease. All of the chassis connectors are not.

[candymancan]

Alright thxks for thr info.

Far enough away from the tank proper what do you mean by that ?

Thanks for all the info. Ima work on cleanibg the few ground points i have found and probably add new ones to the chassis and frame as well. And upgrade to my grand waga old 90amp alternator. I think 10ga is satisfactory for charging with only 1-2 feet from a 90a alt. Just was curious. As for using a 14ga fusible link i assume you showed on there. Is that really needed ? Is there one on that red line already is that why you did it that way ?

Also what is K on your diagram ?

And see if this stops the surging in voltage i expeirenced last

[tgreese]

Out on the edge of the lip; not in close to the tank.

Splice K on my '82, between the 14 ga fusible link and the 10 ga yellow wire. Also splice B. The smaller squares are splices.

The fusible link is already there in the factory harness, between the solenoid and splice K. Prevents the car from catching fire if there is a wreck or other catastrophe. Protects the wiring from the battery.

The fusible link in the red wire is something for you to install. You should read the post that goes with the diagram. Again, it protects against a car fire if there is a short in the alternator or its wiring.

With one long wire through the ammeter to the battery, you need one fusible link. Make two connections to the battery, and you need two fusible links. Cheap, easy, reliable insurance.

[candymancan]

So if i use the yellow wire to power the cluster as you did. I will be using the existing 14ga link on that line ?


And the red. Just go to autozone get a link and put that between the alt and starter solenoid. Sounds easy enough. Just wanted clarification. I didnt realize the yellow wire going to starter solenoid from the ammeter had a link on it. I thought the red line from the alternator to the cluster is the one that had it.

Seems the red one should have been the link as its closest to the alternator. Not the yellow from factory i mean

[tgreese]

Yep. Check the wiring diagram - it's there. Or look in the wire bundle.

Yep. I used the Bussmann kit: https://www.amazon.com/Bussmann-BP-FL-1 ... B001BXR9L8 - Standard, Pico, Dorman all have a similar kit.

The link goes as close to the battery as possible, to protect against shorts after the link. In the original config, it must go there.

[candymancan]

Whats so special about fusible link wire anyway. I read its just silicone insulated wire.

If thats the case i have spools n spools of that wire. Not sure if i have 14ga ill have to check but i have 10/12 16/18. Etc

Couldnt i jist use the silicone wire i got to inline the 10ga charge wire. Seems like a waste of 5$ for a 3 inch long fuse link wire if its jist silicone insulation on it that makes it special.

I bought this wire specifically to resist heat and fire when i wired my 90s offroad kc style lights. Sounds like perfect fusible link wire to me ? Ypu can take a small hand sized butane torch to it and it doesnt singe like normal wire does

[tgreese]

Yeah, probably ordinary wire with fireproof insulation. Can't say if that's silicone insulation or not. Primary wire is typically insulated with vinyl (PVC) which melts before the wire fuses. Fusible link has special insulation. Fusible wire is pointless if it starts a fire when it melts.

Up to you. Trust your judgement?

[candymancan]

Ill just use what i got its rated 200c.. thats really hot.

Also the alternator i got is a 12si 94a delco that i put on my 90 gw fir many years before i put a 150 on. The 12si has a plug for two wires. The J10 has a single wire.

Im trying to research if its possible to put the 12si in. Or not. Seems simple enpugh.. connect the exciter side to a 12v ignition source like the ACC post in the fuse panel. The other side connects to the charging post. Is that all i need to do ? Do i gatta disconnect the regulator or something on my J10 or just wire the two wires like i mentioned

Or is this not compatible. ?

[candymancan]

Also seems the 9ld alt uses a diff bracket to mount than the 12si.. damn.

But the old alt uses a giant spacer. The old alt top post is 3 inchs exact. The 12si is 2 inchs. I have thick metal spacers. Dont see why i couldnt use those to make the top post 3 inchs like the original. The top post hole is slightly snaller so id have to drill it out a tiny bit larger... The aluminum isnt as thick as the original either. But i think itll be fine.

And the bottom post lines right up to the bracket.

Your opinion ?

Also the two boxes on tje fender by the battery do those or one of them need unpligged i think the rectangle is the regulator right ? Do i just unplug that after wiring the 12si in or what ?

Ive searched for hours now i cant find and answer

[tgreese]

Maybe someone has some experience with this. AFAIK all the SI alternators have 4 connections - battery (charge wire), exciter, sense, and ground. A '76 comes with a Motorcraft alternator and regulator. Not the same as the Delco SI; "Systems Integrated" with the regulator inside the alternator. Seems blindingly obvious if you read the TSM.

[candymancan]

No need for the smart ass comments man you need to chill.

I already know its exterbally regulated. I need to know how to bypass that square regulator box. Or do i just unplig it all together. So the 12si doesnt fight with it. Thats all really. Ill do the mounting mods myself and see if it works or not

[tgreese]

Discard the regulator. Rewire by copying the wiring diagram from a '76 with a 258. That engine uses an SI alternator.

[candymancan]

Ok thanks. Its easy to wire a 12si i got that down... I just dunno what to do with the 4 wire harness that went onto the external regulator. Do i just set it asside ? Thats what im asking.

Tge wire diagram wont show me what to do with an external regulator wire harness i dont think

[tgreese]

A '76 with a 258 has an SI alternator. Follow the wiring diagram.

[candymancan]

https://theamcforum.com/forum/wiring-a- ... 12493.html

Found this also. None of the wires on the plug are needed. So i can just unplug and toss the regulator in the parts pile. The orange wire on the plug can be used as an exciter wire. Supposedly though so i dont need to run a new wire to the acc tab on the fuse panel.

Ill try that first and see if the vehicle shuts off. If not, acc feed it is. Just wanted to be sure the 4 pin plug to the regulator wasnt needed