1990 7.3 IDI F250. Posted elsewhere, but I think this is the correct place to ask this question, sorry mods.

Just got brand new battery cables made up, new alternator, found all the info I could off the net, wired it up as indicated, however the instruments on the dash seem to be stuck half way ( The fuel gauge and temp mainly ), and when the ignition should go on, nothing happens.

Additional notes of consideration, the previous owner wired up a start button on the dash, and there is a bulkhead starter on the inner fender as well - all was working fine before. The white stator wires are crossed/joined, and I have yellow/white and green/red wires going to the matching yellow and green wires on the loom, old voltage regulator and wires to the old alternator are removed now ( but I still have them to hand ).

Any thoughts ? My guess is its a wire wrong or a wire I am missing or should not have cut, the instructions I followed were from here ....https://www.ford-trucks.com/forums/90...ring-help.html , and here ....
Piece of cake 3G alternator upgrade - Diesel Forum - TheDieselStop.com




EDIT/ADD: This is a dumb one, but looking over some other threads, is the red wire I'm running off the + off the back of the alternator meant to go to the battery + or the start solenoid ( in my case the bulkhead starter button ? I'm getting mixed ideas from different places, and I have a bulkhead starter button, not a starter solenoid, solenoid being on the starter itself ( unless I reading that wrong being in the U.K, things are worded a bit differently, sorry ).

 

Run the large output wire directly to the battery + terminal, or to the large terminal on the inner fender solenoid that goes to the battery +. Stop and look at this and trace the wires. You will find the large lug on the inner fender solenoid(this might be what you are calling "bulkhead solenoid) goes directly from the solenoid to the battery +, so as you can see it's the same thing, so either place will work for the large output wire from the alternator.

Sounds like you have the green/red wire hooked up correctly. I don't think you should hook the yellow wire to the loom yellow wire. The yellow wire from the alternator(it's really yellow/white?) is the regulator sensing wire, and this wire can be jumped right over to the large output lug on the alternator, or you can run it along with the large output wire, and then tie it to the same point as the large output wire(the battery + or the solenoid + as described in the previous paragraph). Wherever you want the yellow to pickup the voltage info from the truck.

This leads me to another question. Where did you get this yellow wire in the loom? Did you cut it off of something on the truck?(like the solenoid?). If so, you need to put it back where it belongs. I have a suspicion this yellow wire you found was a major power wire for the truck, not the yellow wire that went to the old regulator.

 

Thank you for the speedy reply ! Really appreciate it !

I'll go out in a moment and try out the suggestions. The yellow/white wire going from the alternator plug/pigtail I have is currently connected to the solenoid + lug - sorry I said loom didn't I ( heat does that to me, we have a very unusual heat wave at the moment ). The green/red is connected to the green red on the loom. main feed/hot wire going straight to the battery.

I had a few 'extra' wires clipped in on different palces from the previous owner, a lot were redundant. But I'll take a look at the old loom and trace what's been cut as it does seem very much like I have chopped something I should not have.

Heres hoping ! Back a bit later Thanks again !

 

I've had another go, but still nothing. I keep thinking " it must be something so daft and simple but I can't see what ". So I'm adding some pics.

I moved the yellow wire over to the Battery + and did anything else I could think of ( checked the fuses as well ) but still no ignition at all, no relay clickings either.

( I had to extend the green/red wire with the black/red you can see ).

 

forgot to add - if anyone can confirm if the wiring looks to be correct or not, that will help. Though if it is correct then I might be looking at a dead ( new ) alternator which will be a kick in the tailpipe to say the least

 

Update .... HELP !!

I've re-wired the yellow/white and light green/red wires, checked everything.

But what I should have checked and did not until now ( as it gets dark, typically ) is I have no power at all, no ignition, no headlights, blowers, nothing.

I installed brand new battery cables at the same time, so tomorrow I'll go check everything as I am starting to think ( now I know there is no power at all ) that an earth or mains able is to blame as I can hit the start button in the cab and the solenoid clunks on the starter but no turning, but the button is wired in separately ( being after market ).

But if anyone has any thoughts, or could confirm anything that would be great, thanks ! Flying blind at the moment and I need to be back on the road asap !

PS ) everyone who replies to my threads/posts always gets a good rep hit from me

 

The alternator has nothing to do with having power to the rest of the truck(as far as function). The alternator can be bad, and it still should crank and start if the batteries are good.

What has happened; a wire has been disconnected or cut. It is common for the old alternator output wire to be tied into the power wiring going into the cab. So you may have cut that wire and killed the truck.



Look at the picture above. It's for a 89 truck, but should be very close to your 90 also. See the "starter relay" on the right side? All those wires hooked to that one connection, those are the main power feed wires. As you can see the old alternator output wire was connected there also.

The above picture may be a little hard to see, but starting from the top;

-the first two wires(black/orange) feed the glowplug system power.

-Next down is the red. That is the fat red wire that feeds the bat + to this terminal, and thus all the rest of the wires bat + powers all the time.

-Next is the yellow that feeds fuse #1. This powers the fuse box.

-Next is another yellow that feeds the ignition switch

-Next is a black/orange that feeds another fuse.

-Next is a red wire that feeds a brake controller if your truck had this option.

-Next is another yellow that feeds marker light relay if you have a dually pickup.

-Next is another yellow that feeds the EEC. This is the computer, which you will have if you are running a fuel injected gas truck, or a diesel truck with a automatic overdrive tranny(this tranny had a special computer for the diesel to control it).

The last one on the bottom is the old alternator output wire(black/orange).

P.S. I just thought of another likely scenario; If you have been doing wiring without disconnecting the batteries, and happened to brush a hot wire against some metal, you may have burnt out one or more fusible links. All the above wires have rubber things in the wires called fusible links that act like fuses. If you pull on them and they stretch or look melted, they are burnt in two. The store has new ones(the stores over here do).

 

Thanks for the detailed info, thats really appreciated !

As it happens I woke up this morning at 3am after having a dream about a battery cable I don't remember seeing. I sent my old leads off to a company to make news ones modelled on the old, they forgot one lead - the one going from the battery to the solenoid ! ( Knew I'd miss something totally stupid like that ).

So did a bit more tidying and attached the old cable between the battery and solenoid and all is well - on that part.

However, to my sadness I seem to be getting nothing from the new alternator which I had to import from the states so returning it ( if they would even accept it ) will be a nightmare.

If I'm doing anything wrong, please let me know, but all I have its a digital multimeter tapping off the battery terminals. I have 12.5 volts in each battery, increase in rpm all the way to 3k + gives no change. Put a load on and the batteries dip to 12.1, and again, revv away with no change at all.

Thanks again, you were right on the nail with the cut cable / missing cable route !

Shame I'm no further ahead though

 

Double check that you have 12v at the output terminal of the alternator with the truck off. I see you have a large black box in this wire(is this a fuse?) so this will make sure that's good.

With the truck off, make sure you have 12v on the yellow/white wire going to the alternator.

Make sure your black/white jumper is ok.

With the truck off, but the key in run, make sure you have 12v on the green/red wire going to the alternator.

 

Great stuff ! I'll get on to that tomorrow, thanks - really appreciate it because when its not working properly its hard to take it anywhere to get 2nd opinions !

Oh and the black box is a mega fuse ( in its holder ) so you are correct ! :-)

 

Checked over things, I re connected the white/black wire/s ( stator wire ? ). With ignition ( run ) on I've got whatever the batteries are carrying on the + post of the alternator ( in this case 12.35volts ), green/red wire 0.1v.

The results are the same at any point down the line's I probe with the multimeter, and I just checked with the engine running as well, still the same. So 0.1v on the green/red ( remote/activation wire ? ) is not good then ? I wonder where that leads me on to now

 

That green/red comes from the instrument cluster. My 89 has a little picture of a battery that lights up when you turn the key to run, but do not start the truck. If your little battery picture is not lighting up, I would investigate why.

You could also for test purposes, take the green/red, and hook it directly to the battery +. If it starts charging, then you know you are on the right trail to the problem.

 

One battery light bulb later, and all is well ! I do not know whether to laugh, cry or celebrate !???

Thanks a million ! I'm getting about 13.8 idle and 14.5 at about 1200 rpm upwards.

Going to throw in a theory, I thought my GP controller is dead ( replaced the relay, no change ) there is no chance that the dead battery light bulb would effect the GP controller in anyway ? Its just I recall when testing it I was getting less than 1 volt ( a lot less ) to the plugs etc. They are fine on the manual heat set up I put in, but then thats off a different circuit. Possible or not, in your opinion ?

Thanks again ! I'm pleased its not something major, wish I had brains to think of this before - thankfully I have well learned people on FTE !

 

A low battery will definitely affect the glowplugs and the controller. I have never checked the system, but it has been said by people in the know that the glowplug system can draw over 150 amps when activated. If the battery is weak, this will draw the whole system voltage down. The brain in the controller needs some voltage to work.

But truth be known, I do not like the automatic system. When everything is new, it works well. When the wiring and the connections get old, it starts getting finicky and will not work right sometimes, since the controller brain works on the current draw of the glowplugs. Any bad connections will confuse the controller brain.