Can anyone inform me of what this does and is? Green wire off alternator voltage reg to this plastic tubular casing with the electrical connector inside. I opened it. did I break it?
Also, what is the purpose of this little rectangular box inline with solenoid black wire.
The wire fuse link on a harness from alternator burnt. I believe it did this because the connector at alternator shorted out. Got new alternator - comes with connector- Installed it and soldered new yellow wire link back on the two heavy black from the alternator and one yellow from voltage reg.

When done, I don't have high voltage to fuel relay. fuel pumps don't kick on.
Everything is back as should be. dumpfounded. Chilson has nothing on either part.

Thank you very much for your time.

 

That black tube looks like a fuse holder. Neither of those parts appear to be original factory parts, so it's hard to guess the reason they were put on your truck.

 

The Green/Red wire and the connector are factory. This is the exciter voltage to turn on the alternator. It should be hot when the key is in the Run position.

No idea about the circuit breaker in the second photo. It is not factory to the best of my knowledge.

Basic 2G alternator (aka fire hazard) diagram:

 

It solves a lot of guessing. When I turn the key on to run I do not have fuel pumps. I have 2.9 volts on the green wire coming out of voltage regulator (VR) with the key on run. I have 12 volts on black to the alternator. The white wire from stator to VR has no voltage till I try to start and rotate the stator part of the alternator. I'm thinking the green wire is damaged. When I check voltage at fuel relay I get only the low voltage and hear the relays click. But no power to fuel pumps.
I'm going to remove the harness ( again!!) and check the white an green wire. I don't know if you followed. The stator plug shorted and melted yellow wire to the solenoid.
As you probably know, this yellow wire from VR and two heavy black are fused together before solenoid. I fixed that and never examed the green. I suspect the green has to do with the keyed power to fuel pumps?

I think this truck was first a government vehicle. I am the second owner. Bought in 92 with 60k on mileage. Now I have 169K , Runs like new ( when running ) I've repaired everything as it wore out.
Like this site. Hope I can help others here also.

 

You may want to consider converting your truck to the third generation alternator. The second generation had a reputation for catching on fire due to the wiring, as you have discovered.
Do a Google search for more information, I've included a link that will give you more information.

https://www.ford-trucks.com/forums/8...-pictures.html

 

The Green/Red wire has nothing to do with the fuel pumps. It's sole purpose in life is to provide exciter voltage so the alternator "turns on".

If the fuel pump relay is energizing (1-2 seconds when cycling the key from Off to Run) and you have no power on the supply of the relay then you probably have another open fuse link. I have very little resources for EVTM for this model year truck to be able to tell you whereto look.

Ironic the wire is also yellow......and it hooks up to the starter solenoid terminal. It's always hot.

 

I wonder if the breaker was a cheap replacement for the fuel pump relay that runs the high pressure pump.

 

Doubt if it is replacing the relay, but if it is tied into the yellow wire for the fuel pump supply it could be an issue.

 

There is a slew of power wires coming off solenoid. I had to remove those wires to get at the alternator harness.
Since last spoke here I retested the alt harness. All good.
I kept reading the hot to fuel relay is always hot and I know it will not fire fuel pumps until the key is turned to energize the low voltage side of the relay.

Gawg darn it, I tested hot at relay again.

Started looking at fuse links, which are bound together next to battery heading into the main harness. I moved the battery and there is another wire I pained with blue dots so I knew it should be hooked back up to solenoid when I put the harness back on.
dam wire fell way down below battery mounting plate.
If it ain't right check again. Good five days of " what the hell" lol
\

thanks, men/ people. Have a wonderful safe holiday; I'll post my red neck truck soon.

 

FYI - 1990 EVTM



From Subford;

 

Been speaking with rla2995. Ya, all have given me much help. As the story goes I did not have fuel pumps. The reason I did not: did not connect the yellow wire to the solenoid to relays.
Now I thought all that would solve it. I connected the wire, Have fuel pumps. No start. I believe it is electrical.
I believe since fuel pumps kick on I have fuel. The way I read schematic is the PCM relay kicks in the ignition?
Both relays are new.
Could I have damaged the PCM relay during my search for power to relays?

This truck ran like new before this alternator fiasco. Turnkey, mil sec later running smooth.

 

Thanks Vinny!

 

Power for the ignition comes from the same ignition switch contacts for the PCM (EEC) relay. The trigger to fire comes from the PIP sensor inside the distributor. First check is if you have battery voltage (+12V) on the supply side of the coil when the ignition switch is in Run or Start position.


If the fuel pump energizes now, no.

 

FYI -

PIP – Dark Blue (398) – Pin #56/EECM

 

FYI -