Note that pin #2 of the self test plug is only a ground if the computer has a good ground with small black wire with a green stripe at the NEG post of the battery.
In other words from pin #2 of the self test plug the path is to the computer connector pin #J1-46 into the computer and then back out the of computer on pins #J1-40 & #J1-60 to the NEG post of the battery.

J1 in the below diagram is the computer connector.


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Ok guys, just came back from the shop. Here is what happened I grounded the tan/gn wire to the attach bracket for the cruise control by the hood hinge. turned on the key and nothing. So I got out the test light and I didnt have a good ground. so I reground the wire and checked to make sure I had a ground and tried to start. The starter clicked like the battery was low and then everything went dead. I have no power to the starter, the head lites, the panel, nothing. I checked the battery and it reads 12.77 which is plenty. What the hell did I do?

 

Bad battery cable connection.

Check and clean both battery posts and connectors. If you have those bolt on replacement battery connectors, trash them and replace with new battery cables.

Check and clean the battery connection at the solenoid. This is the main junction point for the entire +12 circuit. If you are replacing the positive battery cable, this is where it will connect to. Other wires attached to this point are the main battery feed to the entire vehicle, (via fusible links).

Make sure the ground cable connections are clean and tight at the engine block and fender.

 

Could I have destroyed the solenoid? How do I test the solenoid?

 

Very unlikely the solenoid is destroyed.

What have you got to test with? Assuming at least a test light, start with the battery, directly on the terminals. Light on brightly? If so, turn on say, the headlights. With the lights on, do you still have a bright test light across the battery terminals? If so, move the ground clip of the test light to the connection at the fender. Probe the battery +. Keep moving towards the solenoid connection. Start with the battery clamp. No power at the clamp, dirty connection, same at the solenoid. When you pass a section where the light goes out, you have found your problem. Keep in mind that you need 2 connections to make power flow. battery + and -. Same procedure for finding bad connections in the ground circuit. Once you have a connection to the engine block and the body, you can start assuming that the various accessories will have a good ground connection anywhere in the vehicle assuming that the wire remains intact as installed. Keep in mind the ground will not always connect properly through a painted and bolted connection or rubber mounts. That's why there may be additional bond straps between, say, the engine and firewall. Turning and leaving the lights on provides a load test that may reveal high resistance connections.

Don't over think the easy stuff here. Check your primary battery cable connections first.

 

So I went back out this morning and put on new battery cables, and a new fuse able link and got all my power back. So I grounded the tan/gn wire from the fuel pump relay and turned on the key. the whole relay and plug and the fuse able link melted. The ground wire that I used to ground melted all the way to the truck. I think that was a major short. Any ideas why that would happen?

 

Looking at the diagram below when you ground the tan/light green wire you are only closing the coil of the fuel pump relay and the full battery voltage should drop across the coil of the fuel pump relay.

It sounds like maybe the yellow wire to the fuel pump relay was shorted to the tan/light green wire.

I have and others on this site have grounded that tan/light green wire hundreds of times with no problems. That is also how the Ford shop manual say to test the fuel system.

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I agree. I have read that several places. Could I have the wrong relay? I have purchased 2 relays and they are black and have 5 pins. The harness has only 4 wires. I assumed that the relays were universal and worked in other relays

 

The power relay should have had a brown bottom.
The fuel pump relay should have had a green bottom.

Some have replaced the factory relays with the newer Bosch relays.
The top relay is the newer Bosch relay and the bottom relay is the factory relay.


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That really did not answer my question which is could i have the wrong relay? I know what the factory relays look like. these are aftermarket w/5pins.

 

The top relay in the diagram above should be the one you are talking about.
The numbers are put in the wiring diagram above to show how to wire in the up grade to the Bosch relays.
This is a common mod as the 87-91 trucks have a problem with the wiring under the relay sockets.

I do not know how else to respond to your question.

 

ok, Im not sure if the harness plug that I installed is the right one for the truck. Maybe the relay doesnt fit the plug. I dont know. Can you tell me what the bosch relay is... part # maybe?

 

Sure, he is a link to them:
List: Search for 'fuel pump relay' | O'Reilly Auto Parts

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Why is this so hard? Get a relay, probe fuse block to find 12V+ with key on,use a fuse tap and a jumper to activate the relay. wire relay to battery, put relay output to fuel pump wires at the tank switch. fuse relay to battery power.
No inertia switches, no oil pressure shutoffs, no screwing around. By the OP, this truck will never see the roads again, so why would one need all the road-safety crap ford put in these? You could do the wiringlisted above inabout 20min.

 

Not the best link. No Bosch relay and no plug. I tried to search Bosch relay plug and got no results.