Dug a little around in my archive and found a service manual for 00-04, so following is the same diagrams for a 00 Exped 5.4, more or less the same but use these to find correct pinouts.

 

Apparently, I did not have a good ground when I used the test light on the #30 fuse.
I just went and checked with the multi-meter and I have 11.5v on both sides. (key to the "on" position)

Pulled the diode shown in the diagram (#501 as shown in the pic in post #34) and when I set the multi-meter to "ohm". At 2k I get "1." If I set at 200 I get "1 .", if I set at 20k I get "1 ." - Not sure what it all means.... Sorry - like I said earlier, electrical is like math to me. (more of a punishment) LOL

Currently, it stopped raining for a bit- Looks like a t-storm on the way soon. Any other ideas before I have to call it for rain??

 

After trying to teach an old dog a new trick, I looked up the testing method here:
How to test diodes using a digital multimeter

My multi- meter does not display "OL" on any setting... Not sure if I'm doing something wrong or not.

Using the "diode test mode" I tested with positive lead on one side and negative on the other and got these results:
First way was fluctuation- then settling down to ".653"
Second way was "1."


Sorry for all the confusion! I've never really had to fool with electrical so it's a huge learning curve. And I'm not yet sure what I'm learning!

 

double post...

 

Again, just to verify. You used your test light with fuse #30 in the CJB in place, so I'm guessing you just probed each side of the fuse with your test light.
That tells me you have battery voltage TO the fuse, and battery voltage THROUGH the fuse, but it doesn't tell me that the output side of the fuse is getting good contact with the output side of the socket.

Pull the fuse out and inspect the legs of the fuse and the socket to be sure there is no green stuff (trademark!) stuff growing in there.
Put the fuse back in and go re-run the test for power at socket 86 of the PCM power relay.

If power at socket 86, go ahead and start the truck up.

If still no power at socket 86, pull the PCM diode and see if there is power to the input side of the diode socket.
If no power no power to the diode socket, repair the wire from fuse #30 to the PCM diode.

If the PCM diode input socket has power, switch to you ohm meter and ohm out the circuit from the diode output socket to the PCM relay socket 86.
If it reads open repair that circuit. If it reads very low resistance, replace the diode, and go ahead and start the truck.

Good Luck

 

Ok. I went back out. I pulled the #30 fuse. It's clean. Put it back still 11.8v on both ends with key in "on" position.
Only .95v at the power leg of the PCM relay.
Pulled both diodes and tested. Both appear to be good with .653/.640 and 1./1. respectively.

I tested the diode sockets. On #501 (which appears to be the one for the PCM- I get 11.8v) on the other one #502 (not sure what it's for, I get .03v- nothing)

Quote:

If the PCM diode input socket has power, switch to you ohm meter and ohm out the circuit from the diode output socket to the PCM relay socket 86.
If it reads open repair that circuit. If it reads very low resistance, replace the diode, and go ahead and start the truck.

Not sure I understand how exactly this test is done... Are the wires connected?

 

I'm trying to make some sense of all of this so I went and took more pics (Remember this is for the 2000 Ford Expedition XLT 5.4L)-
The red with green stripe is the wire that is getting power at the #501 diode. (it runs into the loom)

 

If you look at the lower right side you will see 2 wires that are tan with a yellow stripe. These are from the other diode. (#502- according to the lid)

 

Followed one of them into the loom and the other one here:

 

Lower right where finger points to black relay is where it goes. Not sure if this is anything or not. (not sure if there was anything in the empty space next to it before or not)

 

 

 

 

 

Don't worry about diode 502, that has to do with the A/C clutch.

So you have battery voltage at the SOCKET for the PSM relay diode (501).
That means the circuit from fuse 30 to the PCM diode is good.

But when you go to pin 86's socket you only have 0.95 V,
so we are dropping a lot of volts between these two points.
Take the diode out of the circuit and the PCM relay out of the circuit.
Therefore there should be no power between these two points.

Set your DMM to ohms, put one probe in the diodes output socket,
and the other probe in the PCM relay pin 86 socket.
If you have over a few ohms, that is the resistance between the diode socket and the PCM relay socket 86.

The wire that runs from the diode output socket to the PCM relay pin 86 socket is a white with light blue striped wire under the BJB.
Take a look under the BJB and see what has happened to that wire.

If the resistance reading is near 0 ohms, the whit/light blue wire is good,
so the problem must be in the diode.

Do you remember when you last turned the key to "ON", did your CEL lamp light up during the bulb check?