Another fuse box replacement ....

Just replaced my '03's fuse box again. The second fuse box was installed in January 2014 due to the typical melted fuel pump relay and PCM relay. It was manufactured in November of 2013 but still had the old 15 amp Osram fuel pump relay and other micro relays just like the original '03 fuse box did. The latest one was manufactured in November 2020 and has 20 amp Panasonic micro relays instead of the 15 amp Osram relays. So hopefully this one will last as long as the Expy does. We'll see.
The reason for the replacement was a crank / no start condition after short drives. (Disconnecting the battery, and reconnecting it allowed it to start...)
So far this has fixed the problem. I'll pull the old fuse box apart and examine the board and micro relays and see if I can find the problem. But it could be internal to the fuel pump relay and not visible unless I cut that little POS open. Which I won't bother with.


New Fuse Box for the '03 Expy .....





New 20A Panasonic JMM131 micro relays replace the 15A Osrams ....




Ford 3L1Z-14A068-AA Expy Fuse Box ...




The part number on the package is 3L1Z-14A068-AA.
But the part number on the fuse box itself is 3L1T-14A067-AA
The reason for the difference in part numbers is the addition of the power cable in the package along with the fuse box.

https://www.panasonic-electric-works.com/cps/rde/xbcr/pew_eu_en/ds_61210_en_jjm.pdf

And my wife calls me crazy for having a spare in the car at all given time!!
When one fails my plan was to just replace the relays to something more stable.
Thanks for the post and links!

You may have done this already, but you can measure the current draw of the pump and make sure there's nothing wrong with it. If the pump bearings are crappy, it may be drawing high amperage. But I'm sure you know that. Is this a known problem with these relays?

Trainmaster said:

You may have done this already, but you can measure the current draw of the pump and make sure there's nothing wrong with it. If the pump bearings are crappy, it may be drawing high amperage. But I'm sure you know that. Is this a known problem with these relays?

Click to expand...

Yes, the micro relay for the fuel pump was originally under sized for the job. By 2005 they did away with it entirely and put the control module back on the frame at the left rear wheel ( which had it's own corrosion problems...). Heavier duty replacement micro relays are available from Osram and Panasonic if anyone wants to replace just the relay. On this "built in 2020" replacement fuse box all the micro relays are the heavier duty Panasonic relays, not just the fuel pump relay.

That sounds like a giant PIA. Is this malady something common to all 2nd Gen Expeditions?

Mako825 said:

That sounds like a giant PIA. Is this malady something common to all 2nd Gen Expeditions?

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Just the 2003-2004 model years, where Ford used micro relays for high draw components. The fuse box swap out really isn't that bad, just plug-n-play stuff. The PITA is that Ford would design a system like this in the first place. By 2005 they re-thought the issue and moved to a full size control module that mounted back by the left rear wheel frame area, closer to the fuel pump. But that module went through it's own corrosion/failure problems too, until they came up with isolation mount bolts to keep the two metals apart and stop the premature corrosion and failures.

While on the subject, can someone post an Amazon link to a set of replacement fuses that worked for them for a 2003 Expedition 5.4 2v ?

I see a lot of mixed reviews on Amazon for replacement fuses.

AntC9120 said:

While on the subject, can someone post an Amazon link to a set of replacement fuses that worked for them for a 2003 Expedition 5.4 2v ?

I see a lot of mixed reviews on Amazon for replacement fuses.

Click to expand...

https://www.amazon.com/Bussmann-NO-.../B000DCN9BW/ref=psdc_6355932011_t3_B000BQYH3Y

Hamfisted said:

https://www.amazon.com/Bussmann-NO-.../B000DCN9BW/ref=psdc_6355932011_t3_B000BQYH3Y

Click to expand...

You’re a legend. Thank you, just bought em’ they should be here Tuesday !

So I know there is a bunch of people that like to replace the CJB (Fuse Panel). But remember that all you are doing is resetting back to the same potential problem being able to happen again. The circuit board was not designed properly to take the heat from those undersized relays. If the PCM relay is good, and you only fried the fuel pump relay, I recommend just putting an external relay on and wiring it in. There are videos to do this, but a lot of them suggest wiring it in improperly so that the fuel pump runs whenever the ignition switch is on. I have an 05 Expy and this is the proper way to wire in an external relay....

First... buy one of these external relay kits... its rated for 30 amps.
https://www.amazon.com/gp/product/B074QV54V1/

And one of these (mini fuse tap) ...
https://www.amazon.com/dp/B01LFXA5UA/

And you will need some inline power taps...
https://www.amazon.com/dp/B07WFPFY1C/



Then wire it in as follows...

Your relay has 5 wires. You don't need the center one. So all you need are the 30, 85, 86, and 87 terminals that correspond to the relay harness. 30 is power always on, 85 is a ground that activates the relay (it completes the pin 86 circuit), 86 is powered when ignition is on (engine running or not), 87 is power out only when the relay is engaged (this will go to the fuel pump)

The reason most videos are wrong is that they wire the ground to a normal ground. This means that the minute you turn on the car the fuel pump runs constantly. How its supposed to work is that the PCM has a ground going to the fuel pump relay that is only on 1.) when you first turn the ignition to the on position and its only grounded for the 2 seconds of priming then disconnects and 2.) When your car starts and it then needs constant power to the FPDM (Fuel pump driver module)

So what you want to do is to replicate that circuit that includes the ground from the PCM. Here is a way to do it that works the way it should...

First you need power to the new relay... fuse 9 (15) amps will work because its KOEO (Key on Engine Off).
Wire that Using a fuse tap to get power for the pump, fuse 9 (15A), wire that to 30 on your relay. Use a 20 amp fuse for the second fuse (put the 15 amp fuse on the lower socket the 20 amp on the upper socket. Basically you just made a new circuit.

On the C270A plug there is a red/yellow wire... that is Key on Engine off or on power. Basically power that only goes on when the ignition circuit is active. Use an inline tap to wire that to the wire that corresponds to 86 on your relay.

On C270B, there is a thinner guage black wire in the corner of the plug. This is ground from the PCM. On some years I believe its LT BLUE/Orange, but for 2005 its black. You can cut it or do an inline splice... I always opt for the inline splice for grounds. It is pin 12 of c270B and wire the harness side of it to 85 of your relay using an inline splice.

Now the relay should work, and you can test it before doing the final connection by turning the ignition on and you should hear a click from the relay. If this woks, you now just need to feed power to the FPDM.

The dark green/yellow wire of C270B feeds power to the FPDM... cut that and wire it to terminal 87 of your new relay.

Your car now has a better, and replaceable external fuel pump relay. Doing it this way will not fry your CJB and is easily replaceable if it were ever to fail again.