what is the EDU 1 fuse ?

[spurmaker]

there is a 25 amp fuse between starter and fpump that is a 25 and keeps blowing, the oweners manula does not say what it is other that EDU??

[DmaxMaverick]

Welcome to the forums!

EDU = Electronic Distribution Unit. AKA: the fuel system driver (distributor, like on a gasser, for lack of a better term). The EDU is located on the passenger side valve cover, silver box (looks like a computer hard drive), with electrical connections, and fuel line in/out connections (cools the electronics). It's divided into 2 banks (left/right), #1 and #2.

If it's continually blowing the fuse, check the harness and connector for damage, corrosion or exposed wires. The EDU receives a low power current from the PCM (Powertrain Control Module), which is amplified/relayed to drive the injector solenoids, simply stated. If the amp is bad, it can overheat, overload, and blow the fuse. This should normally cause a DTC, and the SES lamp should be on.

[spurmaker]

I believe the problem is there, I removed the wire harneses, and put back and put in a new fuse and it fired for just a second,then the fuse is blown....what now? THANKS!!!!

[Kennedy]

The EDU's seldom if ever fail, but I think I'd try replacing it and see what happens. They should be cheap from salvage as there's really no demand near as I can tell.

On edit: Which engine is this? LB7 or LLY?

[spurmaker]

I don't know which engine it is, o4 6.6?

[DmaxMaverick]

Look at your VIN. The 8th digit indicates which engine series.

1 = LB7
2 = LLY

[spurmaker]

it is #2

[Kennedy]

Now that changes everything. Start tracing the engine wiring harness particularly in the area of the EDU, alternator and where it is tied down. The LLY for some reason has more than it's fair share of harness issues. My 2005 had an intermittent issue due to bare wires in this harness.

[spurmaker]

when I put a new fuse in and crank I see smoke (a little) coming from the wire harnesses going into the EDU but it quickley blows the fuse, I have stripped the shrouds back and do not see any bare wires??

[DmaxMaverick]

Strip back the loom and remove all the tape in the area where you saw smoke (a good distance in both directions). Replace the fuse and repeat. If you don't see where the smoke comes from, you should be able to feel the hot wire(s) if you're in quick enough. Also look for damaged, burned, discolored or hardened wire insulation.