When the key is turned to run or start position, the entire electical system resets around every 5 seconds. This affects all dash lights, including the radio, and the engine electrical momentarily cuts out, too. This makes it impossible to drive or maintain idle on the engine without holding the brake pedal down.

This issue does NOT occur if the brake pedal is pressed down while the key is in the run or start position.

When the passenger compartment 5A fuse number 25 is removed (ABS fuse), this issue goes away, independent of brake pedal position.

In order to drive the vehicle, this fuse has been temporarily removed. Re-install 5A fuse number 25 to see the problem.

When the 5A ABS fuse #25 is removed, the dashboard abs light goes on, the speedometer does not function and the overdrive indicator continuously blinks off and on. However, the Excursion runs and drives great with this fuse removed.

The dealer diagnosed it and replaced the ABS hydraulic unit with a new one (the new ABS hydraulic unit is expensive). Now, they are telling me I need a new ABS module/Electronic Control Unit (ECU) ($888 for a rebuilt one from Ford). The dealer says they can get the Excursion running fine without holding the brake pedal or removing the ABS fuse, if they run the truck immediately after running a self-test on the ABS using the Ford dealer diagnostic computer. There are no codes being thrown into the vehicle computer.

I have already tried swapping the ABS ECU with one from a salvage yard with no change. I do not believe it is likely both the original ABS ECU and the one from the salvage yard would be broken in the exact same way.

Recent Events:
The wiring plugged into the alternator had recently caught fire. The fire was quickly extinguished.
The alternator, alternator wiring plugs, and some damaged vacuum tubing were replaced. The new alternator is functioning correctly, generating about 14.25 volts at the battery when the engine is running.
The starter solenoid was also replaced.
After these repairs to the alternator and vacuum lines, this electrical issue with the ABS circuit started occurring.

It is likely unrelated, but - I noticed there is a small parasitic current draw of about 300mA from the battery, unless the fuses for the interior lighting of the vehicle are removed. I think all vehicles are supposed to have no more than 20mA or 50mA current draw when the vehicle is not in use.
I have made sure the battery is fully charged (about 14.6volts) when the electrical reset problem is occurring.

Does anyone have any ideas or has anyone else ever had this happen?

 

What year and engine? What caused the fire? Alternator bad or wiring issue? Has anything been added to the truck recently or prior to the fire? The ABS system draws quite a bit of power and may be taxing a damaged wire beyond what it can handle. Was the main charge wire from the alternator damaged or replaced? It doesn't make any sense the issue goes away after testing the ABS system. Have you seen this happen?

I think it's going to come down to a wiring issue - I'd start checking wiring looms near the alternator or which share wire feeds to the alternator. You could even try just move all of the wiring around as much as possible to maybe move an exposed wire from touching something and see if the issue remains.

 

It is an early 2001 (11/00) with the 6.8L v10. I am unsure if the alternator fried because it was defective or if something else in the car caused the alternator to catch fire. The alternator that caught fire was a new aftermarket one, installed about a month earlier, used every day. I replaced the original Ford alternator because I was getting noise on my radio and at one point I smelled some burning. The fusible links to the alternator look and feel good with good continuity. Just the plugs and smaller gauge wires going into the alternator were fried at the alternator end. I replaced these and verified good continuity. The battery charge indicator and charging voltage are good, so these are working. The heavy gauge charge wire bolted into the alternator looks fine with no burn damage.
I have not seen the ABS self-test fixing the problem myself - it is the word of the Ford dealer. However, I do not see why they would lie about that. They seemed to think it was a valve sticking in the hydraulic ABS unit, and that is why they replaced it.
Could it be alternator wiring if the issue happens without the engine running, but with the key turned to the run position?
Your advice makes sense. There is just a lot of wiring in there to look at.

 

If the ABS pump has a solenoid sticking it most likely wouldn't cause a fuse to blow but will cause the ABS light on the dash to come on. If you smelled a burning smell prior to replacing the alternator I would assume you have a wiring issue and would start checking wires for damage. Did you notice where the source of the burn smell came from?

 

Problem solved! Since I had replaced the starter solenoid, at the same time I replaced the alternator wiring and alternator, I finally decided to try a different starter solenoid. After I replaced it, the symptom of the electrical system resetting with the key in the run or start position went away. However, the starter motor would not turn, and the starter relay would click. I could hear the ABS pump self test and fully cycle correctly. I unbolted and rebolted the wires connected to the starter solenoid and the battery terminals. Now the car works as it should with the ABS fuse installed. No more resets of the electrical system with the key in the run or start position without pressing the brake pedal. The car starts, idles and runs fine. THe speedometer is working. The overdrive indicator is no longer flashing. The ABS light is no longer illuminated. Too bad I spent over a thousand dollars at the dealer to get a perfectly fine ABS hydraulic pump replaced, when the problem was a bad wire/connection to the starter solenoid. I ended up replacing both battery cables with new Motorcraft cables - the positive, which connects to both the starter solenoid and starter motor, and the ground from the battery to three different ground connection points with the final connection connected to the underside of the engine, not too far from the starter. The terminal ends on the original cables were fine, but the wire ends into the terminals were corroded real bad (green powder on the positive wire, and brown powder on the negative wire). I am just glad it is working now and had nothing to do with the electrical fire. I hope this helps anyone else running into the same issue.

 

Nice job!!

 

Dont know if this is related, went to start the truck battery was totally dead, replaced it and ran fine allthough speedometer needle was jumping everywhere and just stopped working. Went back to start it and readio was playing byitself...turning off, then playing again?...now the truck wont start at all, battery is fine?..wierd. Ant suggestions?

 

As the OP states above, crazy things can happen if you have high resistance in the wiring (e.i. Corrosion)...If you have a bad ground the power will go through other circuits to find a way back to ground... Check your battery cables + and - for corrosion (the green stuff) and if they look swollen there may be hidden corrosion under the insulation anywhere along the cables...
I hope this helps... Good Luck!

 

Thank you...I think you are right..."orca" spends most of her time on the beach surf fishing and the last time that happened I was stuck over night in a storm and salt walt/mist was dripping from the inside so corrosion did in fact kick in..problem was finding a new/used fuse box apprently Ford no longer stocks them and it was an act of god to finally find one from a wrecked Excursion. Mine is aa 2000 and they are NOT interchangable with any other year...V10...if anyone knows any differently I am all ears as this could cut my hunting season short

 

The radio turning itself off and on combined with your speedometer and starting issues sounds more like symptoms of a corroded or wet fuse box or GEM. I would check there first. If the starter motor is not turning over, check the starter solenoid/relay mounted in the passenger side of the engine compartment, not far from the battery.

 

Thank s again pretty sure your right...does anyone have a a couple of good sources where I can find one?...someone told me they think the box from a 350 super diesal would work for mine as well?