Intermittently "dead" electrics

[StealthyBlagga]

Out of nowhere, my 1998 Explorer 4.0V6 is failing to start. The symptoms look like a totally dead battery (no lights come on when I turn the ignition key).

I took the battery (only about 6 months old) to be tested - it apparently needed a 45min charge, after which it tested OK and the vehicle started normally. I figured it might be a bad alternator, so I worked through the "not charging" test procedure in my Haynes manual. Everything appeared to test good ! Serpentine belt OK, no obvious problem with the alternator. The battery was giving about 12.5V with the engine off, and about 14.5V with the engine running (dipping only about 0.05 volts when the lights were turned on, but NOT recovering until the light was turned off again). All the fuses had continuity, both in the engine fuse box and in the passenger compartment fuse box. I backprobed the alternator just to be sure - got about 12V at terminal A, 12V at terminal B and 1.3V at terminal I, which the manual says I should expect (12V, 12V and 1V).

During all of my testing above (including removing and reattaching the battery connectors several times) the engine started normally every time, except once when I got the same "dead battery" like behavior. After checking the battery voltage (still 12.5V), and futzing with the battery cable (detach, reattach etc.), the engine resumed correct starting. Now I'm wondering if I have dodgy battery cables ? I have jiggled them pretty good, and see no sign of a problem (interior dome light stayed on during jiggling). The battery connectors did have some corrosion on them, but nothing terrible. In any case, I made a point of cleaning them inside with a wire brush early in my troubleshooting.

I'm kind of scratching my head on this. I'd rather fix this now than wait for the electrics to take a dump when I really need the vehicle. Have any of you guys got any additional suggestions/diagnostics for me ?

 

[BIGHVM]

Check the cables for breaks with a meter, one with clips and a tone would be good, also check for grounding problems, what you have done already leads me to believe that its nothing more than a smal break in the leads, either plus or minus from and to the battery.
To confirm run another set of cables to and from the battery alongside your current ones, if it never happens again, you got the answer!

 

[StealthyBlagga]

Thanks for the feedback Big... I'll follow this line of inquiry. By the way, how's the weather in Surrey ? I'm an ex-pat and lived for years in Kingston and Walton-on-Thames. The first thing I did when I moved here was buy a big truck and a muscle car .

 

[BIGHVM]

Its been cold here today, this week in the day time 6 degrees and overnight close to or below 0!
So you must be aware how hard it is to own an Explorer here now, fuel is around £105 a litre and road tax for us is hefty, also the congestion charge for anything over around 1900cc is going to have to pay £25.00 a day to drive into Londons congestion zone.................

I bet its a dream owning a big motor out there-why did you leave, like I never knew,(weather, house prices, cost of living, feel good factor).........NOne of thats here anymore mate, you did well what ever reason you had!

They wont take my Ex from me- NO WAY by tax, charges or any other means!

 

[StealthyBlagga]

... why did you leave, like I never knew,(weather, house prices, cost of living, feel good factor).........NOne of thats here anymore mate, you did well what ever reason you had!

My primary reason for moving was unusual, but certainly not unique. I have been a competitive target shooter, mainly pistols, since the early 80s. After Dunblane, and the ensuing election-year witchhunt that culminated in the pistol ban, I decided that Britain is no longer the kind of country I wanted my children to grow up in.

Actually, I do miss many things - friends, food, beer, good comedy - but there are lots of compensating factors here - great weather, low taxes, much nicer lifestyle, and better prospects for my kids. And, of course, the freedom I can no longer experience in the nanny state that Britain has become :frustrate.

 

[Yuba49r]

Check the little black relays.

Hello there,
I have a 1994 XLT Explorer, it was experiencing the same problems you are describing. I took it to Ford, I have a free return visit for this issue still, but i figured it out on my own. It only costs about $2 at the most. The little electronic box in the engine compartment has a bunch of these little (easy to break) relays from China. Just go to the Auto store, and ask for a relay for your model, the ones I had were about 1 inch square, the manual will show you where they are, in case you have difficulty. I had to replace it a couple times, as these little relays have a failure rate when new of about 1 in 6, lol. Which could be the problem...I wonder if Ford just buys these (charging the premium rate) things from China with their name stamped on them? I don't know, but I do know the service guys thought it was eeverything else but that, atleast I got new components out of it, even if I had to fix the real problem myself. Hope this fixes your troubles. Peace, Yuba49r