Vehicle troubleshoot

[blackeagle603]

Something odd with my son's '93 Explorer electrical (5 speed, 4x4, 3.0L V-6). Pondering where to look next.

Today was the third odd power symptom or non-cranking event in the last couple months.

Working backwards in time:

3. Came out of class today and got no cranking. No clicks at all. Jumped it and fired right up.
Put battery on load tester and battery looks good. Alternator voltage looks right.
Terminals tight and clean and new lugs about year ago.
Took down to O'Riellys for their in car test and they called battery, alt and starter good.
Harumph...

He went to OReilly's cause battery and alternator are under warranty there. He had to replace both of them before his 2013 WesPac.
Put new battery terminal lugs on his cables last winter. Keeps them treated and tight.


2. A couple weeks back he ran inside 7-11 for a quick stop. Came out and radio presets had all cleared. Weird. Cranked up fine, normal cranking speed, didn't seem sluggish


1. Prior to that he came out to it in our drive and it didn't crank. Without any test or measurement he went straight to cleaning and retorquing cables then put on my spiffy new electronic sensing charger for a full cycle.

[blackeagle603]

Just talked some more. I got some of that wrong.

edit to #3:
today he noted when it wouldn't crank, the dome light was on, the radio presets were wiped and the electric door locks wouldn't operate. Had to use the manual entry.
That argues for low battery due to failure to charge or having been drawn down overnight. This was after his morning class.


edit to #2:
That reset after 7-11 stop was just a mile down the road from our place after he left in the morning. So minutes after a cold start.
Prolly parked it low on charge the night before. Or it had a drain on it overnight while parked.


edit to #1:
That first time earlier in the summer it died on a night time drive just as he rolled into the driveway after a 20 minute drive home from Claremont.
That time he did pull the terminals, clean, treat and retorque then run full charge cycle overnight.

So I guess that argues for a failure to charge of some type while operating.


Need to start thinking about loads drawing down while parked? Or something with intermittent alternator performance ?

[randy]

I'd start looking for current draws when shut down. (something common for amateur radio types from either not shutting everything down or on some radios with electronic "on/off" switches on control heads that shut off power to the control head but not the actual radios).

Any aftermarket units such as broadcast radio, stereo amps, GPS units, cell phone chargers etc.?

wife's old GPS unit would draw down the battery over a long weekend (3-4 days)

[blackeagle603]

Aftermarket stereo and amp...

[PawPaw]

Does it have a code reader port? Code readers are inexpensive and take most of the work out of troubleshooting.

[blackeagle603]

Need to see what that 93 will do with my readers. Don't recall if either of mine read ODB-1

[Aesop]

Either there's a drain on the batt when it's parked, or the alternator isn't getting a charge to the battery while it's running, which suggests a wiring problem rather than a major component problem.
Good because that's less $$, bad because finding a wiring fault on an older car can be a bitch.

Says the guy whose Astro van ate rebuilt alternators about every other year after Year 10.
I was on the verge of putting in a second battery charged by rooftop solar panel, for bombproof redundancy.

[blackeagle603]

at his desk in the garage cranking the Calculus homework (and waiting for that first GI Bill check to roll in next month).

passed him a meter, gave him a quick bit of ammeter gouge/review on testing for phantom loads with everything turned off/doors closed, in series with positive battery cable, etc. We'll see how he does with that later when he gets done with the fresh charge he's running.

Living the dream. 19 units doesn't feel like fulltime after NX flightdeck.

[Old Grafton]

Check the alternator. Physically. Pop the hood first thing after any overnight or long-period shutdown, and lay a hand(lightly) on the alternator (or use a thermal reader of your choice). If the alt is warm or more likely hot your internal regulator is shorted. Sometimes it can still charge, but it'll drain the battery once the vehicle's shut down. I had this on my F250 diesel last summer, and a Chevy Venture van previously.

[MarkD]

I had a similar problem once with the battery dying, but testing good and even being replaced. Turned out the lights next to the mirror on the visor were staying on, a little duct tape to hold the switch fixed it.