Weird intermittent dying issue.

[blakshukvw]

My 99 explorer has had an issue this summer while driving after about 20-25 minutes. What happens is first the abs light will come on, if I lift off the throttle it will go off. If I stay on the throttle it will stay on and eventually then the speedo will start swinging erratically. Again if I let off the throttle, it will return to normal. If I stay on the throttle at this point eventually the truck has a hard shut down. Once it does this, it will coast a while and eventually power back up and proceed driving ok. It will most likely do this again, but not all the time.
I’ve replaced the Interstate battery with another battery and all was good for a few months. Now issue is back again. Interstate battery tested fine with no issues but I wasn’t convinced the heat of summer wasn’t exposing a bad cell. Well apparently that want the deal. So the issue is back with a different battery.
I know that the vss can cause abs light and swinging speedo but I’ve never heard of it causing this hard power cut.
Thinking issue with GEM module maybe or wiring? Anybody have suggestions?

 

[blakshukvw]

I forgot to mention that last night I checked the charging. Alt was charging very reliably even when the abs light was coming on. Last night while driving it started to flash the abs light and I pulled over to start checking the charging. I could induce the abs light to come on in neutral just revving the engine but with the lights on radio on ac on and door open o had a strong reliable 12.8v. I think I should have the alt tested for amperage output though.

 

[J_C]

?? How did you check the charging?

With the engine running and a good battery and alternator, you should have around 14.4V not 12.8V.

Since you have replaced the battery, odds are your alternator is bad.

Again if I let off the throttle, it will return to normal. If I stay on the throttle at this point eventually the truck has a hard shut down. Once it does this, it will coast a while and eventually power back up and proceed driving ok. It will most likely do this again, but not all the time.

However this part is a bit weird, like you might have an intermittent wire shorting out or a bad connector somewhere. I'd start by unplugging, inspecting and replugging the two large harness connectors under the hood, probably up top towards the back though I'm not sure on a 5.0L.

Having the alternator tested does seem like the best first attempt, especially if it is the original alternator or an off-brand replacement. If it's bad, replace it and see if the other problems go away.

 

[blakshukvw]

Most vehicles won’t charge at 14.4v with all of those consumers on.

Checked with a digital voltmeter.

 

[blakshukvw]

I meant to type 13.8v not 12.8v.

 

[blakshukvw]

So issue returned tonight. Seems to be happening more frequently. It started flashing the abs light a few blocks from home but was still running. Never had a complete shut down. Got home parked in driveway and went inside for about 30 minutes. Went back out to run some tests. Open the door no interior lights. Key in ignition, nothing. I mean like there’s no battery in the truck. Get out close the door scratch my head a little. Confirm the battery cables are tight. They were. Open door and it has interior lights again. Key in everything comes on cranks and starts.

 

[EB4X]

From what your describing sounds like maybe a break/short in your 'drivers door wiring harness / boot' ....granted your ignition wiring does not route through there but sounds like something temp/cutting out/ shorting (due to random harness short movement) - opening/ closing door could be your culprit agitating damaged wire...? (Red flag is when you mentioned no interior lights- the door open/dome light sensor wiring runs through this harness) ....I've heard of issues with these harnesses causing problems....semi-common on Jeep GC's as well....Have second person there and try opening / closing door part way while trying to start and or running....at least rule it out....

 

[blakshukvw]

How do you suppose the door wiring is suspect? The issue is complete power loss to the entire vehicle not just no interior lights. Complete and utter power loss to everything, and yes that includes the interior lights but also everything else that runs on 12v.

So I think this is a heat related issue. Since the outside temp has dropped there’s been no issue. This makes me think it’s a high resistance in some wire. Obviously resistance goes up with heat and this issue is only a problem in excessive heat. What a nightmare to diagnose this has been.

 

[J_C]

^ While temperature could play a factor in an intermittent connection at some electrical connector, it is not going to be a matter of resistance going up with heat like you would see in wire. That tends to take far more of a temperature difference. Consider that whatever the problem was, it survived all the summers till now.

If you can't replicate this parked at home, then I would consider getting one of those cigarette lighter voltage meters to see if you observe a voltage drop when things go wrong, though if it isn't going to do it again until it gets hot out, you may be waiting till next summer.

Did you ever get the alternator checked? Have you tried taking the battery clamps off, cleaning that, and cleaning the connection at the alternator?

 

[donalds]

2nd gen issues? Try this first!

 

[blakshukvw]

I have removed the battery connections numerous times. There’s never been any corrosion on the terminals or connections at the battery. Clean as new. Replaced the original alternator with a known good one from my previous X. Haven’t tested the old one but I’m confident it’s ok. This isn’t an issue of a non charging alternator. If it were the battery would just go dead. That isn’t what happens. This is intermittent complete power loss like the battery is completely disconnected one minute and the next it’s just fine.
I feel like it’s a power supply issue to the main fuse panel next to the brake booster or coming out of it. But why? I’ve checked the connections to that fuse panel but never been able to do so when this issue is happening. Probably will have to wait until next summer unless this issue gets worse to the point that it does year round.

 

[gmanpaint]

If it isn't something obvious, and instead of taking a chance getting stranded and a tow charge....

Take it to the dealership and let them hook it up to their special diagnostic software. They can test the entire system for any issues, and offer you the repair once found, or tell you what's wrong to do it yourself. Last time I did that, it was $75. They fixed a couple recalls that hadn't been done for free too. Lol

 

[410Fortune]

or they will charge you $100 for the compute hookup and tell you "could not duplicate the issue"

I suspect your battery cables, there seems to be an issue on the OTHER SIDE of the cables, like where the ground wire leads to from the battery...check the grounds
Could also be a dead short in some other power wires

when it happens you lose ALL POWER to the whole vehicle and then it comes right back sometimes...the only way this can happen is bad battery connections usually at a ground wire unless the + side of things is causing a dead short.
Your battery is held down tight right?

 

[blakshukvw]

Battery is tied down correctly.
I see the small ground right on the core support right above the battery and i see another ground on the front of the motor near the oil filter. Is there another engine ground? A bigger one perhaps that I don’t see? That’s a pretty small engine ground wire if that’s the only one. Is there another ground point for the battery cable under the tray?

 

[gmanpaint]

Main ground cable goes from the battery to the frame, then to the engine block with a 4 awg cable. Nothing under the battery tray.

There is a known issue with these cables corroding from the inside, and you can't see it just by looking at them. Cable should be somewhat pliable, and not overly stiff. The stock battery clamps used on stock cables are terrible, and promote corrosion after a while.

 

[blakshukvw]

I’m aware of the corrosion you mention. My 01 has 260k on it and the wires are corroded under the insulation but that truck never gave me any problems. This new x has 110k and no corrosion at the cable ends. The factory battery terminals have been removed and replaced with what appears to me like possibly a dealer installed replacement. I’ve never seen anything quite like the,. It’s nice terminals with approx 12” wire leads that have metal blocks at the end that you shove the factory cable into and then tighten a set screw to lock the cable into it. Then a thick rubber boot covers that junction. The positive and ground are this way with the ground having an extra wire with an OEM like ground connection made at the core support. Again, I’ve been an auto tech for a long time but I’ve never seen these cables before. They appear to be OEM or dealer quality.

I know there were some wiring issues with a lot of X’s that involved the dealers cutting and replacing original ground wires. My 01 had the ground cut and obviously a new ground cable installed before I bought it at 125k. The dealer just left the original wire in the harness after it was cut. Im gonna have to look and see if the new X has this as well. Not sure what fords reason was for doing this? Maybe something that was done at the time they did the recall on the brake light switch wiring on the master cylinder? Anyone know more about that?

 

[410Fortune]

sure the brake switch recall was because some genius decided to put a brake pressure switch on the end of the master cylinder for the cruise control. Basically you press the brakes, the cruise control shuts off. However the switch under the hood had battery power going to it all the time and brake fluid is flammable, so any leakage and your truck could burn up.
So the Ford recall was to add some fuses to the power circuit on that switch

Aftermarket battery cable repairs is usually when the battery cable issues begin to get worse!

Good looking cables is one thing, a good solid clean connection is another, any cable that uses a set screw and rubber boot is suspect when placed under the hood environment where they are exposed to moisture, heat and the elements., I would at least give it a good look over
There are not many ways your truck can lose all power intermittently, usually this is a problem with the battery cables on these trucks.

 

[blakshukvw]

I’ve checked both connections where the new harnesses attach to the old wires. No corrosion. I’ve removed those wires and reinstalled and tightened the set screws.
Has anyone else seen these style terminals as I’ve described?
My guess is this was an issue before and someone replaced the terminals with these thinking the original terminals were the issue. Obviously not. I have faith that these terminal connections are good. I’ve looked over and physically checked them numerous times.

 

[blakshukvw]

The issue seems to only happen in the summer heat after the trucks hot. I’m not convinced it’s not a wire or connection that’s compromised just enough that when it gets hot the resistance goes up and causes the sudden power loss.

 

[fast_dave]

@blakshukvw

I've read your entire thread.

The stuff going on within the cabin - i.e. the ABS light activating, the Speedo Needle swinging, sometimes having no interior lights, are just crazy.

You might have more than one issue...

So I dunno if this is going to help, but as far as the running when cold and not hot part of the issue, I'm going to throw this thought out there anyway since it sounds like you've hit the brick wall, and the "test" for this will cost under $20.

I don't know how old your fuel pump is, nor do I know the last time you changed your fuel filter.

A possibility is that during the summer temps when the ambient temperature is high (and thus the gas in your tank is hot) perhaps your fuel pump is overheating due to trying to push fuel through a pretty clogged fuel filter...

So, disconnect the old fuel filter, turn it tank side down into a glass jar, and see what comes out, let us know - heck take a picture!

As far as the other gremlins going on - I dunno...

HTH -