Hi All,
I have a 2005 Ex 6.0 240,000mi all stock except for EGR delete, head studs and all that goes with that.
I've had the truck for over a year, no alarm or aftermarket entry, only factory except for stereo and that's through factory harness (stock speakers, etc)

All the sudden the batteries have intermittently started to drain, I found the terminals corroded extensively so I cleaned them and seemed to fix the issue.
The truck sat for two days and would not start, I had to charge the batteries for some length to get the truck started.

Once I got it started, I then charged the batteries and load tested them, both passed ( I even hit them extra hard) then put it all back together.

This is where the problem started, I locked it up and about an hour later i could not get into the truck with the key pad or the key fob.
When pressing lock with key fob and key off, the lights flash for lock and horn will sound when double press, also the panic button works as well, but no door locks.

So far I've checked all the fuses, relays and pinouts for power at VSM, I'm going to look at grounds next.
I've scanned with AE and no codes except EGR, I have also used Alldata for pinouts to test.

Here's what I do know, with the key on everything works as it should, locks, gauge cluster, dome lights, stereo, etc. intermittently if i press the key pad (key off) it will light up on first press then flicker with the next push and then nothing.

Once I put the key in Ignition ( not started) I have to press the lock button on door several times before it starts working, then as long as the key is on or truck is running it works as it always has, I can lock while running with key fob, and key pad.

From what I've tested so far all the constant power circuits have constant power with key off and door locks not working, and as far as I can tell grounds are constant so key on or off should not affect that.
I am obviously missing something like a relay or high resistance from the voltage drop of trying to start with low batteries but I cant find it, and with key on everything works as it should.

any help would be appreciated, thanks.

 

i beleive there is a relay for them under the dash not sure for the diesels but assume its the same door lock wise check the owners manual and it will list what each fuse/relay handles i think one is for looks also this post may help as well https://www.ford-trucks.com/forums/1...ck-relays.html

 

It's been my experience that severely corroded battery terminals means batteries/alternator are bad or going bad.

I know you said you tested but I suspect the corrosion will return, due to battery/charging issues.

Negative terminal corrosion can mean undercharged battery. Positive terminal corrosion can mean over charging.

Check your altetnator too, but I suspect batteries.
How old are they and have the been inadvertently discharged for some reason?

 

You may have had multiple problems..

The door locks not working is a symptom of the "power-saver" relay sticking.
You should also find these other things NOT working at the same time:
* power windows don't work
* RADIO won't turn on
* Digital HVAC system won't turn on

IF you have all these, turn on the headlights.. that will wake up the "power-saver" relay..

Starting the truck may/may NOT un-stick the "power-saver" relay. It may also unstick itself by itself if you just drive it.
I have this issue about twice per year, and just don't worry about it
The headlight trick works for me every time.
"Auto-headlights" (in shade/at night) MAY auto-fix this - I don't recall if it's also effected (hence - MANUALLY turning on the headlights is the fix !)

 

Thanks All,

According to Alldata all the relays for door locks are within the VSM.

The charging system is working correctly

Power windows, Radio, HVAC, all works as it should without any issue at all, Radio stays on until door open, and times out as it should.

So here is what I found;

Initially the batteries were low enough for a no start, I charged the batteries with a processor controlled charger and did not watch it, the charger shows FULL when finished.

It was a few hours before I checked on them and it said full, this is when the door locks would not work.

I first load tested the batteries deciding I will check out the door locks later... both batteries tested good even after a couple back to back load tests. I hit them hard to be sure so I put the battery charger back on to top them off, especially since I would be testing electrical for the door lock issue.

I've tested every single circuit and about to call the VSM having a weak or failing internal relay the issue, but before i get that all together I decided there are worse things than having to use the key to open the door, so I put the dash all back together, besides it still not sitting well with me that everything works fine with key on...

Because I was tired of hearing the Charger, I disconnected it (hint) and after I put everything back together it all was working????

so ok whatever, but it seemed slow to turn over when starting, maybe I had the dome light on, or the ign on the whole time putting the dash together... so back on the charger.

I noticed the charger went right to 16.6 volts, usually only on a shorted cell, or sulfated battery will it do that, so my focus is back on load testing the battery, and I'm done with this truck, pissed off.

I left on charger over night, door locks not working again (figures right, nothing fixes itself) then disconnected both batteries and let sit for a few hours maybe 4.... one failed just barely and the other dropped to 7.6v in about 3 seconds.... so on a hunch I hooked only the better of the two up and everything works... my initial load test was too soon after charging and the only reason I can think as to why they passed the first time..

I replaced both batteries, and had to go through about 8 batteries to find two that had at rest voltage of 12.6 or better, anyway its been together for almost a week and not one issue.

The only time the locks would fail is when the charger was creating an over voltage in the system, maybe the VSM is on its way out, time will tell.

I also found that the upper dash dose not have to completely be removed, so the radio, the 4x4 sw, headlight, etc does not have to be taken apart to get to the VSM, only pulled back and two screws below the radio removed, then the lower part where the trash hook is can be removed, the VSM is against bulkhead just above the trans hump.

the corroded battery terminals were the alternator trying to charge a bad battery..... a battery gauge would of been helpful, I guess that was not important to ford engineers even though my 97 has one and my 2003.

I've been telling people how sensitive the 6.0 is to battery issues, but this goes beyond what I have already known.

Thanks for the replies, I hope this information maybe helps someone else that has an issue like this... prob not as this type of crap only happens to me, but maybe.

 

I'm glad you got it figured out.

I suspected batteries as stated but the fact you load tested them as ok, threw me for a loop.

With the diesels....anytime you have to resort to a battery charger you need to be saving up for new batteries.

I sometimes wonder if the recreational combonation deep cycle/ starting batteries wouldn't be a better battery for diesels. They can take more discharge and bounce back.

 

I had Deka AGM 31 series in one of my trucks. According to Deka they were starting and deep cycle, since there were 4 of them I did not have a starting issue.... I was not impressed with longevity especially as to the cost factor.. even had a digital percent gauge and never dropped them below 60% charge state(40% discharge) before kicking generator in, even though Deka stated I could pull them down to 40% charge and stll get full life cycles out of them... they lasted a little over a year and thats with a 12 step Noco 40amp (10A per battery) charger, and I rotated them twice..

I could have bought cheap batteries 3 times and gotten min of 3 yrs out of them for the same cost.... IDK

I do agree with many that the heat and vibration is whats killing a lot of batteries in the diesels, especially with majority of plates are only crimped, but the deka ones I had supposedly were all welded or soldered (can't remember how they advertised it) but just like Interstate claims Nascar worthiness , I will never buy another Interstate battery ever. Being a mechanic for over 23yrs and replaced a couple batteries in that time, I've had more Interstate batteries fail prematurely than any other battery, even ones I did not install. I will be more inclined to give the AGM Deka's another go before Interstate.

But since I can get them all over the country, at any time of the day or night, I get johnson control batteries from walmart (prob only thing I buy from there), just make sure to test the sitting voltage before buying.

why are the batteries still under the hood anyway? not only bad for the battery, but its safer to have the battery somewhere in back....