Howdy...so I successfully replaced glow plug harnesses both sides on the '02, now am experiencing a new adventure !!

As I was driving to work the other day, the radio light started flickering. No other issues noted...being a firefighter, 24 hrs later left the station after truck warmed up and the kids noticed that the radio light was not on at all. After driving a bit and making a stop, noticed that my tow gauges were not functioning, and the ABS light came on. Was just about to pull into the bank drive-thru and the truck died...no dash functions or electric functions (locks, windows etc)

After a few minutes of calling friends to come help out, got the truck started again and headed down the road to a nearby parts store. After a couple of minutes the truck died again so pulled into a left-turn lane. Fortunately some on-duty brothers helped me push the truck out of the road and into the PD parking lot. After some looking, found that the battery on the drivers side was low (passenger checked out ok). First thought was possible alternator failure (it was still the stock one) so removed it and lo and behold it had gone out. Got a new one, and took the battery to get charged...battery ended up being toast as well. So after a new alternator and battery, truck was up and running with no more weird events until I got home and the dash battery light came on.

After some looking and a test of the new alternator, found that my buddies had forgotten to attach the extra positive lead to the passenger battery. Hooked that up, and no more problems.

....until this morning. On the way to work, radio light started flickering, followed by the dash gauges dimming and going out, followed by the ABS light coming on, followed by all dash lights dimming and going out, followed by failure of dash function, followed by truck dying with no electrical functions. Pulled over and after a few minutes got it started again, but died again...fortunately at a better spot so I could get it off the road.

Any thoughts on what might be going on ? I am at work, will work on the truck tomorrow...thinking maybe the passenger side battery now went out since it wasn't hooked up the other day on the drive home ? NAPA said to bring the truck by with all hooked up so they can run some more tests with everything hooked up. Buddy of mine said to check the FICM, but I didn't think we 7.3 clacker club members had one of those ?

Thank y'all for the help, have a great day !!

 

you won't expect this question - has it been raining?

and does it have the original windshield?

what would that have to do with an electrical gremlin? the windshield seal can fail in such a way that it leaks inside the driver side cab pillar, allowing a little water to drip down on to the PCM (just left of the emergency brake).

a little moisture in there can cause all kinds of random excitement.

for me, this included the radio turning itself on and off, the truck shifting in and out of Overdrive, and the truck shutting itself off while driving down the road - but then being easy-peasy to start again.

 

oh and once I had the windshield and seal replaced, I did not have to do anything to the PCM aside from running the heater for a while. at least, until four months later, when my truck got hit by lightning...

 

Jack, it does not have the original windshield, and it has been raining cats and dogs off and on...hasn't rained in about a week or so.

 

The 02 and later models have a junction block on the left fender just in front of and below the master cylinder. It has two heavy cables going into a plastic cover. They are mounted to a stud underneath. This junction has been known to corrode badly and cause loss of battery voltage. Check there

 

Also, I was just under my truck and saw how green the transmission ground strap was and how less-than-clean the two connection points were - there are a few more of these near the batteries. not likely your problem; AllaboutMPG has a solid idea for you.

but it wouldn't be hard to check the PCM area for moisture

 

Keep an open mind. Don't always trust parts because they are new. Back when I still shopped at autozoo, I had a rebuilt alternator from them that wouldn't put out full voltage as soon as it was installed. Had to argue with them about it because their machine showed it was good. Hooked volt meter to running truck and showed them it wasn't acceptable.

 

I actually took the new alternator back the other day for a bench test, it was performing as it should. Took it back 'cuz of the history you speak of....

 

For what it's worth, best practice is to replace both batteries. The weaker one will drag down the stronger when set up in parallel like that.

In addition to great tips above try swapping the fan and PCM relays under the dash. Good time to inspect for water intrusion too.

 

Well, this one left me laughing.....a lot.....

So I loaded up a poop ton of tools just in case, and headed back down to the truck after getting off work and going home this morning.

Based on the intel from y'all, the first thing I checked was the windshield...see picture below....



I was thinking PCM trouble, but decided to start back from ground zero. Started the truck, and within a couple of minutes the radio started flashing again. Checked the alternator, and it was putting out what was needed. Turned the truck off, disconnected the batteries and tested them. The passenger side was good, but the driver's side (the one that got replaced the other day) was down to 10v...needless to say this caused a serious 'wth'. After taking a deep breath, I was double-checking the alternator connections to the battery on the passenger side, when I did a double-take and noticed that the cross-cable for the batteries was not connected !!! So when my well-intended buddies connected everything back up for me they forgot that connection as well !!

Needless to say, and obviously...the driver-side battery was trying run solo and eventually fire the 'all stop' warning shot.....

After getting everything connected back up the right way, the truck fired right up and ran like a champ for about 2 hrs of errands. Took it by NAPA and everything checked out ok.

So, lesson learned...even the best-intended help (even if they are fellow and former 7.3 owners) can miss stuff, so God-love-'em, double and triple-check their work !!!

Will be following up with Safelite to see if they will replace the seal gasket on the windshield, they already had to do it about 2 yrs or so ago.....

Thank y'all for the help...have a safe 4th of July !!!

P.S. On another good note, no more check engine light after replacement of both glow plug harnesses from the original problem.....

 

Best kind of fix.... easy and free

 

That'll buff out...

 

Even running off of one good battery you shouldn't have had issues once the engine started. The two batteries are used for cranking the larger diesel engine over after that the alternator should handle all the load and supply a little extra to charge the batteries back up. Did the guys at Napa disconnect each battery and load test them separately?

 

Yes sir, they did...