PO500 story continues with new twist

[jr1under]

The timing of both of us having the same problem has me thinking they’re sending destroy signals over the cell network lol

Good thing they're too old to have an internet connection to collude over.

As the GEM is inaccessible(to me), I've tried to prove it's not the problem but the randomness of the codes points right back to it. Like most of the others, the P0500 came and went. The only consistency has been a B1323-Door Ajar Warning Lamp circuit failure even though there are none of the symptoms normally associated with that code. I pulled and checked all six door latch assemblies and their door ajar sensors, everything looked and tested ok.

I wonder if the persistent codes are just debris from a GEM crash and, if so, what's causing it? It could be that the GEM itself is damaged or it could be resetting after a voltage drop or it could be something else. As usual, I have more questions than answers.

 

[Billme]

Good thing they're too old to have an internet connection to collude over.

As the GEM is inaccessible(to me), I've tried to prove it's not the problem but the randomness of the codes points right back to it. Like most of the others, the P0500 came and went. The only consistency has been a B1323-Door Ajar Warning Lamp circuit failure even though there are none of the symptoms normally associated with that code. I pulled and checked all six door latch assemblies and their door ajar sensors, everything looked and tested ok.

I wonder if the persistent codes are just debris from a GEM crash and, if so, what's causing it? It could be that the GEM itself is damaged or it could be resetting after a voltage drop or it could be something else. As usual, I have more questions than answers.

I’m testing for a voltage drop when I let it sit for a day next.. my last two codes were low voltage, and of course the P500.. I guess we’ll eventually get it.. I was thinking back when all this started, and it’s when I had my alternator over hauled…I currently have it parked out side for the last month to see if I find any leaks.. So far, none has showed up..

 

[jr1under]

I’m testing for a voltage drop when I let it sit for a day next.. my last two codes were low voltage, and of course the P500.

If mine sits 3-4 days, the battery will fade from 12.5V to as low as 12.2V. Haven't tested it for longer than that but I think that's when the low voltage code shows up along with the always-present door ajar code. And the voltage code persists even when the battery gets back to 12.5V.

Maybe cranking at 12.2V can brown out the GEM and cause it to reset? But even if true, that still circles back to the question of what's draining a less than one year-old battery.

 

[Billme]

If mine sits 3-4 days, the battery will fade from 12.5V to as low as 12.2V. Haven't tested it for longer than that but I think that's when the low voltage code shows up along with the always-present door ajar code. And the voltage code persists even when the battery gets back to 12.5V.

Maybe cranking at 12.2V can brown out the GEM and cause it to reset? But even if true, that still circles back to the question of what's draining a less than one year-old battery.

Wow, we are on the same track, this is nuts.. Clear your codes, then unhook your battery.. Grok said this makes sure the Gem clears its memory…I have the same problem with battery drain all of sudden.. The new switch allowed me to bump the rear wiper motor.. It’s locked up.. The other item is side rear view mirror on the passenger side.. My body to engine ground is not in the original place..I put it in the list to check..
I think you are on to something.. Maybe it’s time to get one of those tic tok tools to find these problems lol

 

[Billme]

Even though it’s cold, my battery was 11.55 hummm
I let it run and the alternator was pumping out 14.5..
Rest state is 12.6, but now I’m unplugging a phone charger that has a led light in it to see if that’s whats doing all this. It’s on all the time. The battery is coming up on 3 yrs..

 

[jr1under]

Even though it’s cold, my battery was 11.55 hummm
I let it run and the alternator was pumping out 14.5..
Rest state is 12.6, but now I’m unplugging a phone charger that has a led light in it to see if that’s whats doing all this. It’s on all the time. The battery is coming up on 3 yrs..

Yeah, hmmm is right, 11.55 is bordering on the starter click zone. There has to be more than a single LED draining it like that.

I did follow grok's advice to the point where it concluded the villain was GEM and the next step was easy - pop off the kick panel to inspect and clean two connectors. And it was easy...to pop off the kick panel. However, there was nothing behind it I'm willing to dig into especially after following your experiences.

Now I'm wondering if the GEM is actually ok but occasionally gets browned out and reset. That could explain the random, flaky codes but otoh I trust the low battery code because the meter confirms it. So what about the persistent door ajar circuit fail? Is it possible for a circuit to be in some sort of fail mode that causes a power leak yet all its components work correctly?

 

[Billme]

Is it possible for a circuit to be in some sort of fail mode that causes a power leak yet all its components work correctly?

I guess it is, I just don’t know..
I found a half a volt pull where the rear wiper was trying to park, all this time, so like you, I pulled fuse 12, and got that out of the way.. I have two more known problems with the power mirrors and the passenger window stuck closed.. Whatever the remaining drain, it’s not much..
Ill check the voltage tomorrow and see where that leads..
I’m now getting solid PO 500, so I’m going to change it and the connector this time.. It’s still in warranty.. If I get another low voltage code, I’m going to change the battery..
Grok is hot and heavy on the VSS connection..
Oh well, it’s keeping me busy hehe
Did you say that you physically looked at the door switch?

 

[jr1under]

The constant P0500...are you getting a CEL with that?

After sitting for 4-5 days and getting down to 11.7V, I decided to ignore the door ajar code and focus on the low voltage, find out what's really causing it. Except that it's 27* and snowing, it went easier than expected. The meter showed about a 0.25A draw so I just started pulling fuses from the inside panel. Turns out circuits 14 and 15 are accounting for 90+% of the drain. What to do about that is the next question.

i pulled out all six door latch assemblies so I could remove the switches for inspection.

 

[Billme]

Turns out circuits 14 and 15 are accounting for 90+% of the drain. What to do about that is the next question.

Those carry multiple circuits as well, I would look at the listings for what might have their own circuit under the hood, and get as many as you can isolated..
No, I still didn’t get a CEL on the P.O. 500 I meant solid as in every time I run a code test it’s there, and by itself many times now.. By pulling #12 under the hood stopped the low voltage for that session.. I haven’t went back yet to check voltage, because it’s too dang cold lol

 

[Billme]

Now that I got my transmission moving again, and shifting good, I can get back on the PO 500 ghost.. Since is more solid but still not tripping the CEL, I’m going to recheck the VSS and change out the connector this time..
I did confirm I do have a windshield leak somewhere, because I left it outside during the storms.. So I got to get that tomorrow with this better weather.. .. So if all this still doesn’t get it. I’m going to get remanufactured Gem..

 

[Billme]

Got my transmission at least where it’s driving..
I’m now just getting the PO500 when I go to crank it only.. I can clear the codes, and it want come back on till I crank it.. I’m going to unhook the starter and clean that up.. It may be a corroded harness, something is allowing low starter voltage messing with the GEM? Who knows, but I’m headed down that rabbit hole now, lol
I’m going to just switch batteries first.. Do the easy stuff first

 

[jr1under]

I’m now just getting the PO500 when I go to crank it only.. I can clear the codes, and it want come back on till I crank it..

My interpretation of what grok and the OBD SysOp manual say: Unless the truck is moving, the VSS does not output a signal nor does the PCM expect one. So, when you clear codes and crank but remain in Park, where is that P0500 coming from? No clear proof but I still suspect it's a phantom code.

The manual also states for some transmission codes like P0500, "in such case a non-MIL Diagnostic Trouble Code (DTC) will be stored." That explains why the CEL doesn't light.

 

[Billme]

Well, I got the mechanic to put a new connector on the VSS, and no change.. I’m able to drive it… I’m done with this, I’m going to change out the Gem..
Thanks for that info Jr1under..

 

[jr1under]

Mine continues to have a 0.22A drain and Low Voltage code. The draw is split evenly between two circuits but I haven't isolated anything yet. I did pull out the Battery Saver Relay which tested ok for current and resistance. Still don't know if the problem is that there's current on those two circuits or that the GEM isn't blocking it. Or something completely different.

 

[Billme]

Mine continues to have a 0.22A drain and Low Voltage code. The draw is split evenly between two circuits but I haven't isolated anything yet. I did pull out the Battery Saver Relay which tested ok for current and resistance. Still don't know if the problem is that there's current on those two circuits or that the GEM isn't blocking it. Or something completely different.

Beats me, I’m just going to bite the bullet when I pull the dash, every connector will be checked, and the Gem replaced.. I’m convinced it’s the Gem.. I also want to see how if it does, effects the engagement of the Torque converter..
I’m looking forward to what you find..

 

[Billme]

I should have put all my updates on this thread, anyway… My speed test didn’t show a PO 500 this time, but the shake was there.. So I pulled over and something told me to open the fuel cap.. It had a lot of vacuum on it, and the engine idle was upset briefly.. So I went back to high speed, no quivering shake, even up to eighty.. I’m now keeping and eye on this, so far it’s not doing it again..
After another hard reset and a small trip, I ran another code check, I’ll post it.. Some stuff showed up I’ve never seen before..I think it was at this point I was going to check the power feed from the battery to the Gem via the ignition switch coil to the battery junction box.. The feed to the GEM from there is 103.. The 50 amp fuse was old and the top cover was broken.. I just reseated it making sure the blades were clean.. I noted no quivering in the dash lighting as much, so this was a change.. I also found my fog light fuse connection was not there, so it must be dangling below, so I’m going to pull the whole junction box and check that all out, plus use a bunch of dielectric grease.., then follow the harness to the Gem, via all the firewall connection… Every connection will be cleaned and dielectric grease applied..
Something I accidentally learned on the BlueDriver is if you use the separate clear codes box on the main menu, it will clear the GEM memory without having to unhook your battery..Neat little side note, huh? If you use the clear codes box while in the check codes section, it want to clear the GEM memory..
So right now I’m learning how to disassemble this Junction box lol
Btw, the computer is just now seeing I pulled the fuse on the rear wiper motor months ago..
I wonder where all this is going to lead, probably IFIXIT , or UpFix didn’t really check my Gem in Atlanta, and maybe I got a funky PCM from Flagship 1 .. We will eventually find out..

 

[Billme]

I can’t believe there is not one YouTube video on the battery junction box for Gen1 Expeditions.. I have the original manual, and not one word on it as well..I asked Grok, and it couldn’t find any thing on it.. Interesting..

 

[jr1under]

I can’t believe there is not one YouTube video on the battery junction box for Gen1 Expeditions.. I have the original manual, and not one word on it as well..I asked Grok, and it couldn’t find any thing on it.. Interesting..

Are you talking about this box?

 

[Billme]

Are you talking about this box?

Yes, I’m trying to figure out how to deal with it taking it out without destroying anything lol
Under your hood looks great too! Good job!