Intermittent electrical issues

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

LIthradus

Member
Joined
Mar 29, 2024
Posts
5
Reaction score
4
Location
Canada
I have a 2005 Expedition EB that has developed a few issues possibly related to boosting another vehicle, at least there were no issues prior to that though they could be completely unrelated.

First I did try to search the forum but the search returned an error so I've decided to post instead.

Here are the issues:

1. Power door locks usually don't work, either from the door switches, the key fob or the access code on the drivers door. However they will work once the engine has been running for 10-15 seconds.
- When using the fob the puddle lights activate so I know the truck got the signal from the fob and it's not a dead key fob battery
- Battery voltage doesn't seem to have any effect on the issue
- If I unhook the both battery cables and short the negative to the positive to clear any memory from the modules, the issue goes away for a few days to a week.

2. Fuel gauge started showing lower than expected then went empty. Restarting the truck repeated the cycle for a few days, then it stopped working entirely. Once, out of the blue it worked for a day then quit again. This is probably unrelated to any other issue and is more than likely a fuel level sender issue. I'm only including it because it started at the same time and to be thorough.

3. When I turn off the vehicle sometimes the automatic headlights will click on, then off, then on, then off again.

4. The drivers seat easy entry system where the seat goes back when removing the key sometimes doesn't activate and I have reinsert the key and remove it a second time.


The alternator is putting out good voltage, the battery has been replaced recently and holds a charge well. The back wiper motor works perfectly and isn't drawing excess power trying to park.

Issues 3 and 4 make me think there is a problem with the ignition switch, but when issue 1 is also considered it makes me think there is something wrong with the security module. Though why a full reset resolves those issues has me at a total loss.

Where should I start? These are mostly just inconveniences I can live with so I don't want to throw a lot of money into getting it diagnosed, but if there are any easy fixes or ideas to try I would love to hear them.

Thanks
 

whtbronco

Full Access Members
Joined
Nov 13, 2021
Posts
512
Reaction score
224
Location
Winchester, VA
The best place to start I think is to get it scanned. I can't think of any other way to start troubleshooting this. Codes will give you some direction more than likely. Electrical issues can be time consuming to find.

I've never heard of connecting the ground lead to the positive battery terminal, maybe it's just something I have heard of though. I wouldn't do it.
 
OP
OP
L

LIthradus

Member
Joined
Mar 29, 2024
Posts
5
Reaction score
4
Location
Canada
You disconnect both cables from the battery entirely then connect the cables together for a few minutes, it discharges the any capacitors that may be holding a charge and clears the memory. It's a common enough thing to do, it forces a relearn on the modules. A pita to relearn the idle and shift points but it can fix a lot of stupid issues, its truely "turning it off and back on again", a hard reset. People commonly do it for transmission sifting issues. The same way anyone who works with high voltage caps in outdoor AC for example makes sure a capacitor is safe to handle, they dead short the terminals. Unfortunately since that didn't resolve the issue long term I believe you're right about actually diagnosing the issue, I was hoping maybe someone has a similar issue that had some stupidly simple fix. I suspect that since the locks all work when the engine is running and the alternator is putting out good voltage it may be a ground issue with the security module. There's not enough power at 12.4 volts to overcome a bad ground but at 14+ while running it works.
 

whtbronco

Full Access Members
Joined
Nov 13, 2021
Posts
512
Reaction score
224
Location
Winchester, VA
Ahh yes, I misunderstood what you were doing with the battery leads. Just connecting the wires pos and neg to together I understand. Connecting the ground lead to the pos battery post though didn't make sense to me.

Now that you mention the grounds, that I often seem to forget about, that would be a good place to look. This thread has some info on ground locations and methods of testing them that might help.
 
OP
OP
L

LIthradus

Member
Joined
Mar 29, 2024
Posts
5
Reaction score
4
Location
Canada
Thank you! That thread has a wealth of information, I'll have to go through it after work.
In my original post I mentioned voltage had no effect on the issue but I found this was an incorrect assumption on my part. I put a trickle charger on and watched the voltage with a multimeter at the battery. Below 13.16v the door locks worked very inconsistently. Above 13.2v it was perfect. While I was at the battery I removed the positive terminal and cleaned up the 2 copper lugs that connect to the post and sand papered the positive terminal. As usual the issue has gone away after the battery has been disconnected so I'll know if that has helped at all in a few days to a week or two. Then I'll get into checking grounds. Now that I know the key is voltage I'll definitely be focusing on a power\ground issue.
 

tekrsq

Full Access Members
Joined
Jun 14, 2017
Posts
144
Reaction score
39
Location
Chesterfield, Va
About 2 yrs ago, I had an electrical gremlin on my 1st gen that I looked for almost 3 months. I weas convinced the GEM was bad, and was even confirmed by a Firestone station. However, the Firestone would not replace the GEM because it had to be programmed by the dealer. When I took my truck to the dealer, they of course had to do their own diagnostics. The dealer discovered I had a lose ground wire in the passenger side kick panel...not a bad GEM. They fixed the ground issue, and I've not had any gremlins since.
 

Speed 330

Well-Known Member
Joined
Dec 10, 2021
Posts
70
Reaction score
21
Location
Fl
The best place to start I think is to get it scanned. I can't think of any other way to start troubleshooting this. Codes will give you some direction more than likely. Electrical issues can be time consuming to find.

I've never heard of connecting the ground lead to the positive battery terminal, maybe it's just something I have heard of though. I wouldn't do it.
Take the negative cable off the battery then take a jumper wire from the positive to the negative cable wait 15 minutes that clears every diode in the system then you can connect it back up that's the proper way to clear a Ford
 
OP
OP
L

LIthradus

Member
Joined
Mar 29, 2024
Posts
5
Reaction score
4
Location
Canada
I might be cursing myself here but it's been over two weeks since I cleaned up the copper lugs at the positive battery terminal and the issue that uas been plaguing me for a couple years hasn't returned.
 

whtbronco

Full Access Members
Joined
Nov 13, 2021
Posts
512
Reaction score
224
Location
Winchester, VA
Poor battery connections can cause some strange issues on these computer controlled vehicles. I hope you found the culprit.
 
Top