No start

[MTX65]

2012 Ford Expedition 98,000 miles. 5.4L

Wife was driving home the other day when the instrument cluster went haywire. Check engine light, service advancetrac. (Abs and traction control light) no reading for oil life, no reading for mileage, antitheft light flashing. Rpm’s and Spedo went dead. Car died off on her. Towed home and sat for 4 days (I was out of town thinking maybe alternator battery)

Get home and car cranks over. Runs for about 5 minutes and all the same problems happen again, car shuts off and never starts back up. Car in the on position battery voltage is good (can’t load test it) windows, AC, lights, and seats all operational. Vehicle makes not signs of an attempt to crank. No clicks from in the cab or engine compartment either. Read codes. There were a bunch of them that I should’ve written down. I cleared them to see what was active Only consistent was U1055.
I receive a "device unable to communicate with the control unit" for the following

PCM
Abs
RCM
IC
APIM
Dsp
Gpsm
RCU
RETM
TCCM
SDARS
And VDM

Checked fuses and obvious ground wires as well as snug connections to the fuse box and battery.
Spoke to a mechanic on a website that concluded he believed it was the instrument cluster. Shipped off for repairs. Just got a call from them advising their in house testing is showing the unit operational.

ABS module repaired last year. All original keys. No new repairs or noted problems prior to this happening.

 

[Fasttimes]

Checked PCM connections are clean / secure?

 

[MTX65]

Checked pins, connections, and ground. All appear good.

 

[Trainmaster]

Try jumping the battery with a known good one. The failure describe sounds like low voltage. Is the belt still there? Either the battery is bad due to a failed alternator or bad cell or you have a loose wire.

The starting circuit on these trucks is very basic. If it's not cranking, there's not much that can be wrong: Low voltage, deteriorated wiring or a failed ignition switch. There's a relay and neutral interlock too, but they wouldn't affect the truck's running.

 

[MTX65]

When the truck shut off, my wife jumped it to get it started. Started right up until they removed the cables. Immediately died when cables removed. (That’s why initial thought was alternator) few days after initial problem it cranked over no problem for a few minutes before dying off. Battery test was good voltage wise. I don’t have a load tester but I figured after a few days battery voltage being good and cranking over temporarily, alternator would be eliminated no? (Correct me if I’m wrong) I’m starting to lean PCM due to circumstances. I’m just trying to avoid dealership prices if there’s anything else I can self diagnose/fix.

 

[BigOleFordFan]

I had some similar issues with my 11 EL Limited.... it died on me one day and was throwing a bunch of no-comm codes too, along with the PATS flashing padlock and not starting, so after 3 months & $3K worth of diagnostics and replacing the ignition switch, both keys, several wiring harnesses, the HALO sensor, and some other stuff, the 3rd ford dealer I took it to finally solved it....it was the "run/start relay" that was fried....

Thankfully, all is well now

 

[99WhiteC5Coupe]

Your problem sure sounds like a bad battery with a defective cell and/or loose or corroded terminals and/or cable connectors.

 

[Yupster Dog]

Second what @99WhiteC5Coupe said.


You can not diagnose anything electrical until you know it has and is getting the correct voltage.
Start with your battery Go get it tested properly, any Auto parts stores do it for free.

Once you know that you have a good battery
do a Voltage Drop Test to make sure all your connections and cables are good.

Only then can you start to diagnose. Unless you like running in circles

 

[Snuffy]

Check for a loose positive battery cable around the post due to corrosion. It’s a known Ford problem that does NOT require replacing the entire wire assy.

Basically the positive cable no longer has full contact w the battery post and nothing works. It if happens while driving, or if it’s loose and making intermittent contact as you drive it might do the same thing as you’re experiencing. It’s a fairly easy DIY repair.

(https://static.nhtsa.gov/odi/tsbs/2019/MC-10164497-0001.pdf)

 

[MTX65]

I had some similar issues with my 11 EL Limited.... it died on me one day and was throwing a bunch of no-comm codes too, along with the PATS flashing padlock and not starting, so after 3 months & $3K worth of diagnostics and replacing the ignition switch, both keys, several wiring harnesses, the HALO sensor, and some other stuff, the 3rd ford dealer I took it to finally solved it....it was the "run/start relay" that was fried....

Thankfully, all is well now

I checked the run/start relay via multimeter. Shows it’s operating normal. I’m seriously at a loss.

 

[99WhiteC5Coupe]

I checked the run/start relay via multimeter. Shows it’s operating normal. I’m seriously at a loss.

Have you cleaned the battery cable connectors with a battery brush tool and switched to a known good battery?

 

[MTX65]

Second what @99WhiteC5Coupe said.


You can not diagnose anything electrical until you know it has and is getting the correct voltage.
Start with your battery Go get it tested properly, any Auto parts stores do it for free.

Once you know that you have a good battery
do a Voltage Drop Test to make sure all your connections and cables are good.

Only then can you start to diagnose. Unless you like running in circles

Had the battery checked (voltage and load tested) and it all came back normal. I’ll have to look into drop testing.

 

[MTX65]

Have you cleaned the battery cable connectors with a battery brush tool and switched to a known good battery?

Connectors and posts were cleaned thoroughly. Haven’t switched to a known good battery but I did have it tested and it came back fine. Still a chance that a new battery could do the trick?

 

[Yupster Dog]

Check ground connections.
A lifted ground can cause many systems to mess up at the same time like that.

 

[MTX65]

Check ground connections.
A lifted ground can cause many systems to mess up at the same time like that.

I checked all the grounds in the engine compartment. Haven’t checked the ones in the cab yet. Got a new battery. The other day the truck would start right up if I skipped the on position. Just put the key in and turn all the way and it would crank. While running I would get various random codes or no codes at all. (Abs module codes, IC codes, RCM codes) but they were never consistent and would change. Fast forward to today I put a new battery in it and made another attempt. Truck wouldn’t start. I initially tried starting it as usual (on position let the dash cycle and then start) unsuccessfully, then tried to trick it by skipping the on position again and even that didn’t work this time. (I’m assuming because by making the first attempt the truck is storing whatever information it needs to keep it from starting after shutting off.)

 

[Yupster Dog]

(I’m assuming because

Found the problem. you are running in circles instead of actual diagnostics to rule out and move forward.

Nobody can help you from across the internet on your assumptions.

Start over with a "Voltage Drop Test" of all the battery cables (positive and negative)
Check the ground coming off the PCM And other grounds under dash.

You need to finish a diagnostic to rule it out.

 

[BigOleFordFan]

Well it seems as though I spoke too soon about my issue being resolved, because it began all over again on 5/9... so back to the dealer again on Monday, and will wait to see what they say this time...

And yes, I have tried all the suggestions already mentioned in this thread, so I'm back at square 1 as they say...

I am instructing the dealer to just FIX it, either by repairing/replacing/disabling/bypassing or removing whatever components that will correct the issues & give me a fully functional vehicle that I don't have to constantly wonder whether it's gonna start or not when I need to go somewhere....

Thankfully, I have other vehicles to drive in the meantime, but I love my Expy & wanna get it back on the road full time, like, now

 

[BigOleFordFan]

Well, now the dealer says they found 3 additional fried relays, and stated that those 3 & the 1st one they found are directly in the circuit path and part of the PATS wiring, so that when any of them fail, it interrupts the power flow to the PCM, which in turn kills the start up sequence and then triggers the flashing padlock... And that the flashing padlock is the only way for the system to indicate a fault anywhere in that circuit, and that it is not actually an issue with the anti-theft system itself...

Going to pick it up later today, with fingers crossed

They also stated that the next phase would be to start pulling/checking/replacing wiring harnesses and the PCM itself, which will require ALOT of labor & additional diagnostics....so in other words: mucho deniro

 

[MTX65]

Well, now the dealer says they found 3 additional fried relays, and stated that those 3 & the 1st one they found are directly in the circuit path and part of the PATS wiring, so that when any of them fail, it interrupts the power flow to the PCM, which in turn kills the start up sequence and then triggers the flashing padlock... And that the flashing padlock is the only way for the system to indicate a fault anywhere in that circuit, and that it is not actually an issue with the anti-theft system itself...

Going to pick it up later today, with fingers crossed

They also stated that the next phase would be to start pulling/checking/replacing wiring harnesses and the PCM itself, which will require ALOT of labor & additional diagnostics....so in other words: mucho deniro

Oof fingers crossed for you. I finally took mine to a dealership after trying myself and even hiring a mobile mechanic/electrician service who wouldn’t even charge me because he couldn’t find any problems. Dealership said it had a bad abs module. “At the time no other codes” but the module was on an all stop no sales so they couldn’t get one. I found a new one from a dealership 30 minutes away, went and got it and installed it today. Now waiting for them to program it. Asked them about it causing the pats light and a no start and got a beat around the bush non answer followed by a “we will see after we program it now” when they called they told be essentially “abs module, can’t order it, come get it by the end of the week. Miraculously I found 4 new ones within an hour AT FORD DEALERSHIPS. They slipped up today admitting there were other codes for the CAN BUS in addition to the abs module while I was there. Sounds like they were just trying to get rid of it to me. The Tech told me he got it started by wiggling the key in the ignition (I wonder for how long because I read that could occur with a bad ignition cylinder)

 

[BigOleFordFan]

The Tech told me he got it started by wiggling the key in the ignition (I wonder for how long because I read that could occur with a bad ignition cylinder

The 1st dealer I took mine to also mentioned the wiggly key thing, so they replaced the cylinder and a "HALO" sensor to fix that part of my problems...

I picked it up this morning & all seems ok, at least for now.....