S550 Keyless locking not working

[The Latman]

Roger.

When going in for MOT, you and the tech can look at the top. If a Motorcraft, it has a raised date stamp. Not always obvious (or easy to read), because the numbering is not highlighted.

Good Luck.

Thanks

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[KeyLime]

If you have the original battery in the car it's worth replacing soon. It's near end of life and you'll be stranded in the not too distant future.

Maybe you'll get lucky but I doubt a new battery is going to solve the door lock issues. The starter pulls about 300 Amps. If the battery can deliver 300 A it can deliver 0.3 A to pop a door lock. Ditto for keeping some sensors and circuit boards active when the car is turned off. The problem is likely somewhere else, bad sensor, bad switch, loose/corroded wiring, etc.

I you have multimeter try this. It won't fix anything but it'll give you an indication of battery health.

1. Measure the voltage after the car has been sitting for a few hours. A good battery should be in the 12.4 to 12.6 v range (see attached chart).

2. Crank the starter while measuring the battery voltage. This will likely be a two person job. And while cranking hold the gas pedal to the floor. That will prevent the engine from starting but still allow cranking. If the voltage drops below 10 V the battery is getting weak.

3. Start the car. As others have said the voltage with the car running should be 14.5 ish or so. That's the normal output voltage of the alternator and charging system.

 

[The Latman]

I’ll check the battery this evening or tomorrow. I don’t know the age of the battery in the car, a previous post said it might show the date on it.

I don’t think it’s an issue with the sensor or wiring, both stopped working at the same time. I’ve also noted the reverse parking sensor chimes are coming from the dash a lot more than normal.

This evening, after a day of driving, both doors are now locking using the proximity sensor.

It is going into the dealer for a service / MOT in couple of weeks (last of a service plan), there is also a garage that specialises in American muscle through in Edinburgh, so I might speak to him rather than the dealer as I have far more trust in him than the dealer.

 

[The Latman]

OK, thanks for all the feedback. The locks have been behaving themselves since my last message. I did check the battery this morning with my multimeter and it shows 12.1v. which is just over 50% charge ... There isnt a date stamp on the battery, but it does show FoMoCo Dearborn Michigan.

Given I live in Scotland, I reckon this is the original battery.

Generally, how long would I drive to charge it to full from this level (assuming it will charge to full)

I will be embarking on a 300 mile journey on Monday, return leg on Tuesday.

Ill try & get a battery before then (Halfords have one for around £120), failing that I'm sure she'll last another 600 miles.

 

[Skye]

A guideline I've seen referenced several times is an 80% State of Charge, so you're a tick down.

As to how long to drive for topping up, my personal goal is 30 minutes to an hour, but I've never studied or measured it. The alternator is capable of generating 10s of amps of current. With the car started and running, after the Powertrain Control Module allocates alternator output to coil packs, fans, etc., it will serve the rest to charging the battery.

The other half of the equation is the battery itself. Being older, the internals have naturally degraded. They're less accepting of the charge or holding it. We could be seeing a bit of that now, in the 50% state versus 80%. You could drive the first half and see a difference in voltage. You might drive it and see no change at all.

Good on pricing the new battery. If anything, it will establish a known baseline. You'll have a new battery, know when it was made and installed.

 

[The Latman]

A guideline I've seen referenced several times is an 80% State of Charge, so you're a tick down.

As to how long to drive for topping up, my personal goal is 30 minutes to an hour, but I've never studied or measured it. The alternator is capable of generating 10s of amps of current. With the car started and running, after the Powertrain Control Module allocates alternator output to coil packs, fans, etc., it will serve the rest to charging the battery.

The other half of the equation is the battery itself. Being older, the internals have naturally degraded. They're less accepting of the charge or holding it. We could be seeing a bit of that now, in the 50% state versus 80%. You could drive the first half and see a difference in voltage. You might drive it and see no change at all.

Good on pricing the new battery. If anything, it will establish a known baseline. You'll have a new battery, know when it was made and installed.

Thanks for this. Ive been on a few longish runs as of late, not quite half an hour though, but I would expect the battery to be a bit higher in charge now that I'm armed with this information. I can do without replacing the battery financially (it IS January after all), but hey, i own a car so its something thats needed.

Once yesterday, and this morning, the Sync unit didnt start, until I engaged reverse and the camera came on.....so i reckon this battery needs to go.

 

[GTP]

I am still skeptical that this problem (for many of us) is related to the battery charge. So please check in and update your thread periodically. If all remains well, then I might be convinced. Fingers crossed for you!

I forgot - do you have a battery maintainer?

 

[The Latman]

I am still skeptical that this problem (for many of us) is related to the battery charge. So please check in and update your thread periodically. If all remains well, then I might be convinced. Fingers crossed for you!

I forgot - do you have a battery maintainer?

I dont, but my car is my daily so she goes everywhere with me.

Since my update the other day, the locks have been fine, as they were since i got the car in March '23

It might be me, but I just cant see it being a sensor, when both act up at exactly the same time. (I was an IT field engineer for 7 years, and a telecoms equipment field engineer for 14 years, so I like to troubleshoot and look at things logically)

 

[The Latman]

Hey folks, by way of an update:

Locks have behaved ever since they started behaving again.

Ran my multimeter on the battery, 12.3 and I’ve been out today.

Had my son run the multimeter whilst I started the engine, 10.3v, before shooting up to 14.5.

Got a 300+ mile trip tomorrow, back up again on Tuesday. I’ll be interested to see what the meter says both days.

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