Keyfob range very short. Not battery issue. BCM?

[dogiebitt]

Has anyone experienced this? I've narrowed it down to probably a BCM issue.

Symptoms:

• Cannot lock or unlock car, open trunk, or activate the alarm using the keyfob when more than 10 feet away and in direct line of sight of the front end of the car.
• If the key is in my pocket and my body is between it and my car, the button's don't work. I have to take it out of my pocket and hold it out towards the car (within 10 feet). If I am at the back side of the car, it won't work. I have to walk around to the drivers side for the buttons to work.
• Rarely, car will ping "key not found" while I am inside the car with the key in my pocket. Other error I've seen after turning off the car "restart now, or key is needed".

Troubleshooting: I have swapped keyfob batteries. I have switched to the second keyfob with new batteries (that was never used before, just sat in drawer since new). I just got a new battery for the car, voltage reads perfect (14v) all the time.

Anyone have any ideas?

Does dealer need to program the BCM during a replacement?
Car is a 2015 with 72k miles. So out of warranty.

Sponsored

 

[dogiebitt]

Bump?

 

[Chef jpd]

Put the fob under your chin and hit the button.
No joke............

 

[dogiebitt]

Put the fob under your chin and hit the button.
No joke............

Yep. I’ve heard of this, and tried it. Nothing changed.

 

[Mike Pfeifer]

This sounds like an issue with a poor connection to a receiving antenna. I’m not sure where the antenna is located on the mustang, maybe someone has an idea on that. Some cars have it built in to the glass near the rear heating grid. I have had a couple that had some window tint installed that effectively shorted the traces in the glass and caused the symptoms you are describing. I have also had a damaged coax cable cause this.

 

[dogiebitt]

This sounds like an issue with a poor connection to a receiving antenna. I’m not sure where the antenna is located on the mustang, maybe someone has an idea on that. Some cars have it built in to the glass near the rear heating grid. I have had a couple that had some window tint installed that effectively shorted the traces in the glass and caused the symptoms you are describing. I have also had a damaged coax cable cause this.

I think it's all contained in the BCM. Anyone have any insight to this?

 

[ice445]

I think it's all contained in the BCM. Anyone have any insight to this?

If I remember correctly the car tries to read the key from somewhere in the center console, under the cupholders. Centrally located so the car can "fence" the key and know when it's left the vehicle I guess. But I could be remembering a different model. There's a little slot under the cupholders where you can physically place the key. Supposedly when you use it resets some things, so it may be worth a try.

Alternatively you could have a lot of radio interference around where the car is being parked. Is this range issue consistent everywhere you go?

 

[Skye]

If I remember correctly the car tries to read the key from somewhere in the center console, under the cupholders. Centrally located so the car can "fence" the key and know when it's left the vehicle I guess. But I could be remembering a different model. There's a little slot under the cupholders where you can physically place the key. Supposedly when you use it resets some things, so it may be worth a try.

Alternatively you could have a lot of radio interference around where the car is being parked. Is this range issue consistent everywhere you go?

The current Mustang Owner's Manual references "My Key" , a way to program personalized features into the existing fob. Page 64. Yes. It references resting the fob there. Maybe aim for this area or see if things improve? Maybe simply putting it there and starting the car?

Yes also to the radio interference.

"The typical operating range for your transmitter is approximately 33 ft (10 m). Vehicles with the remote start feature will have a greater range.

One of the following could cause a decrease in operating range:

• Weather conditions.
• Nearby radio towers.
• Structures around the vehicle.
• Other vehicles parked next to your vehicle.
• The radio frequency used by your remote control can also be used by other radio transmitters, for example amateur radios, medical equipment, wireless headphones, wireless remote controls, cell phones, battery chargers and alarm systems. If the frequencies are jammed, you will not be able to use your remote control. You can lock and unlock the doors with the key.

The system may not function if:

• The remote control remains stationary for about a minute.
• The vehicle battery has no charge.
• The remote control battery has no charge.
• There is interference causing issues with the remote control frequencies.
• The remote control is too close to metal objects or electronic devices, for example keys or a cell phone. "

Everyone has Wi-Fi turned on these days. Any number of things use it by default. Population density and cell phones. Construction equipment. The RF spectrum can be crowded.

As @ice445 asked, If you can get the car started, how does the fob work if you park the car in a business park on the weekends or somewhere without a lot of people or companies present? Any better?

 

[dogiebitt]

If I remember correctly the car tries to read the key from somewhere in the center console, under the cupholders. Centrally located so the car can "fence" the key and know when it's left the vehicle I guess. But I could be remembering a different model. There's a little slot under the cupholders where you can physically place the key. Supposedly when you use it resets some things, so it may be worth a try.

Alternatively you could have a lot of radio interference around where the car is being parked. Is this range issue consistent everywhere you go?

I've tried putting the key in that slot under the cup holder. I think that just functions similar to an NFC and allows the car to function even if the battery in the fob is dead.

It did not change the behavior of the fob or car when I am trying to use the fob to lock it from the outside.

As far as location, this happens literally everywhere. Even took a roadtrip away from where I normally drive and it was still happening.

The current Mustang Owner's Manual references "My Key" , a way to program personalized features into the existing fob. Page 64. Yes. It references resting the fob there. Maybe aim for this area or see if things improve? Maybe simply putting it there and starting the car?

Yes also to the radio interference.

"The typical operating range for your transmitter is approximately 33 ft (10 m). Vehicles with the remote start feature will have a greater range.

One of the following could cause a decrease in operating range:

• Weather conditions.
• Nearby radio towers.
• Structures around the vehicle.
• Other vehicles parked next to your vehicle.
• The radio frequency used by your remote control can also be used by other radio transmitters, for example amateur radios, medical equipment, wireless headphones, wireless remote controls, cell phones, battery chargers and alarm systems. If the frequencies are jammed, you will not be able to use your remote control. You can lock and unlock the doors with the key.

The system may not function if:

• The remote control remains stationary for about a minute.
• The vehicle battery has no charge.
• The remote control battery has no charge.
• There is interference causing issues with the remote control frequencies.
• The remote control is too close to metal objects or electronic devices, for example keys or a cell phone. "

Everyone has Wi-Fi turned on these days. Any number of things use it by default. Population density and cell phones. Construction equipment. The RF spectrum can be crowded.

As @ice445 asked, If you can get the car started, how does the fob work if you park the car in a business park on the weekends or somewhere without a lot of people or companies present? Any better?

I've read that the BCM also shuts down non-essential functions (remote lock/unlock being one of them) when the car battery voltage is low. But I just got a new battery, and it's reading 14v which is perfect.

My issue is happening all the time, no matter the circumstances. If anything, it's worse sometimes and I have to actually walk up to the car and use the ribs on the door handle to lock it. I'm ruling out interference, unless it's coming from within the car.

 

[Skye]

But I just got a new battery, and it's reading 14v which is perfect.

https://www.mustang6g.com/forums/threads/bms-reset-no-tools-required.151602/

Just for giggles, have you attempted a BMS reset? After replacing the battery?

Having the car relearn certain aspects of its electronics might help.

Sponsored