Interference

[333mrg Lurker Find all posts View Profile Close 333mrg]

Hi PP,

New to the forum and couldn’t find anything related to this topic in other forums, so hoping someone can point me in the right direction to resolve this problem.

I’ve recently purchased a 2021 VX Prado and loving it. I’ve installed a dual battery (lithium) under bonnet with a Redarc 1225 installed on a Kaon tray behind the grill, and a Kings drawer fridge in the rear cargo area. All pretty standard.

The problem I have is when I try and unlock the door either by the key fob or by holding the handle, it doesn't work on either the drivers side or passenger side of the car. The only way I can open or close the door is from the tailgate. Same when starting the car, I basically have to hold the key fob in my hand when pressing the start button, otherwise the display tells me there’s no key.

I’ve disconnected the wiring at the aux battery servicing the rear cargo area and everything returns to normal and everything works again.

I used 8b&s (twin) run in split conduit along the chassis to the rear and discovered the problem, so I pulled that cabling out and then ran 6b&s (single), with a separate earth to the chassis at the rear of the car on the second attempt and it made no difference.

Assuming I’m not the only person this has happened to, so any help in solving this problem would be greatly appreciated.

[Piggy Water pistol pilot. Find all posts View Profile Close Piggy]

Sounds like some type of interference or you are upsetting the can bus. . Where have you run the cables to the rear? Plenty of room along the door sides under the interior plastics. Disconnect everything on your new cable to the rear and with just the cable energized see if the issue is there. Add devices till it happens if it's not.

[GeeWhizz Senior Member Find all posts View Profile Close GeeWhizz]

You don't mention the state of your key fob's battery. I'd start my search for the problem by replacing the battery - your symptoms are typical of an exhausted fob battery. The battery in my fob only lasts 6-8 months.

[333mrg Lurker Find all posts View Profile Close 333mrg]

Sounds like some type of interference or you are upsetting the can bus. . Where have you run the cables to the rear? Plenty of room along the door sides under the interior plastics. Disconnect everything on your new cable to the rear and with just the cable energized see if the issue is there. Add devices till it happens if it's not.

Hi Piggy, I've run the cable in split conduit under the car along the chasis and up through the gromit in the rear of the car. About to try exactly what you've suggested in regards to disconnecting everything. Will let you know how it goes

[333mrg Lurker Find all posts View Profile Close 333mrg]

You don't mention the state of your key fob's battery. I'd start my search for the problem by replacing the battery - your symptoms are typical of an exhausted fob battery. The battery in my fob only lasts 6-8 months.

Hi GeeWhizz, The cars only a few months old and I've tried both the everyday key fob and spare, with the same issue for both. To rule out this as a possible cause, I'll change the batteries and see if it makes any difference. Thanks for the suggestion.

[catherder Junior Member Find all posts View Profile Close catherder]

The fob receiver unit is located under fridge you installed....
I'd start by seeing if turning the fridge off helps, then remove fridge, then check for wiring damage to the receiver.

[Piggy Water pistol pilot. Find all posts View Profile Close Piggy]

The fob receiver unit is located under fridge you installed....
I'd start by seeing if turning the fridge off helps, then remove fridge, then check for wiring damage to the receiver.

The rear fob receiver is under his draws and fridge, that is the one for the rear door. (Which is working by his description). More than likely the one under the console is being annoyed by the new cable routing. Or some type of interference from his new cabling/ fridge etc as you say.. And yep, disconnecting and adding items one by one should find the culprit.

[333mrg Lurker Find all posts View Profile Close 333mrg]

Thanks for all the suggestions guys. I’m pulling everything apart to try and get a handle on the problem over the weekend, so will provide an update.

Since the post I’ve changed the battery in the key fob to eliminate this, which made no difference. I’ve installed a ferrite choke at the aux battery end after reading an article around EMI and that seems to have helped slightly. The doors lock / unlock maybe 50% of the time now, rather than not at all.

[333mrg Lurker Find all posts View Profile Close 333mrg]

Hi, just an update to let you know that I identified the source of the interference. I’m not sure if you’re allowed to use brand details, so I won’t document that, but it was the 6 way control panel that I’d installed causing the interference. Since I’ve removed the unit and gone to an old school manual switch type panel, no issues.

thanks to everyone for your suggestions along the way.

[catherder Junior Member Find all posts View Profile Close catherder]

I’m not sure if you’re allowed to use brand details,

Sure. People's names can be an issue but you can share company and brand experiences.

[Piggy Water pistol pilot. Find all posts View Profile Close Piggy]

Hi, just an update to let you know that I identified the source of the interference. I’m not sure if you’re allowed to use brand details, so I won’t document that, but it was the 6 way control panel that I’d installed causing the interference. Since I’ve removed the unit and gone to an old school manual switch type panel, no issues.

thanks to everyone for your suggestions along the way.

I'll take a hot guess as a Kings (4wd Adventure store) switch panel. As they have a cheaper style 6 way one.

[ptommo59 Senior Member Find all posts View Profile Close ptommo59]

Different issue but I have found my iTechworld 40A DC-DC charger when operating affects the FM radio sensitivity.

Must be interfering with signals received through the window antenna as It doesn't make any sort of noise just drops the weaker radio station signals in and out when charging.