Trouble with SKS Smart Key Fob Detection

[jansjone]

Hello,

I have a 2005 Prius that started having fob issues several months ago. The trouble started very slowly, and has managed to get progressively worse. The trouble is that when you walk up to the car, it doesn't detect the fob. My wife and I have each had the same issue with our respective fobs. It originally would happen around 1 in every 10 times, but now it happens almost every time we walk up to the car.

I at first thought it may be an issue with the batteries in the fobs, so I replaced the batteries in both. The problem continued as if nothing had changed.

Also, it's not only an issue with the doors. If the doors are already unlocked (e.g. car in the garage), then the car doesn't want to start when you first get in (it does't see the key). The solution in every case seems to be to press the lock or unlock button on the fob a couple times. Generally, the first press of the unlock button does nothing, but after hitting it a couple times, it seems to "wake up" the listening device, and then the car behaves normally, allowing you to lock, unlock, power on/off, etc. via the keyless methods.

Has anyone seen this behavior before? Any ideas on how to solve it, short of taking the Prius in to the dealer?

Thanks,
Janssen

[ceric]

Janssen:

Based on your description, my guess is one of the SKS sensors in the Prius (for detecting SKS transponder) is going out (or is out).
My guess is based on
- both your fobs (transponders) have problem - therefore, not the transponder, should be something in the car.
- you have problem entering and starting the car (sensors play a role in both cases to determine the location of the transponder)
(of course, it could be the SKS processing unit also)

Sine yours is 2005 (like mine), you should bring the vehicle to dealer for them to do a thorough check since your warranty is going out.

[TonyPSchaefer]

Yeah, I'm agreeing with ceric. For me, the telltale comment was that clicking the button on the fob remedies the situation.

Keeping in mind that the Prius is responsible for detecting the SKS, you can understand that if the detector's going out, it simply will not detect it.
On the other hand, pressing the button on the fob sort of "forces" a recognition.

[efusco]

Would bet on the SKS ECU from the description rather than the sensors...if it were a sensor then it should only be a problem with one door or only with the start up I would think. But you have at least two sensors involved (driver's door and internal oscillator)..you didn't say if the problem also occurs with the passenger door and hatch sensor..but I'm going to guess it does.

Yea, it could be the fobs are both bad, but good ol' Occam's Razor would dictate a single source as the most likely cause and thus my assumption of the SKS ECU.

regardless of my pontification on the subject this is a dealer thing.

[pviebey]

FWIW, I had 2 'keys' in my pocket yesterday. One went to a Python car alarm, plus my Prius. Prius didn't 'recognize' the key until I took it away from the Python remote.

The Python remote is bi-directional (monitors alarm), and I'd guess was 'stepping' on the RFID.

So, FWIW, just offering the thought to make sure there's no potential conflicting transmitters 'in the way', on the same keychain, whatever.

Third (and least expensive) solution <grin>...at least worth checking.

[jansjone]

Thanks for all the info. Yes, the problem does occur at the hatch, both doors, and in the car. As both fobs started showing the symptoms at the same time, I'm going to guess it's not both fobs going bad simultaneously. The thing that seemed the most peculiar to me is that pressing the unlock button makes the SKS wake up.

As for other transmitters, both my wife and I carry cell phones, which have 802.11, Bluetooth, and GPRS, which are generally within an inch or two of the respective fob, but i wouldn't think that those would cause the trouble. I'll try and experiment tomorrow to see if not having a phone near the fob changes things at all.

It's hard to troubleshoot because it's intermittent. Also, in general, once it wakes up, it seems to be fine for the next several hours.

But yes, my warranty is near expiration, so I'll probably take it to the dealer anyway. I guess I should unhook my EV wire from the high beam switch. I don't know what the dealers think of such things, or if that would cause any problem from their perspective.

Janssen

[efusco]

With the extensive electronics you carry and the intermittent nature it very well could be interference.

Do experiement with them carefully separated for a few days to see if the problem goes away. I had the impression that this was a very frequent problem that had been getting worse. An ECU failure I would expect to be more complete and less intermittent...interference is a very real possible cause.

Try to take note if this is occuring in any particular location or locations...I know a few people found certain areas of certain parking lots their SKS wouldn't work and we presumed it was from interference of something electrical due to the fact it worked perfectly elsewhere and was reproducible in that one location.

[Frank Hudon]

only time we've had problems with the car recgonizing the fob is when the cell phone is between the fob and the car. Cell's and Prius can be a problem.

[jansjone]

Thanks again for the replies. To clarify a bit on the intermittent part: I'd say I generally only use the car twice a day - driving to work in the morning and driving home from work at night. Around half the time (I never really tracked enough to know exact numbers), when i walk up to the car and grab the handle, nothing happens. I then pull out my keys and click the unlock button, which also doesn't SEEM to work the first time I click it, but generally does seem to work the second time I click it. Then everything works fine for the rest of the day. So my test window is only twice every 24 hours or so. If it works, then I'd have to wait until the next day to try it. Again, it SEEMS to only have the trouble after several hours of me being away from the car (I haven't seen the issue if I stop at the grocery store on the way home and then return to the car). But again, I'm using the non-scientific "guessing" method, as it's difficult to follow the patterns since it is intermittent. This morning, everything worked fine. I'll continue to monitor, and let you know once I find out more.

As for the cell phone issue: I mentioned this to my wife, and she said noted that we've had these phones for more than a year, but the SKS troubles only showed up in the past six months or so, so it seems odd that the problem has just started showing up at this level.

Though it's definitely not ruled out. Maybe I'll go ahead and call the shop and see if they can provide any words of wisdom.

Thanks again,
Janssen

[richard schumacher]

Try the simple cheap thing first: *one* of you carry your fob for two weeks in a pocket/whatever with no other electronics (and ideally no coins either) in that same pocket/whatever.