Key remote matter, do we even need a remote.

[NeddyBear]

On Saturday we went mountain biking for 6 hours and when leaving the car I put the key in my rear pocket, first time I've ever done this with the key and after 6 hours of sitting on it when we returned to the car the remote wouldn't work.
This frightened the crap out of me since we were still 12klms from the highway and a further 78klms from home and I wasn't sure if the key would start the engine because of the remote not working.
Anyway I opened the front door and popped the boot and then tried the ignition and to my surprise she fire straight up so this has me thinking.
When you go to get a spare key and they say you need to have the key programmed is that just the remote their talking about.

I'd been thinking of getting a spare key for under the car just encase I ever lock the key in the boot again and am now thinking all I need is a blank key part and have it cut and fasten that up under the car without the remote.

Is this correct about the spare key blank cut and nothing else is needed or was starting the car without the remote working just pure arse.
The funny thing is after driving the 90klms home the remote was working fine and is still going strong so once again I'm wondering was the remote battery flat and needed charging via the ignition or was it just unhappy from being sat on for so long.

 

[Nut Kracker]

OK....
1) The only reason there is a battery in the remote is,
that we are a lazy society and pushing a button is easier than turning a key in a lock.

2) The battery in the remote has absolutely nothing to do with starting the car.
My remote was flat for 6 months and I ended up with RSI from turning the key in the lock lol.
(I don't think the Holden engineers would leave you stranded in the middle of no where just because the remote's battery went flat).

3) The battery does not get charged from the ignition.
You cant re charge the lithium button battery....Well you can try, but they'll blow up if you do.

4) A key without the fob will not start your car, as the metal ring (key reader) around the ignition needs to come in contact with the little metal knob on the end of the fob.
(Which incidentally, is NOT powered by the remote's battery).
The key reader around the ignition talks to a chip in the fob. This in turn sends data to the BCM. If the BCM correctly reads the fob's codes,
it will send a signal, via the serial data wire to the PCM, confirming it is ok for the PCM to start the engine.
Also, that's one reason why the BCM and the PCM have to be linked together.

 

[mouseno4]

My parents have had their key fob broken for YEARS. Short story shortened the PCB that connects to its internal battery had broken off and soldering it back together only proved temporary.

Years later we finally had the entire fob replaced (key comes in two halves for an Astra key fob) and now works well. Cost $150 but the sheer convenience was well worth the cost.

 

[devilly]

OK....
1) The only reason there is a battery in the remote is,
that we are a lazy society and pushing a button is easier than turning a key in a lock.
ain't that the truth and it makes like so much easier to pop the boot for shopping e.t.c.


owner of car is responsible for the security with it, personal i always put on the steering lock and then the wheel lock with key thingo. then i have a kill switch and also have a gps tracking device.with i installed myself so no-one knows where they are

 

[TI3VOM]

OK....
1) The only reason there is a battery in the remote is,
that we are a lazy society and pushing a button is easier than turning a key in a lock.

2) The battery in the remote has absolutely nothing to do with starting the car.
My remote was flat for 6 months and I ended up with RSI from turning the key in the lock lol.
(I don't think the Holden engineers would leave you stranded in the middle of no where just because the remote's battery went flat).

3) The battery does not get charged from the ignition.
You cant re charge the lithium button battery....Well you can try, but they'll blow up if you do.

4) A key without the fob will not start your car, as the metal ring (key reader) around the ignition needs to come in contact with the little metal knob on the end of the fob.
(Which incidentally, is NOT powered by the remote's battery).
The key reader around the ignition talks to a chip in the fob. This in turn sends data to the BCM. If the BCM correctly reads the fob's codes,
it will send a signal, via the serial data wire to the PCM, confirming it is ok for the PCM to start the engine.
Also, that's one reason why the BCM and the PCM have to be linked together.

I always thought the key had a code that disabled the immobilizer? Or at least that's what I'm sure I've read previously.
If thats the case it's good to know as I have to start my car soon and they key hasen't been used for over a year (thinking the battery might be flat by now).

 

[WHCapriceHBD]

You can't just "cut a key blank" and "put it under the car for an emergency".

People have stated that even if the key battery goes flat, (as yours probably did in your back pocket) the security system uses the small metal tab on the key along with the key shank itself, to pass a current through, by means of contacting the metal ring around the ignition barrel. This energizes the circuit inside the key responsible for talking to the security system.

If you attempt to start these cars with just the plain cut key shank with no other circuitry on the key, the car will not start. As no codes are exchanged. Its freely written online how the security system operates, so maybe sit down with a coffee and have a good half hour read up on whats inside your car, to familiarize yourself with how the system works.

 

[Jxfwsf]

As above, you likely had the buttons pressed in on the remote while sitting on it for so long, if it's an old key this probably flattened the battery which is why it didn't work.

There's 2 ways to disable the security, 1 by pressing the button and unlocking the car (disables it for a short time), 2 putting the key in the ignition and contacting the points.
Think of each as a fail safe, in your case #2 worked. You'll also read of people having to press the button while turning the key when there is an issue with the key contacts on the ignition.

Chances are that by the time you got home the battery was able to recover slightly which is why it worked, but it probably won't last much longer on the remote side.

Some believe the contacts on the key are to charge the battery, not true. It's a long life lithium battery that is not rechargeable, there is very little draw on the battery when the buttons aren't pressed and should last for years.
The bcm also changes the code it uses which is why a spare key that hasn't been used for a long time won't remotely unlock the car but after being put in the ignition and used to start the car will work again (the bcm just updates the key to work again)

 

[goose202]

I know the consensus is that the battery doesn't get charged from the contacts but it seems opposite to my experiences.

My wife's key to my VX rarely gets used, maybe once a month. The remote buttons stop working. Have to use the key in the door. After a 10 minute drive, the buttons work again.
My key gets used every day. On leaving work the other day, the remote wouldn't work. On inspection it seems that a button got jammed down which I assume flattened the battery from transmitting all day. After a 15 minute drive, it hasn't missed a beat since.

EDIT:
Perhaps there is something in what Jxw has said above. From the Holden service manual:

After replacing a key due to a suspected discharged or faulty battery, first insert the key into the ignition and cycle
from OFF - ON - OFF. This is necessary as there may be a need to synchronise the rolling codes between the
remote coded key and the BCM. If the codes are not synchronised, the remote control of the central door locking
system will not work.

That doesn't make a lot of sense to me, that's not how I understood rolling codes to work, but it does seem to fit with my experiences.
My wife's key gets out of sync being unused for so long, and if my button was held down for so long, perhaps it transmitted so many times it got out of sync too.

 

[NeddyBear]

No thanks, I've ordered an original Holden key blank with the remote and contents off ebay.
I'll have that cut and programmed and fitted up in the engine bay.

 

[Jxfwsf]

I'll try and explain what i've worked out about the rolling codes, here's a screenshot of the code from a keyfob

The highlighted part is fixed and never changes once the key is programmed, all keys programmed to the same bcm will have the exact same hex here (this is the physical key in ignition part of the security)
If they are the original keys for the car this is also protected/locked and cannot be erased (even with the eprom removed from the circuit board and shoved in a burner)

All the other un-highlighted code (0001 0203 0809) is the rolling code that changes every X number of ignition cycles (is not protected and can be erased in a programmer), which once rolled the old unused key will be forgotten by the bcm, no 2 keys have the same code in these parts.
0001 & 0203 have been copies of each other in the dozen or so keys i read when i was playing around with them so assuming 0809 is the checksum.
I don't know what 0A0B is used for, it's only populated on original keys, copied or tech2 programmed keys are just FFFF.