Flat battery/Immobiliser help!!

[Davey Blueeyes]

Hello! I have a '99 LS400 and its lovely! However I have a Battery drain issue that it's going into the garage for tomorrow. If I can get it there!

The immediate issue is how to start the thing! Battery is stony flat after 3 days no use, new Battery last Aug. Not just lazy cranks, totally dead, everything. Now I have a booster pack, engine turns fine when that's on but doesn't start because the immobiliser stops it.

So I follow the procedure, leave the key turned to the 'ON' position for six minutes. I have to leave the Battery booster on as otherwise the ECU will die. Once six minutes have elapsed, booster is out of charge so can't start the engine! And it's a Noco Boost Plus GB40 so it's not a rubbish one.

Taking the Battery off to charge is not an option.

Any ideas? Plus it is the 'ON' position for six minutes, is it not??

[Herbie]

Your profile says that you also have an SC430 so take the Battery off that (or use jump leads) to start the LS?

[Davey Blueeyes]

Great idea, sadly it's in the garage in Brighton having a new exhaust and coilovers fitted 😂😂

I do have my RX400h but I know I can't jump from that

[Herbie]

31 minutes ago, Davey Blueeyes said:

Great idea, sadly it's in the garage in Brighton having a new exhaust and coilovers fitted 😂😂

I do have my RX400h but I know I can't jump from that

You could if you either take the Battery out or just disconnect it from the car before using it to jump the other one.

The problem potentially arises if the recipient car attempts to draw too much current from the hybrid's DC/DC converter but if the hybrid system is off or the Battery is completely disconnected from the hybrid, that's fine.

[Davey Blueeyes]

I might give that a go, thanks Herbie.

Am I right in thinking that leaving the key in the 'on' position for 6 minutes is the correct procedure for this?

[Herbie]

Just now, Davey Blueeyes said:

I might give that a go, thanks Herbie.

Am I right in thinking that leaving the key in the 'on' position for 6 minutes is the correct procedure for this?

I've never personally done that David so I'm not sure. I can't really see what benefit it would give, to be honest.

I can see a use for leaving the donor Battery connected to the flat one for 5 or 10 minutes. That would give the flat one some charge of its own first, so that the alternator doesn't have to work absolutely flat out as soon as the engine fires, but I just don't see any advantage in having the key in the 'on' position.

[ColinBarber]

33 minutes ago, Davey Blueeyes said:

Am I right in thinking that leaving the key in the 'on' position for 6 minutes is the correct procedure for this?

If your vehicle has lost its immobiliser programming then it will learn the key in the lock after around 6 minutes. You don't need to do it if the security light goes out when you put the key in the ignition. If it remains on/flashing then the immobiliser is still active and therefore the vehicle won't start.

[Howplum]

This is the reset procedure in my 1996, if it helps.

[Davey Blueeyes]

4 hours ago, ColinBarber said:

If your vehicle has lost its immobiliser programming then it will learn the key in the lock after around 6 minutes. You don't need to do it if the security light goes out when you put the key in the ignition. If it remains on/flashing then the immobiliser is still active and therefore the vehicle won't start.

Yes, mine loses the coding when the Battery goes flat. I can't remember the exact procedure but I'm sure it involves turning the key to on and leave for 6 minutes.

The annoying thing is my booster pack is flat at about 5 mins and 40 seconds 🙂

 

[ColinBarber]

Sounds like your Battery needs replacing - possibly has a short in it if it is going flat that quickly unless there is a substantial drain elsewhere. I think you are going to need a reasonable sized lead acid Battery to jump from - if your Battery is that flat any small booster pack will be drained charging your Battery if you have to leave on for 6 minutes.

[runsgrateasanut]

The LS400 starts without a difficulty and locking by key is OK but locking by Fob button is not working.  I have tried the six minutes with ignition "on" and extracating the ignition key, the light does not appear.  Close the Door and lock with the key and the Immobiliser light comes on and stays without flicker for twenty seconds and then starts to flicker on and off.  Try the key  fob "unlock" button but it doesn't work no matter where I point it.  Not tried to enter the Boot without first unlocking but suppose thats the only way to find out if the Car is truly "immobilised"  Neighbours won't be pleased.  Any other way perhaps?

[Malc]

Stuart, you're a miserable failure for sure ......  you just didn't do all this while standing on your hands eating a banana and drinking a fizzy coke thru a straw ........ 

20 minutes ago, runsgrateasanut said:

Any other way perhaps?

 I don't know, when will we ever learn ..........  hehehehehe 

Malc

[runsgrateasanut]

Don't tease me Malc I'm still recovering from having to get up at 9 O'clock this Morning to recover the Car from the Garage after the work to pass the MOT !

[Malc]

Oh my ..  do tell, what was the " damage " ?

Malc

[runsgrateasanut]

I was quoted around £300 and I must say I was very pleasantly surprised when asked to pay £300 which included the VAT.  A pass, clearing the MOT rust fail points but leaving still a list of other possibly over zealous examination of rust weaknesses to be looked at during warmer times.  Car on SORN pending end of Tax on the GS and likely disposal.

[royoftherovers]

1 minute ago, runsgrateasanut said:

I was quoted around £300 and I must say I was very pleasantly surprised when asked to pay £300 which included the VAT.  A pass, clearing the MOT rust fail points but leaving still a list of other possibly over zealous examination of rust weaknesses to be looked at during warmer times.  Car on SORN pending end of Tax on the GS and likely disposal.

Congratulations Stu and all of the best for Christmas and the New Year.

[BigBoomer]

She's home and once again road legal. Crack open the Champers and party like it's 2021 

[runsgrateasanut]

2 hours ago, royoftherovers said:

Congratulations Stu and all of the best for Christmas and the New Year.

Thanks John, and all the best to you and your family.

[Popeye292]

I have the exact problem with my 300gs your booster is probably not flat but just turning itself off. I have searched the market for a booster that will reset the immobiliser and then crank the engine… back to the stoneage and jump leads