[99P38]

Novice question: (1) there seems to be some mystery around disconnecting and reconnecting the battery. RAVE says to do the 17 seconds thing before disconnecting; I've seen others say they've never had to do that. Is there a final word on the 17 second disconnect? // (2) Also, upon reconnecting, the owner's manual mentions re-establishing sunroof and window settings, radio code, alarm settings — all of this has me sketched out about disconnecting the battery. Am I over thinking it or taking necessary precautions? // (3) Do people use memory savers, and if so, any recommendations on which one to use? If there is a thread on these questions already and I've missed it (I've searched under OBD, memory saver and come up empty), please link, and thanks for your patience.

 

[RRToadHall]

Well, you have got me. I've never hear of a 17 second thing or find any mystery. Standard battery safety applies. If you have Navigation you have to wait for navigation computer in the back to fully complete its shut down procedure that takes several minutes. As far as windows etc, That is just usual "XX window not set" procedures.

I guess it all depends on why you are disconnecting your battery. If you are disconnecting to clear an error code it doesn't work on a P38. Neither does a "hard reset" of touch the cables together. If you need to change your battery due to age or a dead cell you can maintain power by hooking up your battery charger to the cables. I don't think I've ever had to reset windows, reprogram the radio or the such because the battery is not unhooked long enough.

 

[99P38]

I'm disconnecting to tackle the soldering issues at the fusebox. (https://www.rangerovers.net/repairdetails/electrical/fusebox.html) And that means the battery will be disconnected for a few hours at least. This is why I still have the question about memory savers and if people use them. Thx.

See RAVE's 17 seconds procedure here: http://roverpix.blogspot.com/2018/07/17-seconds.html

 

[Bolt]

If you are going to remove the fuse box, a memory saver is pointless as well as dangerous since you will be removing all the power feed lines to all sub systems, and with an external feed, the terminals at the fuse box will be still be live. not a good idea.
Just be sure the truck is unlocked, and not in any sort of alarmed state, and remove the battery.
Re setting the windows and sunroof is no big deal, and takes all of about a minute.
You may or may not need a radio code...On a 99, I am not positive, and of course you will need to re sync the fobs. Again, simple and takes 10 seconds.
As for the 17 second thing? This applies only to trucks with an alarm battery back up. To the best of my knowledge, NAS haven't ever had this battery fitted, so it does not apply.
Just be sure, if you have Nav, as TH said. Wait several minutes after shutting of the ignition before removing the battery or you can crash the Nav computer.....Terminally........

 

[99P38]

Fuse box will still be live, okay. I wasn't sure if memory savers completed some kind of local circuit, but it sounds like memory savers are basically the same thing as attaching jumper cables to a second battery. The whole electrical system behaves as if the battery was never disconnected. Why didn't I think of that? Because I'm a woodworker, not a mechanic. (It's all mysterious if you've never done it before). 8~

Thanks Bolt.

 

[Richard_G]

Yeah you've got it, a memory saver is exactly the same as attaching jumper cables to the battery terminals before disconnecting them from the battery. One wouldn't help you anyway as the circuits would still be broken as soon as you disconnect the fusebox. As said, some cars for some markets had an alarm sounder with an internal battery so it would still sound if someone chopped the battery cable to prevent to alarm going off when they tried to steal the car. The ignition on, ignition off and disconnect within 17 seconds is a sequence programmed into the alarm so it doesn't go off when you disconnect the battery. As Bolt has already said, as long as the car is unlocked and not in an alarmed or immobilised state when you disconnect the battery, you won't have any problems when you reconnect.

 

[RRToadHall]

LMAO. Yea, the asthmatic goose hooter for "alarm"with a battery back up that is dead on every example that was equipped with it. You would think they would have used something that didn't make you feel sorry for the Rover.

 

[ColoradoCrow]

I just replaced the fuse box in my NAS
2002. I disconnected the battery and covered it with a towel to prevent shorting with tools or an accidents. Replaced the fuse box with a new one. Added new relays and reconnected. I had to reset all the windows and sunroof but that took under 2 mins for all of them. Just open and fully close each on one at a time. The key fobs but in the door and lock and unlock the door to resync the fob
repeat with the other fob and your done. Pretty easy.
Good luck. Take your time and clean everything as you go.

 

[Ecco]

..17 seconds procedure is correct..

1) Unlock car
2) turn on key(no engine start)
3) turn off key
4) 17 seconds to unplug battery

Other way which is legit and doesn't involve 17 seconds is simply, unlock car with keyfob, wait some 20 seconds and remove battery(do not lock any door manually, just let it be unlocked)..thats it..later just set back sunroof, windows, radio..

..it seems to be very identical procedure for defender 2.2 puma (both 17 secs as well as unlock/replace)..

 

[RRToadHall]

Ecco, Yes it is correct but it only applies to two early GEMS years of P38 and will brick any P38 navigation system. Like wise waiting only 20 seconds will brick any P38's nav system. Procedures for early GEMS often differ from Bosch systems.

So getting back on topic, now that we know he is removing the fuse box to attempt repairs, there is no safe way to keep the power live.