A nice easy question, I imagine.

BRG75 · 11th July 2022, 10:39

Yesterday I disconnected the battery on my Tourer, a late pre-facelift CDTi.

As I loosened of the negative clamp, but with it still in situ., I heard a single beep, almost certainly from the plenum chamber area.

When reconnecting, all was OK & normal.

Part of the alarm system?

Info. appreciated.

Regards

Mike

Lee T · 11th July 2022, 10:53

Battery back up sounder possibly!

coolguy · 11th July 2022, 11:18

Usually the alarm system in my experience (currently 4 75s and 2ZTs) so plenty of similar situations!

planenut · 11th July 2022, 17:20

The alarm horn is sited in the plenum chamber on the nearside.

rab60bit · 11th July 2022, 21:38

Quote:

Originally Posted by BRG75

Yesterday I disconnected the battery on my Tourer, a late pre-facelift CDTi.

As I loosened of the negative clamp, but with it still in situ., I heard a single beep, almost certainly from the plenum chamber area.

When reconnecting, all was OK & normal.

Part of the alarm system?

Info. appreciated.

Regards

Mike

Did you already have the positive lead disconnected before loosening the negative clamp?

BRG75 · 12th July 2022, 10:22

No, I always disconnect the negative first (and reconnect the negative last)

I think that Lee T was the first on the button with the battery backup sounder.

I've now looked on my RAVE CD, thinking that I will see what exactly this unit does.

It is multi functional, and needs to be configured using Testbook. Incidentally, MGR call it a Siren.

Not having Testbook, I delved deeper into this forum, and it seems that it is to do with warning the owner that the main battery voltage is getting low. (WRONG - please see my later post no. 8)

Fortunately the car is AOK (in this area, at least) and I'm just being inquisitive; whilst I've heard of Testbook. I don't even know what it is.

Any further info?

Regards

Mike

BRG75 · 12th July 2022, 11:59

Just found (in the 2001 Accessories Price List) that it's listed as a sounder, i.e. not a siren, as on RAVE.

Regards

Mike

BRG75 · 12th July 2022, 15:15

I've now found more about this on RAVE.
Pages 86-5-10 & 86-5-11 go into the full technical aspect, but I precis below the basics, and hope that I'm not stating what is common knowledge.

First of all, it does NOT indicate a low battery (my post No. 6)

It is part of the alarm system, but is also used to indicate a mis-lock of the car i.e. that a door or the bonnet / boot is not fully shut.

Dependant upon which market the car is destined for, and / or the original purchaser's order, the car MAY have ONE of two basic alarm sounders available; both being located in the passengers side plenum chamber.

The first is called an ALARM SOUNDER.
The second is called the BATTERY BACKED-UP SOUNDER (BBUS)
Also variously called Battery Back Up Sounder / Siren

Each has it's own dedicated, integral, "horn".
Both are driven by the Body Control Unit (BCU) to indicate an alarm trigger.

The big difference (only difference?) is that the BBUS is tamper proof, by virtue of having an inbuilt re-chargeable battery.

I think of significance, is that if activated quote "for more than 30 seconds, internal software within the BBUS will stop the sounder operation"

I guess that they mean firmware, but they do apparently fail, hence one forum comment about taking it off the car altogether; and at least one other talking about water damage.
In other words it's internal fail safe, can fail.

Staying with the BBUS,
There are clearly more than one type that have been fitted over the years (re-designs?)

I hope this helps.

Regards

Mike

BRG75 · 12th July 2022, 15:53

Final comment / question on this, and the answer??

The BBUS is switched on it's negative side (RAVE write up) and is looking for a disturbance to the car's electrics (electronics?)

When I loosened off the negative terminal, might I have transmitted a static discharge from my body? quite likely.

In my IT days (engineering) we always wore a wrist strap to earth ourselves to whatever PCB we might be working on.
Similarly, all soldering irons had their earth disconnected / isolated.

Are they now needed in the garage?

I might have to order myself one.

Regards

Mike

MarkS · 12th July 2022, 17:04

1) The chances are that the rechargeable battery in the BBUS will have long since completely failed due to electrolyte leakage.

2) If you grabbed hold of the negative terminal before disconnecting, you will have discharged any static in your body.

3) Don't wear ladies nylon underwear when working on your car.

11th July 2022, 10:39	#1
BRG75 Gets stuck in Rover 75 Saloon & Tourer, 9th & 10th Rovers Join Date: Nov 2013 Location: Sevenoaks Posts: 973 Thanks: 670 Thanked 290 Times in 195 Posts	A nice easy question, I imagine. Yesterday I disconnected the battery on my Tourer, a late pre-facelift CDTi. As I loosened of the negative clamp, but with it still in situ., I heard a single beep, almost certainly from the plenum chamber area. When reconnecting, all was OK & normal. Part of the alarm system? Info. appreciated. Regards Mike __________________ Presently 2004 75 CDTi auto Connoisseur Tourer - White Gold 2001 75 2.5 auto Connoisseur Saloon - White Gold Previously 2002 75 1.8 auto Club SE, 2000 75 1.8 auto Classic SE (Company Car) 1997 420 (Company Car) 1996 216 cabriolet, 198? 213 VDP 1986 SD1 V8 VDP, 1968 2000TC, 1966 2000.

11th July 2022, 10:53	#2
Lee T Gets stuck in MG ZT Join Date: Jul 2014 Location: Liverpool Posts: 850 Thanks: 180 Thanked 248 Times in 189 Posts	Battery back up sounder possibly! __________________ [SIGPIC][/SIGPIC]

12th July 2022, 10:22	#6
BRG75 Gets stuck in Rover 75 Saloon & Tourer, 9th & 10th Rovers Join Date: Nov 2013 Location: Sevenoaks Posts: 973 Thanks: 670 Thanked 290 Times in 195 Posts	No, I always disconnect the negative first (and reconnect the negative last) I think that Lee T was the first on the button with the battery backup sounder. I've now looked on my RAVE CD, thinking that I will see what exactly this unit does. It is multi functional, and needs to be configured using Testbook. Incidentally, MGR call it a Siren. Not having Testbook, I delved deeper into this forum, and it seems that it is to do with warning the owner that the main battery voltage is getting low. (WRONG - please see my later post no. 8) Fortunately the car is AOK (in this area, at least) and I'm just being inquisitive; whilst I've heard of Testbook. I don't even know what it is. Any further info? Regards Mike __________________ Presently 2004 75 CDTi auto Connoisseur Tourer - White Gold 2001 75 2.5 auto Connoisseur Saloon - White Gold Previously 2002 75 1.8 auto Club SE, 2000 75 1.8 auto Classic SE (Company Car) 1997 420 (Company Car) 1996 216 cabriolet, 198? 213 VDP 1986 SD1 V8 VDP, 1968 2000TC, 1966 2000. Last edited by BRG75; 12th July 2022 at 15:35..

12th July 2022, 11:59	#7
BRG75 Gets stuck in Rover 75 Saloon & Tourer, 9th & 10th Rovers Join Date: Nov 2013 Location: Sevenoaks Posts: 973 Thanks: 670 Thanked 290 Times in 195 Posts	Just found (in the 2001 Accessories Price List) that it's listed as a sounder, i.e. not a siren, as on RAVE. Regards Mike __________________ Presently 2004 75 CDTi auto Connoisseur Tourer - White Gold 2001 75 2.5 auto Connoisseur Saloon - White Gold Previously 2002 75 1.8 auto Club SE, 2000 75 1.8 auto Classic SE (Company Car) 1997 420 (Company Car) 1996 216 cabriolet, 198? 213 VDP 1986 SD1 V8 VDP, 1968 2000TC, 1966 2000.

12th July 2022, 15:15	#8
BRG75 Gets stuck in Rover 75 Saloon & Tourer, 9th & 10th Rovers Join Date: Nov 2013 Location: Sevenoaks Posts: 973 Thanks: 670 Thanked 290 Times in 195 Posts	I've now found more about this on RAVE. Pages 86-5-10 & 86-5-11 go into the full technical aspect, but I precis below the basics, and hope that I'm not stating what is common knowledge. First of all, it does NOT indicate a low battery (my post No. 6) It is part of the alarm system, but is also used to indicate a mis-lock of the car i.e. that a door or the bonnet / boot is not fully shut. Dependant upon which market the car is destined for, and / or the original purchaser's order, the car MAY have ONE of two basic alarm sounders available; both being located in the passengers side plenum chamber. The first is called an ALARM SOUNDER. The second is called the BATTERY BACKED-UP SOUNDER (BBUS) Also variously called Battery Back Up Sounder / Siren Each has it's own dedicated, integral, "horn". Both are driven by the Body Control Unit (BCU) to indicate an alarm trigger. The big difference (only difference?) is that the BBUS is tamper proof, by virtue of having an inbuilt re-chargeable battery. I think of significance, is that if activated quote "for more than 30 seconds, internal software within the BBUS will stop the sounder operation" I guess that they mean firmware, but they do apparently fail, hence one forum comment about taking it off the car altogether; and at least one other talking about water damage. In other words it's internal fail safe, can fail. Staying with the BBUS, There are clearly more than one type that have been fitted over the years (re-designs?) I hope this helps. Regards Mike __________________ Presently 2004 75 CDTi auto Connoisseur Tourer - White Gold 2001 75 2.5 auto Connoisseur Saloon - White Gold Previously 2002 75 1.8 auto Club SE, 2000 75 1.8 auto Classic SE (Company Car) 1997 420 (Company Car) 1996 216 cabriolet, 198? 213 VDP 1986 SD1 V8 VDP, 1968 2000TC, 1966 2000. Last edited by BRG75; 12th July 2022 at 15:26..

11th July 2022, 11:18	#3
coolguy Coolguy Rover 75 CDT Tourer Auto, Rover 75 2.0 Connoisseur Auto, MG ZT 2.5 Auto and MG ZT Cdti Auto (Monogra Join Date: Nov 2009 Location: Finedon Posts: 1,896 Thanks: 933 Thanked 638 Times in 430 Posts	Usually the alarm system in my experience (currently 4 75s and 2ZTs) so plenty of similar situations!

11th July 2022, 17:20	#4
planenut Regional Secretary Rover 1.8T Tourer Join Date: May 2007 Location: Heathrow Posts: 6,948 Thanks: 1,551 Thanked 2,036 Times in 1,264 Posts	The alarm horn is sited in the plenum chamber on the nearside.

12th July 2022, 15:53	#9
BRG75 Gets stuck in Rover 75 Saloon & Tourer, 9th & 10th Rovers Join Date: Nov 2013 Location: Sevenoaks Posts: 973 Thanks: 670 Thanked 290 Times in 195 Posts	Final comment / question on this, and the answer?? The BBUS is switched on it's negative side (RAVE write up) and is looking for a disturbance to the car's electrics (electronics?) When I loosened off the negative terminal, might I have transmitted a static discharge from my body? quite likely. In my IT days (engineering) we always wore a wrist strap to earth ourselves to whatever PCB we might be working on. Similarly, all soldering irons had their earth disconnected / isolated. Are they now needed in the garage? I might have to order myself one. Regards Mike __________________ Presently 2004 75 CDTi auto Connoisseur Tourer - White Gold 2001 75 2.5 auto Connoisseur Saloon - White Gold Previously 2002 75 1.8 auto Club SE, 2000 75 1.8 auto Classic SE (Company Car) 1997 420 (Company Car) 1996 216 cabriolet, 198? 213 VDP 1986 SD1 V8 VDP, 1968 2000TC, 1966 2000.

12th July 2022, 17:04	#10
MarkS Gets stuck in Rover 75 Diesel Tourer, called Perseverance Join Date: Nov 2011 Location: Bournemouth Posts: 664 Thanks: 189 Thanked 157 Times in 108 Posts	1) The chances are that the rechargeable battery in the BBUS will have long since completely failed due to electrolyte leakage. 2) If you grabbed hold of the negative terminal before disconnecting, you will have discharged any static in your body. 3) Don't wear ladies nylon underwear when working on your car. Last edited by MarkS; 12th July 2022 at 17:11..