Battery off reset

David3807 · 30th November 2007, 17:02

Think I need to try a reset this weekend cos

1/ Get ERR in the trip miles section of the IPK every now and again but usually goes when car restarted.

2/ Have replaced the vacuum pump on Cruise control but it still does not work. Thought a reset might do something for the cruise ECU before I replace everything else.

But which battery terminal do you disconnect ??

There seems to be different views on this if you read this

http://www.the75andztclub.co.uk/foru...ery+disconnect

Greeners · 30th November 2007, 17:10

I've always been an earth off first and on last kinda guy

T-Cut · 30th November 2007, 18:14

Negative (earth) terminal first is correct, but you really have to search around the Haynes manual for confirmation. Under the major heading 'Disconnecting the Battery' (page Ref 5), it elaborates on all the precautions you should take before actually disconnecting. It also describes the issues created by the disconnection, such as loss of throttle settings, fault codes, radio coding, etc. It also tells you how to run the engine afterwards to properly regenerate the throttle settings, but it never actually describes the disconnecting method. For that you have to look elsewhere. When you find it, it does indeed note that the Negative terminal should be disconnected first (and reconnected last if both terminals are involved). This prevents you accidentally shorting the battery with a spanner for example, when working on the positive terminal.
After disconnecting, at least 20 minutes should be allowed for the electronic systems to fully shut down in preparation for a reboot.

TC

comanche · 30th November 2007, 19:16

You should always disconnect the earth first for safety reasons.
by disconnecting the earth first if you should accidentally short the spanner to earth it wont matter.
if you disconnect the positive first and short the spanner to earth you will short the battery with a non fuse able link (IE the spanner) which could cause the battery to explode , and at the very least cause damage to you and the battery.

Robert

stocktake · 30th November 2007, 21:05

Quote:

T-Cut;113267 It also tells you how to run the engine afterwards to properly regenerate the throttle settings. TC

ooooooooooooo

Please tell, didn't know about that. Just disc for 20min, reconnect, off you go.

David3807 · 1st December 2007, 06:28

Thanks for the replies.

Would have replied earlier but the house had an enforced 'battery off reset' last night (ie total electricity out in the area) at 18.40hrs which was not cured until 05.00 this morning.

Thats the second time in 5 weeks around here.

T-Cut · 1st December 2007, 12:27

Quote:

Originally Posted by stocktake

Please tell, didn't know about that.

Disconnecting the battery causes the engine control module to lose idle speed data and other settings. These are 'learned' progressively and automatically when it's repowered and the car is driven. Until then the engine may run erratically and have poor performance. Here's what Haynes advises:
Start the engine and let it idle until it reaches normal running temperature.
Increase tickover to 1200 rpm for 2 minutes.
Drive car under varying conditions for about 5 miles.
This is usually sufficient to reset the ECM.

Independently powered 'memory/code savers' can be plugged into the cigar lighter socket to preserve these settings, as well as the radio code, immobiliser and other systems requiring stored data.

TC

David3807 · 1st December 2007, 14:53

You really got to laugh at the 75 OBC.

Battery off reset on the Tourer this AM. Left unconnected for about 30 minutes while I grabbed some breakfast and then reconnected.

Didnt get the ERR message anymore - good. Went for a drive for normal Sat AM chores tested Cruise - no difference . Well I didnt really expect the battery off to cure that but was hoping.

After last stop of the morning started engine and glanced at Range on the OBC - 1188 miles !!!! Nearly fell out of the car laughing .

Filled with petrol and reading came back to a believable 400 miles.

At least I have a matching pair now as my saloon will also play this trick every now an again.

30th November 2007, 17:02	#1
David3807 Posted a thing or two 2002 R75 Conn SE 2.5l Auto Tourer, 2001 R75 Conn SE 2.5 Auto Saloon Join Date: Nov 2006 Location: Gravesend Posts: 1,897 Thanks: 0 Thanked 2 Times in 2 Posts	Battery off reset Think I need to try a reset this weekend cos 1/ Get ERR in the trip miles section of the IPK every now and again but usually goes when car restarted. 2/ Have replaced the vacuum pump on Cruise control but it still does not work. Thought a reset might do something for the cruise ECU before I replace everything else. But which battery terminal do you disconnect ?? There seems to be different views on this if you read this http://www.the75andztclub.co.uk/foru...ery+disconnect Last edited by David3807; 1st December 2007 at 05:55..

30th November 2007, 17:10	#2
Greeners Moderator MG-ZTT Join Date: Mar 2007 Location: Ware, Herts Posts: 19,798 Thanks: 161 Thanked 1,249 Times in 1,036 Posts	I've always been an earth off first and on last kinda guy __________________ *David* Impecunity is the mother of ingenuity Useful how to's for common problems Car Of The Month Jan 2014 [SatNav Power Down] [Coolant Level] [SatNav Repair] [Diesel Non Starting] [Paint Codes] [Rear Light Seals] [Reversing Light Switch] [Bleeding Brakes][Sunroof Drain] [Early ZT's][Instrument Pack Diagnostics][ATC Diagnostics]

30th November 2007, 18:14	#3
T-Cut This is my second home Rover75 and Mreg Corsa. Join Date: Nov 2006 Location: Sumweer onat mote o'dust (Sagin) Posts: 21,754 Thanks: 341 Thanked 3,660 Times in 2,924 Posts	Negative (earth) terminal first is correct, but you really have to search around the Haynes manual for confirmation. Under the major heading 'Disconnecting the Battery' (page Ref 5), it elaborates on all the precautions you should take before actually disconnecting. It also describes the issues created by the disconnection, such as loss of throttle settings, fault codes, radio coding, etc. It also tells you how to run the engine afterwards to properly regenerate the throttle settings, but it never actually describes the disconnecting method. For that you have to look elsewhere. When you find it, it does indeed note that the Negative terminal should be disconnected first (and reconnected last if both terminals are involved). This prevents you accidentally shorting the battery with a spanner for example, when working on the positive terminal. After disconnecting, at least 20 minutes should be allowed for the electronic systems to fully shut down in preparation for a reboot. TC

30th November 2007, 19:16	#4
comanche Avid contributor Rover 75 Tourer 2.0 V6 Join Date: Apr 2007 Location: Mansfield , Notts Posts: 136 Thanks: 0 Thanked 6 Times in 1 Post	You should always disconnect the earth first for safety reasons. by disconnecting the earth first if you should accidentally short the spanner to earth it wont matter. if you disconnect the positive first and short the spanner to earth you will short the battery with a non fuse able link (IE the spanner) which could cause the battery to explode , and at the very least cause damage to you and the battery. Robert

1st December 2007, 06:28	#6
David3807 Posted a thing or two 2002 R75 Conn SE 2.5l Auto Tourer, 2001 R75 Conn SE 2.5 Auto Saloon Join Date: Nov 2006 Location: Gravesend Posts: 1,897 Thanks: 0 Thanked 2 Times in 2 Posts	Thanks for the replies. Would have replied earlier but the house had an enforced 'battery off reset' last night (ie total electricity out in the area) at 18.40hrs which was not cured until 05.00 this morning. Thats the second time in 5 weeks around here.

1st December 2007, 14:53	#8
David3807 Posted a thing or two 2002 R75 Conn SE 2.5l Auto Tourer, 2001 R75 Conn SE 2.5 Auto Saloon Join Date: Nov 2006 Location: Gravesend Posts: 1,897 Thanks: 0 Thanked 2 Times in 2 Posts	You really got to laugh at the 75 OBC. Battery off reset on the Tourer this AM. Left unconnected for about 30 minutes while I grabbed some breakfast and then reconnected. Didnt get the ERR message anymore - good. Went for a drive for normal Sat AM chores tested Cruise - no difference . Well I didnt really expect the battery off to cure that but was hoping. After last stop of the morning started engine and glanced at Range on the OBC - 1188 miles !!!! Nearly fell out of the car laughing . Filled with petrol and reading came back to a believable 400 miles. At least I have a matching pair now as my saloon will also play this trick every now an again.