problems with disconnecting positive terminal from battery first?

[feraldisco]

Hi - disconnected the positive terminal on my battery on 99 Td5 Disco on the weekend to clean up some grunge and apply vaseline. On reconnecting, everything seemed fine apart from having to enter the radio security code...all dash warning lights etc fine. However, there is now a clicking noise coming from the engine bay fuse box, even when the ignition is off - I can't pick out which fuse it is though. I then read my instruction manual (yes, I know, I should have done this first) and it indicated that negative should be removed before positive to avoid damaging ABS and other electrics. The ABS warning light on the dash turns on and off fine...so I hope I haven't done something stupid and expensive!?

Interestingly, the motor actually seems to run better now, so I'm wondering if the ECU has been reset (I thought you had to also remove the main fuse for about 5 mins for this to happen?)

Cheers

[LesDef]

Gidday feraldisco,

Can't help with details about the TD5 electrics.
When putting vaseline on the battery terminals it should not be placed on the contact surfaces. This may create a resistace. Just encase the exposed areas of the terminal to prevent oxidising.

Rgs Lesdef

[100I]

also can't give any help with TD5 specifics but general practice to remove -ve first and fit last to avoid accidental shorting with a spanner to the +ve.

[drivesafe]

Hi feraldisco, like the above, I can’t give you direct help with the noise but as stated above, always remove the battery’s negative terminal first and if you have a dual battery set up, no matter what type of isolator is in the system, including just a battery switch, you should also disconnect the auxiliary battery’s negative terminal as well and disconnect all battery negative terminals BEFORE you disconnect any positive terminals.

Also as posted above, connect ALL positive battery terminal before you connect ANY battery negative terminals.

Next, try disconnecting the negative terminal again and leave it off for a few minutes and then reconnect and see if the noise has gone.

Cheers.

[rovercare]

Gidday feraldisco,

Can't help with details about the TD5 electrics.
When putting vaseline on the battery terminals it should not be placed on the contact surfaces. This may create a resistace. Just encase the exposed areas of the terminal to prevent oxidising.

Rgs Lesdef

Vaseline-Petroleum jelly is fine for the contact surfaces

[lokka]

Id say that the disconecting of the battery would have reset your ecu each time u service them u should re set the ecu so it knows if theres a new filter or oil or what ever as things like filters become less effective and the computer makes allowances for it u need to re set them when things get replaced :D:D:D

[loanrangie]

Slightly ot, but are there any probs if disconnecting the battery on a tdi disco with the alarm or imobiliser ?

[rovercare]

Id say that the disconecting of the battery would have reset your ecu each time u service them u should re set the ecu so it knows if theres a new filter or oil or what ever as things like filters become less effective and the computer makes allowances for it u need to re set them when things get replaced :D:D:D

Where did you get that "information" from:eek:

Sounds like it came from an interesting source:angel:

[tombraider]

Where did you get that "information" from:eek:

Sounds like it came from an interesting source:angel:

Hmmm, yes... My BS detector just went off :wasntme:

[tombraider]

Mate.... Your giving engine management systems WAY to much credit!

[p38arover]

also can't give any help with TD5 specifics but general practice to remove -ve first and fit last to avoid accidental shorting with a spanner to the +ve.

Actually, that should read remove the earth/ground lead first - some cars (older ones) are positive earth. :p

Ron

[100I]

:oops2:

[p38arover]

:D:D

Pedantic bugger, ain't I?

Ron

[Andrew]

Why would it make anydifference as to which one you take off first, the car doesnt know what's positive and whats negative.

Taking the lead off just isolates the circuit.

[Bushie]

Good practice is to remove the earth (generally neg now) first that way you cannot short (big spark) to the body work when removing the power (pos) lead.

Believe me after blowing up a battery by shorting it out (in a confined space) its not something I would wish to do again.

refit is reversal ie power (pos) first for the same reasons.

The car may not know which is positive or negative BUT it does care.



Martyn

[DEFENDERZOOK]

:D:D

Pedantic bugger, ain't I?

Ron




thats not the exact word i would have used.........

i dont remember any +ve earth cars......... :angel:

[100I]

he he ha ha, you know I nearly said the same but wrote that a few times before settling on plain old 'polite'
LMAO

[p38arover]

thats not the exact word i would have used.........

i dont remember any +ve earth cars......... :angel:

Series Landies. My first car, my 3rd car, my 4th car, my 5th car, my 10th car. Almost any British car with a generator.

Ron

[Zute]

Maybe a bit off topic, but those felt pads Supercheap sell that go over the battery terminals, under the clamps, really work with reducing calcium build up.

[Quiggers]

Wont make a scrap of difference - the system is DC - as in 12Volt DC.

However, either terminal (secondarily) placed on to the battery post, softly, will arc and spark after the first connection, (potential damage area) ensure a hard contact - serious area! soft contact can
(by being on/off/on/off etc) upset 12VDC rails

any probs following would come from other sources, maybe asa result of incorrect procedure.....

digressing, jump starting any car with a computer is not a drama if you follow procedure - neg earth lead to both, dead car postive lead on, then live car positive lead on, then fire up live car, then fire up dead car.

do not tangle or even get near opposite pol

reverse procedure for discon after shut down of donor

do not try to jump start a diesel vehicle from a petrol vers - damage due to load issues

where you are? take off all, have a beer or a cup of tea, neg then pos, (clean terminals), then fire up, then boiling water on posts, then dry, then vaseline...

GQ

[p38arover]

Maybe a bit off topic, but those felt pads Supercheap sell that go over the battery terminals, under the clamps, really work with reducing calcium build up.

Umm, calcium? I think it would be a sulphate compound caused by leakage of the sulphuric acid electrolyte up past the terminal post/battery case seal.

I suspect the felt pads are charged with an alkaline solution of some sort.


Ron

[rovercare]

do not try to jump start a diesel vehicle from a petrol vers - damage due to load issues


GQ

More great "information":eek:

[100I]

I think what's more important when jump starting EFI vehicle is to load up the electrical system to minimise the chance of surges/spikes, so put the headlights on, run the a/c etc.
Don't know about diesel off petrol per se, but I'd imagine any HC or even large capacity engine will ask a lot from the donor.
The donor should always be running too.


Wont make a scrap of difference - the system is DC - as in 12Volt DC.

However, either terminal (secondarily) placed on to the battery post, softly, will arc and spark after the first connection, (potential damage area) ensure a hard contact - serious area! soft contact can
(by being on/off/on/off etc) upset 12VDC rails

any probs following would come from other sources, maybe asa result of incorrect procedure.....

digressing, jump starting any car with a computer is not a drama if you follow procedure - neg earth lead to both, dead car postive lead on, then live car positive lead on, then fire up live car, then fire up dead car.

do not tangle or even get near opposite pol

reverse procedure for discon after shut down of donor

do not try to jump start a diesel vehicle from a petrol vers - damage due to load issues

where you are? take off all, have a beer or a cup of tea, neg then pos, (clean terminals), then fire up, then boiling water on posts, then dry, then vaseline...

GQ

[rovercare]

Jump starting methods for starting EFI vehicles are all horse manure, Just jump it like normal, I've never killed anything yet, and I've done quite a few EFI engine conversions;)

Ever noticed what a car yard uses to jump start their cars?? never seen a trolley with a battery and trickle charger attached?hooked straight pos-pos neg-neg?.................All crap:D

Like I said, Its easy to gain an internet education:p but you can't believe everything:angel:

[Quiggers]

Leads melted, rovercare.

Glad it wasn't my car when the battery exploded...

...the guys trying to jump start the (diesel) minibus, from a petrol pootrol were, err, in the brown undies category:D

jumped a car from an ED Falcon, followed correct procedure and the coil pack type dizzy expired.......

GQ

[rovercare]

Leads melted, rovercare.

Glad it wasn't my car when the battery exploded...

...the guys trying to jump start the (diesel) minibus, from a petrol pootrol were, err, in the brown undies category:D

jumped a car from an ED Falcon, followed correct procedure and the coil pack type dizzy expired.......

GQ

A starting circuit is just a starter motor, their is nothing in there specific to a diesel engine, unless of course it........was 24VDC:angel:Care to explain the theory as to why its an issue??

ED's had hall effect distributors and a coil, EF's had coil packs.........coil pack type dizzy???

Not saying something in the ignition didn't croak!

[100I]

If u mean that loading the system is BS, that wasn't gleaned from the www and I'm almost certain it says the same thing in the book for my car. Note to self, check it sometime.

[HAK]

Mate.... Your giving engine management systems WAY to much credit!


WOW I thought C-P-3-O was running the CPU I alomost bought it :D:D:D:D

[rovercare]

If u mean that loading the system is BS, that wasn't gleaned from the www and I'm almost certain it says the same thing in the book for my car. Note to self, check it sometime.

Yea, but its just like connecting the neg lead to the engine block, its a ****ing joke, that thing is a great conductor and offers no resistance to currect flow, surges, the only thing it MAY offer is a little electrolysis:D

Theory is a great thing to know and you always should learn the "correct" way of doing things first, that way you can learn the actual way and what unnecassary methods are simply theory;)

I'm stepping out of this for a lil' while:angel:

[100I]

Yea, but its just like connecting the neg lead to the engine block, its a ****ing joke, that thing is a great conductor and offers no resistance to currect flow, surges, the only thing it MAY offer is a little electrolysis:D

Theory is a great thing to know and you always should learn the "correct" way of doing things first, that way you can learn the actual way and what unnecassary methods are simply theory;)

I'm stepping out of this for a lil' while:angel:

So are you perhaps saying that this proceedure just harks back to early days of vehicle ECUs when they were new and scary so people were extra cautious, but in the real world things are in fact a whole lot simpler?
Or maybe it is a safeguard in a worst case scenario, perhaps if the battery is totally cooked or collapsed as opposed to having left the headlights on and it's just too low to crank.
You're right, in anything there are always short cuts if you understand the rules of the game.
I'm interested to know.
Say I'm stuck somewhere and all I can jump off is a pretty weak donor so loading my system is therefore a problem. But frying my ECU is a problem. Where's the tipping point?

[rovercare]

So are you perhaps saying that this proceedure just harks back to early days of vehicle ECUs when they were new and scary so people were extra cautious, but in the real world things are in fact a whole lot simpler?
Or maybe it is a safeguard in a worst case scenario, perhaps if the battery is totally cooked or collapsed as opposed to having left the headlights on and it's just too low to crank.
You're right, in anything there are always short cuts if you understand the rules of the game.
I'm interested to know.
Say I'm stuck somewhere and all I can jump off is a pretty weak donor so loading my system is therefore a problem. But frying my ECU is a problem. Where's the tipping point?

Well done, you took that all the right way:)

I've been playing with EFI cars for atleast 7 years, engine conversions etc
And i've NEVER killed anything to do with any ECU or assosciated parts, The only procedure I have with jump starting is making sure you hook pos-pos and neg-neg:D

So you've pretty much answered your on questions above, much better than I would have:eek:

[100I]

ok so don't take this the wrong way; are you speaking from a tech background, or of the dozen or so times you've had to jump a car over the years none of them have blown up?
I just came up with possible theorys, it's not word.
If anyone can give a tech answer either way I'm interested.

[rovercare]

ok so don't take this the wrong way; are you speaking from a tech background, or of the 100's or so times you've had to jump a car over the years none of them have blown up?
I just came up with possible theorys, it's not word.
If anyone can give a tech answer either way I'm interested.

And alot of it can be based around an electrical background, Frying the EFI components is possible in theory, But when does it happen???

Also jumping a Diesel from a petrol is just crazy, jumped plenty without issue, even 24VDC patrols - just jump the 1 battery:o All without fault

[100I]

I read the diesel bit again, fair chance that a bus was 24v or could even have been just $2 jump leads that expired, or reverse polarity, could have been anything.

oh.. and... HIJACK OFF:D

[rovercare]

oh.. and... HIJACK OFF:D

:angel::wasntme:

[beforethevision]

My money is with ROVERCARE, it doesnt make sweet fa difference. Just dont touch 12 to 0v when connecting/disconnecting. Similarly when jumping, start the good car first purely due to increased voltage -> lower required current ->less likely to burn out leads when jumping dead car. And between 20$ leads and 100$ leads, its actually worth getting a good set.

Much bs floating aroud regarding electrics. suprisingly little damage that can be done. All ecus have power regulation to 8v inside. if you are over, its sweet. If you are under, the rest of the electrics probably wont work either.

[Andrew]

Umm, calcium? I think it would be a sulphate compound caused by leakage of the sulphuric acid electrolyte up past the terminal post/battery case seal.

I suspect the felt pads are charged with an alkaline solution of some sort.


Ron





and a bit of lead oxide as well as some copper oxide ( thats the green)

[Andrew]

"do not try to jump start a diesel vehicle from a petrol vers - damage due to load issues"


NO



The size of the battery , is the real issue and the oomph through the Jumper leads, not whether it is diesel or not as the alternator is not supplying all the power other wise the vehicle would stall every time you tried to jump another.

[CraigE]

Basically by removing positive cable first arcing / sparking can occur and cause explosive results with gases from battery, fire and damage to fuses, relay and any sensitive electrical equipment. Is basic common knowledge. Removing earth cable first eliminates the arcing.
Personally I have seen a few melted batteries, fires and explosions and injuries resulting due to positive cables arcing. Just because you get away with it 30 times does not make it safe or mean that you will always get away with it. Better to err on the side of caution for something that takes no longer.
It is not common for electrical damage but can occur. Usually fuses, relays, fuseable links, circuit breakers, but I have also seen it destroy car stereos and the like.
First thing we do at a vehicle accident is disconnect the earth cable, not cut.


Why would it make anydifference as to which one you take off first, the car doesnt know what's positive and whats negative.

Taking the lead off just isolates the circuit.

[p38arover]

Basically by removing positive cable first arcing / sparking can occur and cause explosive results with gases from battery, fire and damage to fuses, relay and any sensitive electrical equipment. Is basic common knowledge. Removing earth cable first eliminates the arcing.


Now my background is electronics but not car electrics but this doesn't make sense. :)

Highlight 1: What do you do on a positive earth car. Yes, they aren't common but they are still around on older British stuff.

Highlight 2: Whose basic common knowledge? I've been an a electronics tech since 1965 and I've never heard of it so it can't be basic common knowledge.

Highlight 3: The only way I can see an arc occurring is that the spanner slips and shorts the positive terminal to ground.

The current drawn through the positive and negative terminals must be the same so the arcing should be the same.

Have a read of http://forums.firehouse.com/showthread.php't=84623 - you can see other rescue service guys aren't sure either and have been taught different things. Note the comment about a punctured battery still providing a ground circuit.

Ron

[Captain_Rightfoot]

Now my background is electronics but not car electrics but this doesn't make sense. :)

Highlight 1: What do you do on a positive earth car. Yes, they aren't common but they are still around on older British stuff.

My 1969 Lotus is negative earth. Surely they would be a very very tiny proportion of the total vehicle pool?



Highlight 3: The only way I can see an arc occurring is that the spanner slips and shorts the positive terminal to ground.

I can assure you this is quite exciting though :eek::D

[vnx205]

I've been an a electronics tech since 1965

Ron

Go on, your kidding me aren't you? Did we have electronics back in the middle of last century? Weren't things driven by steam or horses back then. :p

[p38arover]

Go on, your kidding me aren't you? Did we have electronics back in the middle of last century? Weren't things driven by steam or horses back then. :p

We didn't call it electronics then. I was trained as a radio technician!

I learned a lot about valves - transistors were new. I remember an instructor telling us that transistors wouldn't last.

Ron

[barryj]

Believe me after blowing up a battery by shorting it out (in a confined space) its not something I would wish to do again.

Martyn

I'm with you Bushie. I borrowed a set of jumper leads, about 20 m long and thick as a garden hose and greasy as Adelaide chips, and a ute from and auto 'lecky in Dalby once on a Saturday arvo.

Connected red to red, black to black and kaboom. Checked out the clamps, they were wired the wrong way, red to black and black to red.

Went back to the workshop and he said "yeah, I must fix that one day". What size battery do you want to buy? Nice guy!

[drivesafe]

Brother, this topic always ends in a debate of some form.

In a nut shell, if you have a new vehicle, READ THE MANUAL BEFORE YOU DO ANYTHING.

Now to reality, as Tombraider posted, you are giving engine management systems way to much credit.

I’ve been in this game for over 30 years and I have never heard of a car computer stuffing up while jump starting and before everybody starts jumping up and down, I’m not saying it won’t happen but there are some simple things to do that dramatically reduce the chances of doing damage.

If you end up with a flat battery NOTE NOT A STUFFED BATTERY, just a flat battery because you left the headlights on, to jump start, first make sure everything is turned off in the vehicle with the flat battery, ESPECIALLY THE IGNITION.

Connect the battery leads between the two vehicles and I usually leave the host vehicle’s motor running ( personal preference ).

With power now connected to the flat battery, again make sure everything is turned off, like your sound system and headlights.

DO NOT TRY TO START THE VEHICLE YET.

Leave the two vehicles connected for a few minutes to allow some charge to get back into the flat battery. By doing this, the host vehicle is not trying to charge a dead flat battery and start the vehicle at the same time.

After a few minutes, try starting the vehicle, if it starts, disconnect the jumper leads and off you go.



Highlight 3: The only way I can see an arc occurring is that the spanner slips and shorts the positive terminal to ground.

Ron

Ron, you actually answered the query. The reason for disconnecting the neg first is the it is easy to fumble with a spanner or what ever and doing so while disconnecting the neg will have no effect and once the neg is disconnected, fumbling while disconnecting the positive will now also have no effect.

It’s just done because so many auto electricians seem to be clumsy :wasntme:

[rovercare]

Basically by removing positive cable first arcing / sparking can occur and cause explosive results with gases from battery, fire and damage to fuses, relay and any sensitive electrical equipment. Is basic common knowledge. Removing earth cable first eliminates the arcing.
Personally I have seen a few melted batteries, fires and explosions and injuries resulting due to positive cables arcing. Just because you get away with it 30 times does not make it safe or mean that you will always get away with it. Better to err on the side of caution for something that takes no longer.
It is not common for electrical damage but can occur. Usually fuses, relays, fuseable links, circuit breakers, but I have also seen it destroy car stereos and the like.
First thing we do at a vehicle accident is disconnect the earth cable, not cut.

Damaging fuses and relays from disconnecting the pos first, hahahaha is that a joke???? hope so because its funny:wheelchair::lol2::no2:

Negative terminal still arcs. being DC you'll have a potential still up to the negative terminal until its connected, but anyway we wont get into electrical theory:o

The only legitimate concern you have there is an explosion, caused by released gases from the battery;)

[feraldisco]

didn't think this would cause so much discussion! Seems like disconnecting the positive first isn't such a huge issue as I am very careful not to accidently connect the positive terminal to any bodywork/earth point. Still doesn't explain the subsequent clicking noise from the fusebox, but I guess Graeme (Cooper) and his electronics analysis will work out what that is...as well as whatever is causing the miss at idle - hopefully not the dreaded oil in wiring loom...if it all checks out (only owned the vehicle for a month...and still on first tank of juice...), I'm off to tombraider for an ECU extreme makeover...

[Bushie]

The only legitimate concern you have there is an explosion, caused by released gases from the battery;)

Been there, done that, under an RLHC Bedford. Not keen on revisiting :eek::eek:


Martyn