Technical ECU - Don't Jump Start!

[AndyCr15]

Ever since my battery went flat around 6 months ago, I've had the engine warning light come on and stay on all the time. I figured it just needed resetting, thinking it came on because the battery had died.

Yesterday I took my Stilo in to get the air con fixed (£433!!! ) and they tell me the ECU has gone and that's another £381!!!

Accepting the air con probably does have leeks (they re-gassed it last year... under warranty) I thought maybe they are trying it on with the ECU thing, I called another garage and checked things out. Prices seem to match up, if that's really whats wrong, but I explained I thought it just needed resetting. The guy then asked, when the battery went flat, did I just start it? I told him I did and he said your not supposed to jump start these cars, that will have knackered the ECU!

Can anyone confirm this? I'm thinking I'll need to get it all fixed, but as sometimes I don't use my car for a week or two at a time, it concerns me the battery may go again at some point... I wouldn't want to break the damn ECU again though...

 

[Bo~Select@]

Thing is how do you start the car car if the battery goes flat wait for a charger to charge the battery ?

 

[ProtoFJ]

most important thing when jump starting modern cars is DO NOT connect direct from battery to battery !

connect Battery positive terminals together but NOT negative. connect between 2 good earths - I tend to use a ahndy lug on the engine casing.

the problem is that if you go direct from batt to batt you can fry the ECU - seen it done many times - Ford Galaxy was the worst for it!

 

[Deckchair5]

Connecting another battery won't fry the ECU
What fries the ECU is connecting an electrical booster starter to the battery when it's still electrically connected to the car.

Jump starting is fine as long as you follow the routine below.

Connecting two batteries terminal to terminal is mostly bad news because there is a high risk of battery explosion and eye damage with acid so never do that .

Your choices are:-
Charge a different battery and connect THAT to the dead battery using the guidelines below

OR
take the battery off the car (or disconnect it electrically from the car) then charge it, then disconnect the charger and reconnect the battery to the car

Here's the procedure to safely jump connect an external battery to your car

Be certain the vehicles are not in contact with each other.

Do not allow the cable clamps to touch each other.

Attach the positive cable to the positive terminal of the dead battery first. Then attach the other end of the positive cable to the good battery.

Attach the negative cable to the negative terminal of the good battery. Then attach the other end of the negative cable to the engine block. Do not attach a cable directly to the negative terminal of the dead battery.

Once the engine is started, carefully remove the cables in reverse order, again not allowing the clamps to touch.

Do not lean over the battery during the jumping process.

Make sure you connect to the ENGINE BLOCK (the other end of the battery neg lead is usually good)

DON'T JUST ATTACH TO SOMETHING SHINEY as the current will go through everything, sheet metal heats up rapidly melting cables along the way

 

[ProtoFJ]

Connecting another battery won't fry the ECU
What fries the ECU is connecting an electrical booster starter to the battery when it's still electrically connected to the car.

Errr as i have stated I HAVE seen this happen on several occasions so your assertion is wrong. Sorry

Attach the negative cable to the negative terminal of the good battery. Then attach the other end of the negative cable to the engine block away from the negative terminal. Do not attach a cable to the negative terminal of the dead battery.

Thought that was what I said.... ?

 

[Deckchair5]

Two batteries connected in parallel won't do anything.

See here http://www.handymanwire.com/articles/jumpingcar.html

 

[ProtoFJ]

Sorry
I don't mean to seem argumentative - it's just that I know from personal experience that this is a problem regardless of what theory says.

I used to help out with a recovery company and have seen this exact situation proabably as much as 10 times. (4 Ford Galaxies! they must be hypersensitive).
Well meaning passers by have tried to help people and given them a jump start, connected the two batteries terminal to terminal and cooked the ECU.

 

[Terminal]

I thought if you connect 2 batteries in parallel you get the same power (volts), but the current (amps) of the 2 batteries are added together.
If that is the case, the ecu would not take it. its usually the amps that does damage, not volts.

Been a long time since i did electronics, so i may be wrong.

 

[Deckchair5]

Exactly that, connecting two equal batteries in parallel means the voltage remains constant. Having two batteries in parallel is no different than putting in a heavy duty battery replacement. It doesn't matter what current the batteries are capable of, you could have a hundred batteries in parallel. as long as it's more than enough

Often the damage is already done to the ECU by someone trying to start using an electrical battery booster whilst starting. Sometimes ECUs are affected by low volts and that might be what happened to Galaxies, I don't know.

It's bad voltage that does the damage. ICs like steady voltage, no heat and no vibration

Look in the Stilo Manual for an exact carbon copy of the procedure mentioned earlier of how to jump start the Stilo

 

[StiloBoy]

Sounds like pish to me, i mean if the ECU was fried would your car start, would your car happily inform you that it had a fault.... nah. Sounds like the garage is trying to fleese you.

 

[FiatExpert]

Stilos have an ecu update for a eeprom error in the ecu which is logged by the computer.If the ecu was fried the would not start or that what i would of thought, but if is says "eeprom Fault"-Replace ecu, thens theres an update from fiat...

 

[T14086]

Use a pulse battery charger,if you haven't get it charged by Fiat dealer as they have one,well should have as Stilos,Galaxies,C-max use them & not normally run of mill charger.
Jump start a flat battery runs risk of destroying ECU I have seen in happen infront of me(normally by thick salesmen)many times even on new unregistered cars.

 

[Deckchair5]

Use a pulse battery charger,if you haven't get it charged by Fiat dealer as they have one,well should have as Stilos,Galaxies,C-max use them & not normally run of mill charger.
Jump start a flat battery runs risk of destroying ECU I have seen in happen infront of me(normally by thick salesmen)many times even on new unregistered cars.

What were the car salesmen using?
Starting car with a car battery/starter booster connected to battery? -fried ECU
Starting car with another good car with engine running and jump leads across to battery? -fried ECU. Want chips with that?

A pulse battery charger is just a more intelligent battery charger in that it checks the voltage of the battery at intervals whilst charging. It's still putting out a very dirty ie unsmoothed voltage. If you turn on the ignition- frying tonight- with mushy peas

After charging, a battery can be putting out an over high voltage for quite a few minutes until it stabilises. -turn ignition on- fried and battered

 

[HP]

If it's any help, a Ford mechanic told me once that you can fry the ecu on the car with the healthy battery if you don't follow the instructions for jump starting. Some people insist on revving the nuts off the car during jump starting, and the voltage flashes you get apparently can kill the electronic components on the car. Or cars.

 

[Shunter]

If these ECU's are so delicate then maybe its time we went back to good old contact breakers in distributors.

BTW I have an emergency start kit in the boot which connects to the flat battery terminals but will not supply any power unless the "flat battery" has at least 1.5 volts in it and have used it start my daughter's Zafira and a neighbour's Ulysee and neither vehicle has displayed any ECU problems

 

[T14086]

Reason for using pulse (or smart) charger is because of the type of battery in the car (lead acid) as I said most stillos use this battery (like fords) if you dont use pulse charger you wont charge battery properly.Pulse chargers are vital to cure alot of stilo 'ghost' electrical faults that dissapear after proper charging! Pulse chargers also 'revive' this type of battery to full state of health,normally done overnight.

Reason we use ECU's/pCM's etc is because of fuel emissions plus added benefit of tighter fuel metering/sparking.

 

[Deckchair5]

Reason for using pulse (or smart) charger is because of the type of battery in the car (lead acid) as I said most stillos use this battery

What do you mean? Almost all cars use lead /acid batteries. What's special about a Stilo battery?

A pulse charger can no more "revive" a battery than any other battery charger. Despite claims of the charger manufacturers, there is no proof that pulse chargers work any better than constant voltage chargers

A pulse charger is more intelligent in that it reads the battery voltage every now and again but that's about it

Ghost errors are often caused by a low battery but the cure is a recharge or a new battery

 

[T14086]

A pulse charger must be used with Lead cacium batteries,prefably overnight to 'revive' it.A normal battery charger will damage it (too much current) possibly buckling the plates,ok for short term measure but battery will need recharging again soon after (more 'ghost' electrical errors) assuming it has not been damaged.

 

[Stilo_ste]

I think the moral of the story is not to let your battery go flat. Therefore you won't have any charge problems. Keep on driving.



Just for the record, I fail to see how fitting an additional battery (of the same voltage and connected correctly) could damage ECMs etc. Any hoo.............

 

[Alex]

Slightly off topic I know, but it surprises me that car manufacturers do not (maybe they do, but it appears they don't) use voltage regulators on sensative electronic components to guard against voltage peaks, em noise and vibrations. Even if you distroy the regulator, its going to be less expensive than a new ECU (except manufacturers will make sure they're not, but powersupply design is relatively well established and third party units would undoubtedly be available)