Ecu Fried After Jump-Start Due To Wrong Polarity

[praneetsrivastav]

Car Details

2004 Grand Voyager LX

2.8 CRD

Automatic transmission

 

Day 1

Someone helping my wife jump started the car with wrong polarity (Assumed due to current car behavior ). The car went fine for a mile then suddenly ABS light came on, then Battery light, then other random dash lights, speedometer started going crazy and then gears display went off and car stopped. after that it won't start . so jump started again  and again same story.

 

Day 2

took the battery out assuming it not getting enough charge to crank the engine.charged it for 1 hour and then put it back again. car started fine and drove for longer this time but then after few mins same behavior as above. after reading some posts it was suggested that leave the car without battery for few hours and try with fully charged battery. So I took the battery out and charged it fully using a wall battery charger.

 

Day 3

I have put the fully charged battery in the car and drove for 15 mins (2 miles) and it behaving as normal so far.

 

I have checked the fuses. everything seems to be fine there.

 

Now the questions are

-is there a way to check if my ECU is fried

-is my fully charged battery is hiding the any potential problem ?

 

any pointers would be appreciated.

[mikebh8]

Hi, to me it sounds the alternator is gone.

It happened once on a L200, but I put the battery the other way around...more or less the same thing.

If you have a multimeter, on DC with the engine idling, you should get around 14 volts.

You probably think that if it would be the alternator you will have the battery light coming on the dash, not always.

 

Hope it helps.

[Clutchnut]

Probably a charging issue, may also be the battery. That's the starting point. Not only do you want to check the charge rate, but first you will want to check the drop when cranking it over. If it drops too low then the battery is most likely on its last legs. And then if the charge rate is too high or low then that is another issue to resolve. If you cook the ecu, it tends to be terminal. And it is battery season after all.

[praneetsrivastav]

Thanks for the reply. I think it's alternator as i was able to jump start the car and when I removed battery connection the car stopped. Also i put the fully charged battery this morning drove for 10 mins and parked the car.in the eveing it was showing 11.9 in idle and 11.6 with engine on. I was only able to start using fully charged battery twice.

 

So assuming it's alternator replacement. Any idea what should be the fair cost for it.

[mikebh8]

They can be fixed, it worth taking to a local repair shop, I sometimes pay £10.

If is just the alternator regulator or brushes. Plus for wrong polarity more than likely the regulator is gone as that is the entry point of the current.

Otherwise between 80 and 160.

But again if yours is original (usually Bosch) try fixing it first.

Edited November 30, 2017 by mikebh8

[praneetsrivastav]

So called the mechanic and he said its not alternator (as per his OBD diagnostic tool its pumping over 14V but when I used the multi-meter on battery terminal it was showing 11.9 with engine on). he asked me to the replace the battery so I called Motarland (they are Chrysler expert) and bought exide eb741 for 95 gbp. I put the new battery car started fine first time and few times afterwords. and i drove for 50  miles and then same battery /ABS light came on and car won't start again with new battery. and once is recharged the battery i can again drive for 50 miles before symptoms starts again..

 

so after reading about buttonmod in increse the  charging temp. I did mod yesterday. also charged the new battery so it was giving 13v without engine on. when I started the engine with Buttonmod  it dropped to 12.7 and stayed at that even when I drove around. I am kind of sure now that battery is being undercharged  and Buttonmod  does not work for some reason.

 

here  is exact step  i took for buttonmod.

1. bought 22K resister  from maplin.
2. found the batter temp sensor wire 
3. between blue and brown, i cut the brown one.
4. added the resister each end to each end of cut wire. (see image)
5. taped it back.

 

am I doing anything wrong? is there a way to check resister if I got the correct one.

[mikebh8]

First: with the engine on, and no charging, no decent mechanic would suggest to replace the battery.

I would check the alternator, probably someplace else. With the engine running remove the battery, if the engine stops there is no charge. Also, if his software shows 14 something volts and on your multimeter 11.9, and if the software is right, it means the leads from the alternator to the battery are damaged.

Check with your multimeter, at the alternator( there is a 13mm nut at the side/top) and against the body of the car, see what reading you get.

For the resistor to check it's value, please look at the link below

 

 

https://www.google.co.uk/search?q=resistor+colour+code+chart&oq=resistor+code+colour&aqs=chrome.1.69i57j0l3.5802j0j7&sourceid=chrome-mobile&ie=UTF-8#imgrc=fKPKoho7ClunYM:

 

I never done the so called "buttonmod", where you got the info should specify what size you need.

 

Hope it helps.

[praneetsrivastav]

Thanks for the pointers mikebh8. I checked the voltage at alternator nut and its showing 11.9 v which is consistent with what was showing at the battery terminals with car on. When i switched off the car. It was showing 12.2 at nut and at the battery terminals. This also explains why the button mod did not work.

 

Does this proof enough to order an alternator or is there a chance it could be ecu. the garage is asking for 450 for alternator if they order it. I can get it for less than 100 online.

Edited December 7, 2017 by praneetsrivastav

[bignev]

Yep pretty damn certain it's alternator as mike said, from the earlier info too. If the voltage didn't change with it running.

 

My petrol wasn't bad at all to swap, getting the belt back on by myself was a sod!

[praneetsrivastav]

Wow bignev you must be handy with tools. I have been surfing through youtube to gather courage to do it myself. All the videos are of 3.3 ltr where the driver side wheel need to come off for alternator removal but when i looked my car 2.8 crd ,alternator is next to the engine on top.

So that's relif. Did you follow any instructions or video. Any tips on how to get the belt off and on?

Edited December 8, 2017 by praneetsrivastav

[mikebh8]

Hi, you just push towards the dashboard the accessories belt pully( I think it is a 16mm...I recently worked on it but I can't remember) and take off the belt.

Once the alternator's bolts are loose you have to wiggle the alternator back and forth and it will come out.

Pay attention when the belt is back on that is in place well on all the pullies.

If you forget how it was, make a drawing on a piece of paper( on Chrysler there is usually a diagram on top of the radiator under the bonnet)

 

Most important, remove the battery terminals while working on it.

 

Hope it helps.

[QinteQ]

Edit ref bignev

 

Edited December 9, 2017 by QinteQ

[bignev]

Blooming heck pal you must be more tired than me - he put a new one on as well as the fully charged unit.

[praneetsrivastav]

well I did it :-) well chuffed. Thanks for help guys. It wasn't as difficult as i thought. Garage quoted me 450 for the part+100 labor to replace the alternator. I ordered this one for 99 delivered from ebay. No garage was willing to put customer provided parts. so I decided to do it myself. and after succesfully replacing the alternator i am getting 14.6 v  (with buttonmod) from it to the battery. problem solved :-)

 

 

I will list steps here for anyone else in  my situation.

 

Prerequisite

- Good socket set . (cheap ones will be destroyed as bolts holding the alternator are quite solid. after breaking 2 cheap ones i had ,i bought this one from halfords .

- Camera to record steps so that if you forget anything you can see it back ( I might upload my version)

- a long wrench to hold the tensioner in place

 

Steps

1. Remove the negative battery terminal
2. remove the black big air chamber by removing a bolt and two jubilee clips holding the hose connection.
3. once the air chamber is out. you can see 2 bottom nuts which needs removing but hold on.
4. now see the location on tensioner in your diagram for your car next to your radiators.
5. put the long wrench on the tensioner and push it back towards the dash.
6. then belt  will loosen and you can take the belt off alternator. 
7. now you can  secure the wrench in same place by resting it on another wrench or bat in horizontal position by creating T like structure. (this saved me hassle of re doing the whole belt.)
8. Remove the 13 mm bolt connecting battery to alternator
9. Remove the Clip connection 
10. once belt if off  unbolt the top plate by removing 3 bolts.
11. once the top plate is off remove bottom 2 long bolts.
12. now use a pry bar or hammer with pry ending to wiggle alternator out.
13. Follow the reverse process to fit the new one.

Edited December 12, 2017 by praneetsrivastav