2005 is250 jump start - wrong terminal

[Duffman]

Hi all,

I hope you can help.

Wife's Lexus had a flat so in my wisdom, I decided to jump it using my Mercedes. Stupidly, the Mercedes dealer at some point placed the red Battery cap on the negative terminal and the black on the positive. Not double checking, I inadvertently connected the terminals incorrectly and well.... you can guess the rest.

I checked the fuses under the bonnet... The fusible link was broken (it looked like 19 - Alternator 150amp). The car still started but the dashboard was lit up like a Christmas tree and the car was in limp mode. The central locking didn't work nor did the electric seats (I didn't test everything at this point).

Lexus wanted £130 for the fuse but then I found one for £30 off eBay. I replaced this yesterday and there was certainly some improvements. Car started but only the engine management light and VSC was on. Car is still in severe limp mode (barely revving). However, central locking and electric seats now working.

I have checked every single fuse under the bonnet (1 x box next to the battery) and the 2 fuse boxes beneath and either side of the dashboard. I haven't checked the relays yet as I need a multimeter but can't see how Noise Filter, Defog, GLW RLY2 (Fan no3 Diesel), Head LP, GLW RLY1 (Fan no1 Diesel) or Starter could be causing this.

Can anyone assist further in helping me diagnose and hopefully resolve.

Many thanks :)

 

 

[Texas]

If you haven't done so already after this mishap, do a soft re-set of the ECU to clear out the volatile memerory, do this by dis-connecting the Battery - ( Negative terminal ) for a short period of time ie 15-30 minutes to allow all residual current to disapate.

Note: unless you have electrically insulated Spanners ( I don't! ) always disconnect the - ( Negative Terminal ) first. There is a chance that if you disconnect the + ( Positive Terminal ) first with a metallic tool then that tool could inadvertently touch the surrounding metalwork of the vehicle and before you know it you are Arc Welding.

Paul M.

[madasahatter]

If that does not work you need somebody with a code reader. Have you checked fuses on drivers side behind the plastic cover.

If you know somebody with a code reader clear all faults and then restart the car. It could be the stored faults that are the problem. 

[Duffman]

Texas: Thank you... I've tried that but unfortunately it didn't work.

Madasahatter: A friend has a cheapo one from eBay. I will give that a go later today.

All the suggestions and more are welcomed.

Many thanks

[madasahatter]

The cheapo should clear the faults as long as engine management is on.

[Texas]

I might be dreaming it (won't be the first time) but I think someone has had this problem before on this forum ( can't find it right now as the search function is pants if you ask me! ) and leaving the Battery disconnected overnight might have made a difference, just another no-cost action to try.

paul m.

[Duffman]

51 minutes ago, Texas said:

I might be dreaming it (won't be the first time) but I think someone has had this problem before on this forum ( can't find it right now as the search function is pants if you ask me! ) and leaving the battery disconnected overnight might have made a difference, just another no-cost action to try.

paul m.

Hi Paul,

I couldn't find anything here using Google search but a few similar issues came up on US forums. I've so far exhausted everything although still researching.

I've disconnected the Battery again just now and will see if a few hours will allow the ECU to reset itself.

I'm hoping the ECU itself isn't damaged 

[Duffman]

All sorted now 

Found this weblink from our US cousins ...

https://www.clublexus.com/forums/is-2nd-gen-2006-2013/851600-engine-not-responsive-check-system-and-vsc-are-lit-after-replacing-fusible-link.html

It turns out there are 2 fuse boxs in the is250 which according to the manual is a type A and type B. The manual isn't clear as to whether the car has both or one ( I assumed the manual covered different models). I checked the second fuse box as per the above link and it was the exact same ETCS 10amp fuse. Replaced it and jobs a good one! 

Annoyingly, while I was replacing the linkable fuse yesterday, I didn't notice the second fuse box and assumed it was a air filter housing.

So the moral of the story... Don't buy a bleeding Mercedes!!!!! 

[madasahatter]

Well done you for finding that out.

[Texas]

Good result there then chap.

paul m.

[bobmc]

Glad you got sorted

And top marks for coming back and letting the community know how you fixed it ! Someone, sometime is bound to have the same problem and come looking for answers. 

 

 

[dougie175]

Great result thanks for sharing the info!