I hope someone can help. Currently dreading the worst. I helped a family member jump start their car because their battery was flat, but they put the + and - on the wrong way on their car. This caused my car to stop working. The radio, doors, lights etc work but I can't start the engine. I have plugged the diagnostic device into the OBD port, but it came up with error and it can't link/connect with the computer. After to speaking to a few people, they think it could be ECU. Are there any suggestions that I could try to fix the problem before spending money? (E.g., seen stuff about charging the battery, checking the fuses)

Hello Luke, well the first thing to celebrate is you're still alive which is quite an achievement after shorting out two car batteries.

The chances are the ECU and GEM/BCM and possibly other modules have all had a heart attack and are now dead !! The replacing of various modules and the programming that's involved will  exceed the cost of your car.

Is your battery still OK ?

Generic code readers are not very good at this sort of problem. You need to get a laptop computer with FORScan software (it's free) and a modified ELM327 lead. If you are lucky it will be able to communicate with your car and at least tell you what the issues are.

FORScan: https://forscan.org/download.html

ELM327 lead: https://tunnelrat-electronics.fwscart.com/USB_Modified_with_switch_ELM327/p4541936_17045457.aspx

One last thing you can try. Disconnect your battery for 20 minutes. While the battery is disconnected turn the headlight switch to on, and then after waiting the 20 minutes reconnect and cross your fingers

Sounds terminal to me, my only suggestion and in my case i would remove the ecu and reveal if it is stripable, ie. can the pcb be removed ?

ecu is between the grill and battery i believe

For example my 2003 mk4 1.7 astra dti EDU failed which controls the spill valve / fuel pump - revealed to be possible to remove the pcb and an easy repair with just a bad solder joint....

My hope is that the ecu would be, and the primary front end regulator which is probably fed with 12v has been destroyed and therefore not supplying the mcu chip with it's 5v supply.

Saying that the OBD scanner is not communicating is a sign to me that the ecu is damaged, and i don't think an ecu from a breaker even if the same exact model can be used as each ecu flash is unique, sure the usual chaps here will confirm ?

Whilst not overly hopeful that this helps I am wondering if a fuse has blown somewhere eg in the power supply to the ecu etc.  I can’t help you on which fuses and where they are. 

4 minutes ago, isetta said:

Whilst not overly hopeful that this helps I am wondering if a fuse has blown somewhere eg in the power supply to the ecu etc.  I can’t help you on which fuses and where they are. 

I will shortly check the haynes manual wiring, and see if there's anything in there....

F16 3amp is engine management control unit fuse, you will get the worlds luckiest person award if it's just the fuse

Hi Trev, @fullwavebridge, I see the OP revisited here 47 minutes ago but obviously didn't care for our thoughts and suggestions since he made no comment. 🤔

Luke probably has more than one line of researching the suspect and i presume and will respond

I know what you mean though, there are many different posts with sometimes the answer and probable remedy to issues and the OP never follows up.

One i responded too, and actually offered to send a new wired connector to (i had to buy a pack from ebay - and used one !) and they didn't even bother to reply - i wouldn't even have asked for anything for it or the postage,,,, wow

I once years ago sent a bloke a couple of electronic components for his car with a known common fault (proton i think it was) which saved him over £400, he acknowledged receipt and i never heard anything again.....

I just enjoy the challenge not particulary the result

 

Apologies, I was logged on and then I had to return to work quickly. Really appreciate your responses. Currently reading through your comments. Some good suggestions here, and I'm discussing them with my mate who knows more about cars. Will definitely be trying some of these tomorrow. Keep the suggestions coming. Thank you so much!

Update!

Sorry I haven't been on here for a few days. The car is fixed!! It was a blown fuse. It was F16- 3A power supply circuit of injection system relay, injection computer. I would like to thank everyone who offered their advice and support. It was highly appreciated! Well done to those who said it could be a fuse, you were right (I guess I am the world's luckiest person lol)

I can imagine the elation when it started. 

1 hour ago, isetta said:

I can imagine the elation when it started. 

I was gobsmacked😂

You get the award.

The worlds luckiest man.    glad to hear it's sorted.