ECU problems?

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steviewonder
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ECU problems?

#1 Post by steviewonder » Mon Jul 18, 2016 8:32 pm

I have an '02 Astra with a Bigas system I fitted a couple of years ago, which until today has been relatively drama free!

The problem I have now is that it won't switch over to gas and the changeover switch is completely unresponsive. Only the petrol LED lights up and it stays lit constantly, even when the ignition is off and the car has been left for several hours.

So far I have tried disconnecting the battery for a while which didn't help, also I have tried to connect to a PC but get the message that the currently connected ECU is not compatible.

Does this sound like a dead ECU? Is there anything else I could try?

Any help much appreciated!

Brian_H
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Re: ECU problems?

#2 Post by Brian_H » Mon Jul 18, 2016 8:42 pm

Check you actually have 12v on both of the feeds to the ECU first - the one from the injectors and the one from the battery. It wouldn't be a bad idea to check the fuses are actually making good contact inside holders as well - take them out and look inside the holder (sometimes they will corrode over time if moisture gets into them, and can look ok from outside). It wouldn't be a bad idea to also check the plug going to the ecu hasn't come loose at the same time, It sounds like its seeing something on the end of the comms cable given that its showing not compatible, though this may just be an unhelpful message from the bigas software.

LPGC
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Re: ECU problems?

#3 Post by LPGC » Mon Jul 18, 2016 9:35 pm

Something would be amiss even if the red/white ignition(injector) live wire wasn't connected properly... The amber light shouldn't be on all the time.
Would check wiring first as Brian says. Presuming good lives and earth the next step would be trying another ECU/switch - far easier if you have them on the shelf of course!
Seen similar comms symptoms when incorrect firmware has been uploaded. Also when ECU has been jetwashed...

Simon
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steviewonder
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Re: ECU problems?

#4 Post by steviewonder » Tue Jul 19, 2016 2:39 pm

Thanks for the replies. Came out this morning and petrol LED was still on. I checked power/fuse/earths etc and everything was as it should be.

The laptop connects to the ECU when the switch is disconnected, albeit with everything set to default and no option to change anything.

I'll try a replacement anyway but is the changeover switch really such an integral part of the system? Are they known to go faulty?

Thanks again

Brian_H
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Re: ECU problems?

#5 Post by Brian_H » Tue Jul 19, 2016 7:00 pm

There is definitely more to the switch than just the leds and switch itself in most systems.

Being able to connect without the switch sounds like it could be a good sign though.

LPGC
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Re: ECU problems?

#6 Post by LPGC » Sat Jul 23, 2016 7:45 pm

Yes the switch really is that important... Probably didn't have to be designed that way but without the switch the ECU probably won't switch on properly, or at least won't see some inputs such as rpm, maybe vacuum, temps and gas pressure.

Agreed with Brian, looking likely just the switch.

Simon
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steviewonder
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Re: ECU problems?

#7 Post by steviewonder » Mon Jul 25, 2016 8:08 pm

Tried new switch to no avail. Also disconnected sensors etc one by one to see if the petrol LED would go out with the ignition off, but no joy.

Wiring still checks out ok so now looking at replacing ECU

LPGC
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Re: ECU problems?

#8 Post by LPGC » Tue Jul 26, 2016 12:18 pm

If you hadn't said you'd fitted it a few years ago (hadn't assumed it had worked properly since), I'd be saying another thing that can cause very similar symptoms is if petrol injector break wiring is connected to the + side of petrol injector(s) instead of the negative side. The same would occur if a petrol injector coil was shorted (but then it wouldn't run properly on petrol). But assuming it has run OK on LPG and still runs OK on petrol now, yes it looks like an ECU swap should be the next step.

Simon
Full time LPG installer
Servicing / Diagnostics / Repairs to all systems / DIY conversion kits supplied with thorough tech support
Mid Yorkshire
2 miles A1, 8 miles M62,
http://www.Lpgc.co.uk
Twitter https://twitter.com/AutogasSimon
07816237240

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