Bigas Sequential GIS - ECU board Diagram? (Burnt resistors)

[abu-bakr]

Hi folks,

Short story:
* Bigas GIS Ecu - semi conductor?? & Resistor burnt out
* I Need a map or diagram of board electronics to see codes of electronic that needs replacing (mine are carbonised)
* Pics of mine attached

Long Story:
I have had 5-6 cars on LPG. Currently its an old E38 BMW 730i V8 (1994 new shape). It has a bigas GIS system on it.

Either the clown who fitted the system or another clown who messed with it after, shoved the excess cable that goes
to the fuel level/lpg petrol switch under the dash around the steering column.. you can guess what happens next!
So a while back I was turning a corner and the cable tangled itself around the steering column and was duly ripped apart. After
I had someone repair the cable (a someone who simply joined some of the broken bits of wire back together until the switch
lit up and the system worked (but did not replace the cable and I didn't think about it either (what a set of clowns)).
After this the ECU board has stopped working and found to have a '4 pin semiconductor' (i'm assuming) thingamajig and a 'resistor'
burnt out. I have since borrowed a Zavoli ECU which is based on similar AEB electronics and runs the system but since I have
different injectors than what the borrowed ecu can handle it doesn't run very well.
The Zavoli ecu is also beginning to show signs of excessive heat around the same '4 pin' thingamajig (but I can't read the numbers on it).

The system sometimes will run (on the untuned Zavoli ecu) for a long while (10 miles+), while other times it will simply keep switching
back to petrol and giving error bleeps (either every mile or so, but usually as soon as switched over to gas it switches back and bleeps)
this was the same on the old bigas ecu that was tuned for this car and the same with the zavoli which is miles out of tune.

Two questions:
* I'm guessing I should replace the cable to the switch?
* Could it be something else causing these particular electronics to superheat?

My main request is for the Bigas GIS Ecu board diagram - Thanks in advance for your time fellas

[rossko]

* I'm guessing I should replace the cable to the switch?

No reason to, if it is repaired properly ; it's only 4 wires.

* Could it be something else causing these particular electronics to superheat?

Lots of potential for shorts elsewhere in the wiring too, wiring to tank can be vulnerable.

My main request is for the Bigas GIS Ecu board diagram

You'd be lucky. There are three or four different versions as well,

[abu-bakr]

* I'm guessing I should replace the cable to the switch?

No reason to, if it is repaired properly ; it's only 4 wires.

* Could it be something else causing these particular electronics to superheat?

Lots of potential for shorts elsewhere in the wiring too, wiring to tank can be vulnerable.

My main request is for the Bigas GIS Ecu board diagram

You'd be lucky. There are three or four different versions as well,

* That's just it, it prob wasn't, i've already found one unsheathed black wire touching clean metal (I have temporarily taped over this)

* I see, so the electrician should be able to check for these easy enough?? or not?

* a new bigas ecu is over £300 and I can't find any second hand ones. What else could I do?

[Gilbertd]

It's not easy to identify the burnt components because somebody has put big red crosses on them but the 4 legged beastie is almost certainly a switching transistor (the fat leg at the top being the heatsink), the resistor could be anything, the ones next to it appear to be 1k Ohms and 120 Ohms and the bit to the left looks like it once was a rectifier (big diode). If there are signs that the other ECU you have is getting warm, it might be worth checking the state of the electrolytic capacitors. They have that burgundy coloured exterior on them which suggests they could be Rubicon brand. Rubicon caps are known to fail after only a few years, look for any bulging of the top or signs of leakage.

Without a diagram or being able to trace the circuit to see what they are connected to, the presence of a switching transistor suggests that this may be connected with the output although they would usually drive a relay to do the actual switching of the solenoids so a short shouldn't affect them. In saying that you have two switching transistors but only one relay so it may be that one circuit switches directly and is the one that has been overloaded.

There are very few people around these days that are either capable or prepared to fault down to component level. Surface mount devices have made repair much more difficult than it used to be. It can be done but needs either specialist soldering equipment or a very fine soldering iron and a big magnifying glass (which is what I use with limited success).

[alexf2828-2]

only thing I can think of is borrow the same ECU from somewhere to get the component numbers/resistor value-but as said would be difficult to change the components anyway as it is SMD

[abu-bakr]

* Very large pictures available here http://www.thecarsupermarket.net/galler ... hp/v/new4/
Click to enlarge then click the image again to supersize. http://www.thecarsupermarket.net/galler ... ewsIndex=1 <-- HERE is a good picture

* I think I may be able to find another similar ECU that a friend has on his car if it is easier. I will update on how I get on with this.

* SMD?

* if its the 470uF caps you are referring to then you're right! - One seems to have bulged out to the side (and I have loads spare from attempts to repair LCD computer screens but not managed to fix any! )

* Big magnifying glass... Maplins?

* I could be very adventurous and try to email Bigas in Italy/UK and ask for a component map?!

[Gilbertd]

* Very large pictures available here http://www.thecarsupermarket.net/galler ... hp/v/new4/
Click to enlarge then click the image again to supersize. http://www.thecarsupermarket.net/galler ... ewsIndex=1 <-- HERE is a good picture

That's useful and confirms what I'd managed to make out from the smaller one.

* I think I may be able to find another similar ECU that a friend has on his car if it is easier. I will update on how I get on with this.

If you can and it is possible to identify what the burnt components are, then it should be possible to repair.

* SMD?

Surface Mount Devices rather than wired components. Instead of having wires that poke through the circuit board and are soldered on the underside, they are soldered to tiny pads on the surface of the board.

* if its the 470uF caps you are referring to then you're right! - One seems to have bulged out to the side (and I have loads spare from attempts to repair LCD computer screens but not managed to fix any! :P)

Only ever replace with brand new, not reclaimed ones, if they haven't failed already, will very soon. Be careful though as the board is plated through double sided board and too much heat will cause the tracks to lift. I would suspect that any caps removed from a dead LCD display will be the reason the LCD was dead in the first place....

* Big magnifying glass... Maplins?

Maybe, the one I've got is on a cantilever stand with a ring lamp around around it so you've got decent illumination too.

* I could be very adventurous and try to email Bigas in Italy/UK and ask for a component map?!

If they will supply you with a circuit diagram that would be ideal but they may not even have onbe themselves. Bigas use an AEB manufactured ECU so it may be a big secret to Bigas too!

[abu-bakr]

* if its the 470uF caps you are referring to then you're right! - One seems to have bulged out to the side (and I have loads spare from attempts to repair LCD computer screens but not managed to fix any! )

Only ever replace with brand new, not reclaimed ones, if they haven't failed already, will very soon. Be careful though as the board is plated through double sided board and too much heat will cause the tracks to lift. I would suspect that any caps removed from a dead LCD display will be the reason the LCD was dead in the first place....

Yeah the repair didn't work so I now have a packet full of new caps spare!

* I could be very adventurous and try to email Bigas in Italy/UK and ask for a component map?!

If they will supply you with a circuit diagram that would be ideal but they may not even have onbe themselves. Bigas use an AEB manufactured ECU so it may be a big secret to Bigas too!

Thanks for your information