BSI

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Ceenine
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BSI

Post by Ceenine »

I need to replies the ECU on my C4. My second hand parts supplier has supplied me with the ECU, the fuse box located behind the glove box and the key circuit board. I understand that these items must be replaced as a unit and in the correct sequence. I understood that the fuse box to be installed was the under-bonnet unit which resides adjacent t to the ECU. Which is correct, under-bonnet or behind glove box? I need to make sure that I install the correct components.

Thankyou in advance
RichardW
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Re: BSI

Post by RichardW »

Hi

It's the one behind the glove box you need to replace. The underbonnet fuse box is not coded to the immobiliser. You need the transponder chip from the donor car to make it start - the remote locking function can be programmed without a Lexia after the car is running again. I don't think there's any particular sequence - battery off and change the ECU and BSI, and then battery on, and try and start it with the re-worked key. I suspect that this mod will make the car think it has a different VIN which might cause confusion if it is ever interrogated with a Lexia - and unless the spec of the donor car is identical, certain things may not work.
Richard W
Ceenine
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Re: BSI

Post by Ceenine »

Richard
Do I understand that the transponder chip is in the key fob - and thanks so much for your prompt reply
Don
BX
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Re: BSI

Post by BX »

If the original fault is with the under bonnet fuse box bm34 it can be changed on its own without any programming.
The one behind the glove box is the BSI.
If your BSI has an electrical/electronic fault rather than being corrupted then swap the EPROM chip (95040 or 912dg depending on BSI type) from your own BSI to the replacement. This means no key changes, no immobiliser problems and your odometer reading remains the same. Alternatively someone with an EPROM programmer can load a virgin file onto the replacement. You then program the replacement with the correct features for YOUR car.
Most TV-electronic repair shops would have the equipment to swap the chips.
The procedure for changing the engine ECU is similar to the BSI.
The antenna for the immobiliser transponder on a c4 is dumb.
Ceenine
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x 8

Re: BSI

Post by Ceenine »

BX
It is my ECU which has carked it (Aussie for stuffed). From your remarks it seems to be the solution to replace ECU and change over bit(s) on fusebox to retain distance data and key code. Some more detail on how everything interacts would be greatly appreciated to upgrade my knowledge base if for no other reason than I enjoy the challenge of knowing "the how and why".

In relation to the immobiliser comment, do you mean "dumb" as in poor functionality or cannot communicate very well.
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Re: BSI

Post by old-un77 »

I think Dumb in this context means that the antenna doesn't actually DO anything, until it senses that the key is turned in the ignition and the Immobiliser chip is in "talking" range.......
BX
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Re: BSI

Post by BX »

What I am saying is to change only the faulty unit and leave everything else alone. That way your Km remains correct on the odometer and the correct VIN is stored. In addition if you need to replace a key the pin remains the same.
Normally the easiest way to replace a faulty ECU with a second hand one is to clone the original onto the replacement. Most of the people offering chip tuning have the equipment to do this. All the memories from your original ECU are read and stored as files on a PC. These are then programmed into the replacement ECU making it an exact copy or clone of the original. It can be then plugged into the car and will work without doing anything else to the car. Alternatively the small EPROM chip can be swapped. The ECU can then be fitted to the car and the car will run but there is the possibility of the ECU throwing a tantrum about a checksum error or internal fault.
By "dumb" I meant having no intelligence. The antenna at the ignition switch is just a coil of wire. It is connected to the com 2000. The com 2000 is the light/indicator/wiper etc switch on the steering column. It does not analyse the immobiliser information but merely passes information over the can bus between the BSI and the transponder chip which is in the key. By the way the name "com 2000" comes from the French word for switch "commutateur"
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