Much puzzlement! (remote fob mod)

[Raistlin]

Started doing the remote fob mod on a car.

Shorted each wire to earth to test that the BCU function was correct. One did nothing, the other blew the 30A fuel pump fuse :(

I then found out that "Lazy locking / venting" had not been enabled on the car concerned.

What is puzzling me is why, on what should be "earth to operate" lines, one should blow that fuse.

I can only assume that enabling "LL / LV" has something to do with it but I haven't a clue why.

Any ideas please chaps?

[Raistlin]

That'll be a big NO then :(

[Departed]

Can't see how it would.

Are you sure you have the right wires? You've done it before so I assume yes.

Where are you connecting? I can guess, but remind me.

[Raistlin]

Can't see how it would.

Are you sure you have the right wires? You've done it before so I assume yes.

Where are you connecting? I can guess, but remind me.


Yes - right connections. Double and triple checked by Steve and me.

BCU C0660 terminals 10 and 27.

[StevenWilliams]

sounds a little weird. Perhaps the switching is changed slightly with the T4 change. A bit like the backup sounder needs to be on the car for the powerwash to work.

[Raistlin]

sounds a little weird. Perhaps the switching is changed slightly with the T4 change. A bit like the backup sounder needs to be on the car for the powerwash to work.

That was the only thing I thought it could be Steven. It's not made clear in RAVE though which is very odd.

[Departed]

The function of those wires without lazy vent would not have anything to do with fuel pumps.

However C661 pin 10 is connected to fuse 30 but this is a 20A BCU supply, not fuel pumps. OK wire. C660 pin 10 is KN.

[Raistlin]

I've had another thought about this.

I don't know what caused the fuse to blow but I'm now certain it was the act of shorting either C0660 10 or 27 to earth.

Looking at it logically, if the car is an unknown quantity, you test for lazy locking and venting by operating the key in the driver's door lock. The function either works or it doesn't. There is certainly no record of doing that ever causing a fuse to blow in a car without the LL /LV function enabled and shorting the wires on C0660 10 and 27 to earth manually is exactly what happens when you use the key in the door lock.

So somehow or other, one of the lines must have been connected momentarily to the fuel pump circuit.

Indeed, we tried the "key in the door" test after having replaced the fuse and it didn't blow again.

So I'm now left wondering how the fuel pump supply could possibly have been inadvertently connected :shrug: