Hi all,

Can anybody tell me the location of the pesky 5AS immobiliser/alarm module on a Libra? Is it hidden up under the dash?

I think mines misbehaving and preventing the car from starting (no fuel). I'd like to investigate wiring and understand how it links to the ECU.

Thanks for any advice

Steve

TBH it could be anywhere*, but the manual suggests putting it under the dash - if so i'd have a quick look in both footwells up under the dash, but more likely you need to take the dash top moulding off to find it.

* eg I put mine in a sealed box (along with other needed electronic stuff) on the engine bay bulkhead cos it suited my setup better.

Standard place to put it is under the dash, kind of central. It is a black box about 80mm by 50mm, 25mm thick with a grey multiplug. Fairly easy to take the dash top off but harder to get back on as it is hard to align the air vents for the demisters.

You should be able to hear it click when you operate the remote fob so put your ear on the dash and press the fob buttons a few times. On the donor car it operated the central locking, alarm and immobiliser but my Spyder doesn't have central locking or alarm so those wires are removed from the multiplug.

Based on the standard wiring it switches the earths from the fuel pump relay and one other circuit (I think the ignition coils). It also handshakes with the ECU and agrees a code for the next time. If the handshake code isn't accepted it'll start and run for about 5 seconds and then cut out and then won't restart. Even when armed it should still crank though. Assuming the V6 has a similar set up there should be a black box of relays mounted near to the ECU in the engine bay. From memory the fuel pump relay to 5AS wire is white/black (check!) and simply earthing that takes the 5AS out of that circuit so as long as the ignition is on the fuel pump should whirr until up to pressure and then stop until there is demand for fuel (engine running)

Thanks guys. I presume that as my car is a factory built V6 (and I was given a MG ZS/Rover45 Haynes manual), that the car will use the donor car's loom as below from manual?

Pretty sure that just takes out the handshaking function from the ecu. The 5AS still immobilises whatever circuits it is protecting. Having now looked at the MGF book my engine compartment loom is from it protects the fuel pump and the starter motor circuits. On mine the starter was never protected as the original builder wired it bypassing the 5AS but it was switching the fuel pump until I bypassed that. That just left it doing the handshake. I recently upgraded to a K-maps ECU and that had been set in the map to not need the handshake so the 5AS is now completely redundant in mine, don't even carry the fob now.
Assuming the V6 is similar that is what I'd advise - bypass everything you can! I would recommend some kind of anti theft device though otherwise your insurer might get upset. Mine came with a completely separate Toad immobiliser and that is still in place.

I would recommend putting an inertia switch back in though - if you do have an accident you don't really want the fuel pump still running! They don't seem to pop unnecessarily, I've had a couple of spins on track and ended up going over some bumpy infields and the inertia switch didn't let go.

The 5AS in my Libra is under the front clamshell on the passenger side inner wing.
Mine was also factory built.....