HI my 2008 freelander 2 the Abs pump is not working they wont £2,250 at land rover agents to replace I bought a second hand pump with matching numbers but when I fitted it the ABS lights went off but car would not start got a read out saying It doe's not recognize the ignition key I put the old pump back and the car started but the abs lights stayed on need help can't afford two buy new pump is there anything I could do ?

I don't know for sure but it almost sounds like you have to use JLR SDD software and marry the new abs pump to the system.

Days gone bye electrical stuff was hard wired, so you could replace a faulty unit with a good known one and it would work.

These days there are many blocks of information passed between units, each of these has it's own processor and so is therefore semi-independent of the main processor. So these units communicate via a bus system lets say 4 wires that replace a couple of dozen if everything was hard wired - less to break, cheaper to wire, more flexible if you don't get it right first time.

Now you could call all ABS pumps address 12 for example, and so every ABS pump would work plug and play. OR you could give each one a unique address (ABSxxxxxx7 for example), at this point you would need to program the other control units to look for ABSxxxxxx7 rather than ABSxxxxxx6. The first is sensible and allows anyone to work on the vehicle, the second forces you to go to an establishment with dealer level diagnostics and programming ability (both hardware and technician).
You don't have to guess which the motor manufacturers have done. Tangiers Orange - gone, missing her
Replaced by Ewok what a mistake - now a happy Disco Sport owner

Isn't it about time that a common system was used by all vehicle manufacturers, and plug and play enabled, suitably designed, units were allowed to be changed/added/removed from the car. (by the owner or semi skilled mechanic)

Hopefully, no special test equipment would be needed because it was all controlled via a sub function of the infotainment system.

If I can do it on my laptop, and for example, introduce a completely different printer, why not similar for my car.

My laptop also has diagnostic programs available which fixes most software faults and provides clear language answers to others.

Cars are getting increasingly complicated and need to be designed for easier maintenance, otherwise in the future I see dangerously botched up repairs to the electronic systems causing accidents. FL2 XS SD4 Auto 2010 2012-2017 (21k - 91k miles) (MY2011)
FL2 Metropolis SD4 Auto 2014 2017- (16k - 82k+ miles) (MY2015)
Metro in its 11th Year of (Extended) LR Warranty / Full LR Service History
(Expensive, but Trouble/Worry free - hopefully?)

Presumably the chassis number is stored in the ABS module as a security measure. You'll likely need to have the replacement ABS module configured to the vehicle, using SDD. Hyundai Ioniq 5 Ultimate. The family car.
2009 Rimini Red SE TD4. Gone.
2006 Tonga Green i6 HSE. Gone.
Audi A5 convertible, my daily driver.
1972 Hillman Avenger GT, the project.

Ian I think that you are coming at this from the wrong angle.

Car manufacturers are here to make a profit the end. The cars that they make are a source of revenue and they will use every trick in the book to maximise that revenue.

In days gone by they would use the safety card as a means to justify preventing "home mechanics" from repairing their own vehicles. Now they use the environmental card to even better effect. something as simple as changing the oil now cannot be done at home. You need to tell the car that the oil has been changed or it assumes that the oil is diluted and refuses to do DPF regens, destroying the very expensive DPF.

Speaking from bitter experience. On my old DS (2016) I did intermediate oil changes every 10k and told the car that the oil had been changed using a Foxwell diagnostics kit (£250). My newer DS (MY2019) will not communicate - bus has changed and there isn't a unit that will communicate for less than £2k, so despite being time served and having the filter and oil in the garage ready, I have to pay the dealer to change the oil in between regular services. Tangiers Orange - gone, missing her
Replaced by Ewok what a mistake - now a happy Disco Sport owner

Like others said, use dealer (like) tool(s) to "marry" the ABS module to the car.