Problems With Satnav Unit On 2002 Rx300

[Mark Barrett]

Guys

Apologies for the long post, but need to kinda explain where I am with this in order to ask my questions at the end. Also apologies as I have also posted this in the Electronics section to try and reach as many poeple as possible.

I have an RX300 SE Navigation (series 1 2002).

A few weeks ago the Boot mounted DVD unit for the SatNav expired - I am pretty sure it was due to a careless valeter spilling chemicals on it, but as I didn't use the navigation for a few weeks afterwards I can't prove anything) - Anyway I have taken the unit apart and the PCB has clearly suffered water damage and fried the PBC as a consequence. I was getting an "external unit is no connected" error when I tried to use navigation meaning that it couldn't see the unit as being there.

I have been lucky enough to source an alternative unit from eBay - came with Boot mounted DVD player, Audio head unit and screen and CD Multiplayer from glovebox.

I installed the new DVD player this afternoon, and it is now seeing the DVD unit (as it is asking to load disk etc), but after the "reading disk" cycle it then asks me to open the disk door and check the disk. This is as far as I have got.

So there are a number of reasons that I can think of for this, and I am looking for hints as to which way to go before I start ripping the car apart:

Are the headunit and DVD unit a matched pair? i.e. if I change one do I need to change both, or is the system not that clever? The DVD unit carries the same part number as my broken one, but didn't know if there was different software variants on the same part number?

Can I move up and down software versions by changing the disk? I now have a v1.02 and a v1.01 - should both work, or once you have moved up to a newer version you can't go back again? Audi for example, once you have gone up a version then it will throw an error if you go back down.

Does anyone know how many potential errors the "Check disk" message covers? Is it a simple case of the disk not being read due to being scratched, or could it be a wider range of problems like software imcompatibility? I didn't know how wide a range of errors the unit is capable of reporting.

I may be able to recover the DVD scratches, but I know the Lexus units are sensitibve to scratching, so I may be able to recover it on a PC to make a copy - I need to make it clear, this is NOT PIRACY, this is just making a second copy of a disk that I already own. I would be interested to know if these disks are successfully copyable - if people are uncomfortable replying in main page then a PM is fine.

Although I am competent electrically, I am not Lexus experienced, so any advice would be greatly appreciated

Thanks

Mark