Ok, hoping someone here can help with some ideas as I am out of them.

The vehicle in question is an 04 Disco 2.

Backstory: Picked this truck up very cheap a few weeks ago due to a couple of problems. Previous owner's mechanic had fashioned a push button starter on the dash to start the truck due to an unknown electrical issue. M & S lights on dash flashing sometimes while driving. Otherwise, truck is nice, low mileage, well maintained, etc. So in order to drive, turn the switch on, push button, truck fires up and runs good.

The push button start is wired through the SM relay in the under-hood fuse box.

Due to flashing M&S and gear selector, I figured the problem must lie in the BCU since I had run into that issue in a past Rover. I swapped a known-good ECU, BCU and IDM interior fuse box from a parts truck into this new truck. Removed wires for button start and replaced SM relay. Turned switch on, let them all sync up, but still no luck.

Removed ignition switch from parts truck and put it on the new truck, still no luck.

To verify, the ECU, BCU and IDM are all the exact same part number from the parts truck. The parts truck runs and drives but has body damage. I started and tested in the parts truck prior to removal, so I know they are good. I even swapped them back to the parts truck after trying them and let it sync with the switch on for 10 minutes and they worked again so I know my problem is elsewhere.

Any other ideas? No codes stored in modules since the battery had been unhooked to do everything. The red security light on the cluster is not on so I am not locked out. When you turn the key to try to start you can hear a few audible relay clicks under the dash but no power to the starter.

 

Flashing M+S is usually XYZ switch, which tells the truck which gear is selected. It sits on the transmission and gets filled with oil and debris and then fails. It's an expensive part to replace. If you haven't verified that your switch is good, I'd go that route before swapping out the computers and chasing down what sounds like some kind of immobilizer issue.

I'd also verify that your battery is good. Sometimes weak voltage can cause weird issues.

 

Check the starter connections and follow them back as well as testing the starter.

 

boston4,

thanks for reply.

Forgot to say that XYZ seems to be functioning correctly. With the new BCU, the M&S lights are not flashing anymore and the gear selector indicator on the dash is functioning correctly too.

 

I wonder if anyone with a Nanocom is close by?
That you could turn off and rule out the ignition immobilizer.

 

Where is the ignition immobilizer located?

Update on my end: I hooked up my scan tool (Autel DS708) Scanned for codes, nothing present other than a shutter valve fault in the ABS module. BUT, when I open tab that says security, the instrument cluster goes dead (gauges at 0 and all lights off) as well as the interior lights but the mileage reads "0". One single "0". When it does this, the truck will crank with the key and runs perfect.

Once I back out of the security tab, the cluster comes back to life, shows the mileage and lights back up. Once it does this, back to not starting with the key.

So it has to be security related so swapping "ignition immobilizer" as Sixpack said may solve it all.

 

Also, to add all of the following are tested and working properly:

battery
starter
XYZ switch

Where is the best place to buy Nanocom? I think I will have to suck it up and buy it owning several rovers

 

I am unsure of how all of it works, as I've never looked into it. Other than reading several posts on how it can cause issues, including preventing the truck from starting with the key.
It was recommended to turn off the immobilizer and superlock(unrelated, with it's own issues) with a Nanocom.
So I did.
Sorry, I'm no help.

 

Direct from their UK site
You can also rent one by mail from a forum member, it's in the stickies.
Hold on, I'll post a link to Nanocom's site.

 

Here you go

https://www.nanocom-diagnostics.com/