2004 Discovery II:
Replaced the xyz switch since someone had already been in the one that came with the car when we purchased it used. Installed it like rave instructions. Drove it down the road for about 15 miles everything was fine until the M&S lights started flashing. I turned it off and on the lights still blinking. I had to reset with a code reader and they went off. No codes were found in the scan. Drove home 15 miles later started flashing again. Same set up no codes but had to use code reader to reset the M & S blinking lights. I had the battery and the alternator tested everything was within spec 14.22 at idle and 13.1 with engine off. We are totally confused what to do next? Anyone experience this situation before.

Any help would be appreciated.

Bub

 

Sounds silly, but anytime the M&S lights flash on any Disco I've owned, it's because the battery needs a charge. If the weather is turning colder where you live, this would make even more sense. Throw it on a trickle charger overnight and see if that helps.

This is currently my fav to have with the Disco's tool kit: https://amzn.to/3Ohhhme

 

+1 for low battery voltage and cold cranking amps being the main cause for flashing M&S.

 

As I stated in my original post. The battery is fully charged and at idle it shows 14.4 and 12.99 with key off. I took apart the xyz switch to check for wear and one of the prongs tips was flat spotted. I had another xyz switch and replace the prong with one that was in great shape Re installed the switch and everything seemed to be fine. 4 miles down the road the m & s light started blinking again. This is very frustrating . Someone mentioned that the trans module possibly need replacement??? Any thoughts to help rectify this problem. This is my wifes' Land Rover and she loves it I can't let her drive it until this problem goes away.
Any help suggestions fixes ....

Thank You, Bub

 

You never said the battery was fully charged, only that the voltage was tested. Voltage can still be OK on a half-empty battery. Hopefully you get it figured out.

 

I did fail to mention that in my first post. I had it on a charge the night before.
I also changed out the original battery terminals as they were showing 13.4 at the positive side. When I installed the new post my volts jumped up to 14.4. The old one were corroded looking and I heard bad reviews on replacing the original terminals with similar ones from one of the vendors.

 

Edit: Wrong thread

 

I took my xyz switch apart and cleaned it, the s and m lights didn't come on again but it could also be a relay or fuse. Those lights coming on are so famous we call them the 3 amigos 😂🤣
​​​​​​.(sport,manual and Tcr.)

 

huh? not the same three amigos i've ever heard of.

 

If your voltage and grounds are all okay, check if AC condensate is dripping onto the XYZ switch.

I've dealt with M&S lights several times - first it was a bad ground leading to grounding of the parking brake cable (rubber covering melted into the interior cable/spring requiring replacement).

Then twice have had batteries fail after 1 yr of unpaved roads.

Most recently, I was clearing codes via OBD2 Torque App every 2-3 minutes to get the car out of limp-mode. The solution was to re-route the driver's AC condensate with some 1/2" hose shoved into the rubber opening above the transmission housing (zip-tie to the rigid cooler line).

I also have the same battery terminal connectors and no issues with them - make sure the battery posts are clean and have vaseline.