Picking up a clean clean lr3 with 130k miles on it tomorrow to tinker around with. Special programs off is displayed. I first intend to check the battery voltage and all other basic electrical voltage systems, seems like sometimes its voltage related from the searching i have done.
If nothing is found, where should i go from there?
Level sensors? how do I check them?
transfer case ecu?
I have done a search but found tons of different opposing information.

 

TR switch, brake switch, wiring/corrosion check....

 

What is TR switch?

 

Terrain Response switch...I guess "****" would have been a better descriptor.

 

Thanks!

 

Are there any dash lights? Lots of systems tie together, one can bring down another.

 

Just the message and the suspension fault light. Also message that states suspension normal ride height only or something like that. I can head the compressor running and also the suspension does not drop or sag down.

 

Well there ya go, suspension failure can take down the special programs. Get suspension sorted out and I bet you are good to go.

 

That makes sense. Any tips on where to start troubleshooting?

 

Codes. There are several sensors in the system and items read. For example, amperage draw of the compressor is read. Pulls too much power, assumes there is an issue. Also the reservoir air tank pressure is monitored. If it builds too slowly, fault. And the list goes one. The basics can probably be figured out without codes though. First thing will be a hard-reset of the vehicle when you get it (disconnect battery for a few minutes, make sure you power down the car and WAIT a couple minutes before disconnecting! - Lets the computers power down to a safe state). Then go from there.