Okay, if all the components stop working at the same time, they must all share something in common, ground? Was the car ever repainted? ground? could be a short intermittently between the control modules bring down the network,

and it would the tech out when you bring the car in when it's actually acting up.

 

Sad but true, diagnosis is done on an hourly basis. Some problems can be seemingly complex and simple to find, and sometimes the easy appearing ones are extremely time consuming. If the tech is using electrical diagrams properly and has a great understanding of the system operation it can still take many hours.

Imagine a light in your home quits working, that is an ultra simple circuit in most cases, goes from breaker panel to switch, then to the light...Exactly where the problem is is a mystery in the beginning, power ok to the switch and through the switch, that still leaves the lamp, the fixture, and all the wire section in between, if it's a break in the wire, do you rip out walls and replace the whole thing or do you look for the precise spot? The car is too complex to begin just running new wires, so the rules change.

Replacing any part on the Lex is expensive so you want a solid diagnosis, not just parts thrown at it. The LS430 has many multiplex modules that transmit information from one location to another, it's not an impossible, but a possibly difficult diagnosis. Hopefully the tech is competent, but that is really luck of the draw, depending on the person mainly.

I just finished a call to check a car for a shop here today, they said the car quit running and had good fuel pressure and had lost spark, I verify everything myself to be sure and guess what, I found the polar opposite to be true, spark is fine and there is no fuel pressure, I checked the amp draw of the fuel pump and it is 1/2 amp when a good pump will draw around 5 amps. That still does not confirm a bad pump though, wire integrity and connector flaws could cause the same, My final check was to put a jumper in place of the fuel pump and retest the draw to verify the wires are ok, that is a %100 certain diagnosis, not a guess. Maybe you have someone like guy that called me today working on it, or maybe you have someone following a logical path like I use. It is purely dumb luck unless you have firsthand knowledge of their capabilities. One wrong step in a diagnosis can lead them down a wrong path and who knows when they realize it??

Most of this has been random rambling from me, It is annoying that there are many incompetents in all lines of work, dealers have access to the best information and the most current scan tools. That does not guarantee the fastest, most accurate diagnosis, the difference is the individual. Best description for the idiots that fall into shops sometimes and have no clue, and I've had to work in the same spaces with them at times...."You can put a cat in an oven, but that does not make it a damn biscuit!"

Most competent technicians have come up through dealerships at some point, that is where the most information is available to them. There are still morons that came from the shallow end of the gene pool everywhere.

It could be worse, could be in the medical field, diagnostic tests performed until they identify problem, MAYBE it's accurate, possibly you get exploratory surgery, maybe you die from "complications", and someone still has to pay regardless of end result.

 

you are not alone, I have similar but different issues. My volume goes up and down as it wishes, The horn works intermittently, The steering wheel volume control stops working. this haves every day i drive. its so annoying. I am considering selling this UL to get a different more simple trim.