I own an '06 CLK 350 and when the passenger seat heater button is depressed on the dash it does not light up. The seat heater does not turn on...

I am thinking the issue could be the switch in the dash but it could be wiringor the element.

Any suggestions on where to start my troubleshooting?

 

A failed seat heater pad can be indicated in sds short test. You can disconnect the connector at the bottom of the seat. Should be 4 pin(2 connectors clipped together), 2 blue/2 brn and test continuity between the blue and brown of each circuit. One is for the bottom cushion and the other is for the backrest. There will likely be high resistance or an open circuit in the faulty heater pad. This is a very difficult job to repair for the diy person.

 

Ask a upholstery seat to give you an estimate...might save you some money!

-mar-