190E Defroster Problem
 

Hey all:
I didn't think my defroster worked, so I bought a new switch and installed it. Now, when pushing the new defroster button, the switch doesn't become brighter as it should when the defroster is on. Any ideas? Thanks in advance.

Did you check the fuses?

Haasman

Yup. I even replaced most fuses just to make sure.

Makes me wonder if either the switch isn't contacting correctly to the plug on its back or a bad relay?

This is all presuming the switch light works .... have you tested it?

Haasman

The relay for the rear defroster however controls a lot of other functions that all work. Could a combination relay possibly not work for just one function. About the light, it turns on when the lights go on but does not get brighter when depressed as it should.

On my '88 190e the intermittent wipers did not work and the defrost only worked once in a while. Fixed it by pulling out the combination relay and lightly sanding each of the connections. Now both the wipers and the defrost work fine.

Night time illumination of defroster switch is fiber optic which is fed from an instrument panel light. Defroster ops indication is electrical. On the back of the switch, pin # 31 is the ground for the light, this ground may be connected to the hazard flasher switch ground wire. Feed back power to the switch from ( or to ) the combo relay is through pin# E and/or #A. A & E are not directly connected to the window element ( pin 87 or 07 is ). Combo relay pins #A & #E are wired to pins #A &#E on the switch. Check for voltage at the rear window element.