wgreene63

Just bought a used 2001 GS430 and the rear defroster is not working. The car has never had tint installed. Light on dash works, outside mirrors clear up but the rear window does not. I understand there is a relay for the rear defroster but I do not know where it is. Can someone please tell me where it is and if I can simply change it out with another relay to test it (maybe one in the same compartment) or do I need to buy another one to see if it is the problem? I found the connections to the defroster behind the rear passenger side C pillar and they are connected. All lines on the window are intact. I have found replacement relays online for around $50 but didn't want to order one until I knew how to replace it. I am mechanically inclined but do have a volt meter so I can do some simple troubleshooting but, any help would be appreciated.

sakataj

iTrader: (182)

the bolded text.....

go buy a cheap multimeter if you are mechanically inclined and can do the trouble shooting

wgreene63

Being mechanically inclined was stated so that everyone would understand that I'm not electrically inclined. Maybe someone would explain if I should check for voltage to the window or resistance across the defroster. I'm hopeful that this group is made up of more than people like yourself. Someone maybe willing to lend a hand. To, if you can understand the term, HELP.

Thanks.

sivikvtec

Do you hear the relay clicking from inside the car when you turn the defrost off/on? It sounds like it is coming from the front passenger side somewhere on my 99 GS400. It's pretty faint sounding, have your windows up, HVAC off, and radio off to hear it best...

I would assume that the mirrors and defroster wires were on the same circuit, switched by the same relay, but maybe not?

Can you unplug the defroster harness where it connects to send power to the rear window and measure voltage at the connector when you toggle the switch off and on? How many pins does that connector have, just 2?

wgreene63

I did check and I do hear the relay in the passenger compartment. Tomorrow I will check voltage at the connections to the defroster while the switch is on and report back if I get voltage and how much it is. There are two connections at the defroster. Thanks for the helpful response.

animalfarm

I have the same issue, completely unaware that there is a 2nd fuse box inside the car (1st under the hood, next to the battery), on the passenger side under the glove box, in the foot well.
The defogger/defroster relay is located there!