Rear defroster is not working

JSabia85 · 10-11-2009, 08:47 PM

I have a 2002 Mitsubishi Galant and my rear defroster is not working. Here is what I have done to try and resolve the issue:

checked fuses... None blown, even replaced them

replaced the defroster relay

I even went as far as replacing the HVAC controls.

I checked the contacts at the rear defroster and when the deflated is turned on, the line receive 13.86 volts. When the defroster is turned off it drops down to around 5volts.

I thought it might be the rear window with a crack in the line but it's not because i have anoter galant in the glfanily and I ran a line from the defroster power like that connect to the window an ran it to the window that is not working. Turned on that galants and turned the defroster on and my window heated up in seconds.

So i know it's not the window.

I checked where the relay is plugged in and 2 pins on the relay get the same 13.86 v and the other 2 seemed to have only 0v. I'm not sure what the 0v are but I'm assuming it's the ground.

What else can I possibly Check to resolve this. I am completely stumped... It seems that everything is working because the window is receiving the power.

Also, on the other galant, it's a '99, the window voltage is 14.4, would the .6v really matter?

**octaneman** · 10-12-2009, 12:20 AM

Hi JSabia85

Use a DVOM to test the defogger switch for open circuit. When turning on the switch listen for the relay clicking.

post back your findings.

JSabia85 · 10-12-2009, 06:01 AM

The relay is fine, I even changed it, it clicks when I turn the switch on.

**octaneman** · 10-12-2009, 07:37 AM

There is a fusible link with 2 fuses to the system, a 7.5 amp and a 30 amp fuse.. You can check out the diagram at http://www.autozone.com/autozone/# .

JSabia85 · 10-12-2009, 06:06 PM

I finally figured out what was causing the defroster not work work. Finally after 2 years.

It ended up being the ground. It should have been the first thing to check.

The reason y I never caught it was because I never connected the ground of the multimeter to the ground of the defroster line, I kept grounding it to the chassis. SO I just decided to connect the positive of the multimeter to the + of the defroster line and then the negative of the multimeter to the ground of the defroster and I got NOTHING. SO I ran a wire from the ground of the defroster line and wired it to the chassis and it heated right up!

**octaneman** · 10-12-2009, 07:40 PM

Nice job :)

10-11-2009, 08:47 PM	#1 (permalink)
JSabia85 Registered User Join Date: Oct 2009 Posts: 10 OS: Windows 7	Rear defroster is not working I have a 2002 Mitsubishi Galant and my rear defroster is not working. Here is what I have done to try and resolve the issue: checked fuses... None blown, even replaced them replaced the defroster relay I even went as far as replacing the HVAC controls. I checked the contacts at the rear defroster and when the deflated is turned on, the line receive 13.86 volts. When the defroster is turned off it drops down to around 5volts. I thought it might be the rear window with a crack in the line but it's not because i have anoter galant in the glfanily and I ran a line from the defroster power like that connect to the window an ran it to the window that is not working. Turned on that galants and turned the defroster on and my window heated up in seconds. So i know it's not the window. I checked where the relay is plugged in and 2 pins on the relay get the same 13.86 v and the other 2 seemed to have only 0v. I'm not sure what the 0v are but I'm assuming it's the ground. What else can I possibly Check to resolve this. I am completely stumped... It seems that everything is working because the window is receiving the power. Also, on the other galant, it's a '99, the window voltage is 14.4, would the .6v really matter?

10-12-2009, 12:20 AM	#2 (permalink)
octaneman Mentor Home Support, Gearhead Automotive Center Join Date: May 2009 Posts: 545 OS: WINXP	Re: Rear defroster is not working Hi JSabia85 Use a DVOM to test the defogger switch for open circuit. When turning on the switch listen for the relay clicking. post back your findings. Last edited by octaneman; 10-12-2009 at 12:21 AM.

10-12-2009, 06:01 AM	#3 (permalink)
JSabia85 Registered User Join Date: Oct 2009 Posts: 10 OS: Windows 7	Re: Rear defroster is not working The relay is fine, I even changed it, it clicks when I turn the switch on.

10-12-2009, 07:37 AM	#4 (permalink)
octaneman Mentor Home Support, Gearhead Automotive Center Join Date: May 2009 Posts: 545 OS: WINXP	Re: Rear defroster is not working There is a fusible link with 2 fuses to the system, a 7.5 amp and a 30 amp fuse.. You can check out the diagram at http://www.autozone.com/autozone/# .

10-12-2009, 06:06 PM	#5 (permalink)
JSabia85 Registered User Join Date: Oct 2009 Posts: 10 OS: Windows 7	Re: Rear defroster is not working I finally figured out what was causing the defroster not work work. Finally after 2 years. It ended up being the ground. It should have been the first thing to check. The reason y I never caught it was because I never connected the ground of the multimeter to the ground of the defroster line, I kept grounding it to the chassis. SO I just decided to connect the positive of the multimeter to the + of the defroster line and then the negative of the multimeter to the ground of the defroster and I got NOTHING. SO I ran a wire from the ground of the defroster line and wired it to the chassis and it heated right up!

10-12-2009, 07:40 PM	#6 (permalink)
octaneman Mentor Home Support, Gearhead Automotive Center Join Date: May 2009 Posts: 545 OS: WINXP	Re: Rear defroster is not working Nice job :)