2008 dodge grand caravan rear defogger

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Forum Name: Vehicle Wiring Information & File Requests
Forum Discription: Request Car Alarm, Car Stereo, Cruise Control, Remote Starter, Navigation, Mobile Video, and Other Vehicle Specific Wiring Info, Manuals, Tech Tips
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=121739
Printed Date: May 14, 2025 at 2:52 AM

Topic: 2008 dodge grand caravan rear defogger

Posted By: nomaxtech
Subject: 2008 dodge grand caravan rear defogger
Date Posted: May 08, 2010 at 5:20 PM

Hi there,

I have a Viper 5601 alarm/remote starter in my van. I have connected a few things to the AUX wires for fun and figured I'd try to connected the rear defogger while I'm at it. The thing is...how do you do it? I have the actual true manufacturer service manuals to help me with anything I'd ever need to do but the rear defogger is on some CAN data bus. The manual describes it as (simplified):

When the rear defogger button is pressed, the AC/heater cluster sends a message on the CAN data bus to the totally integrated power module (fuse box under the hood) to turn on the button's backlite and the rear defogger.

I looked up the color codes for all of the wires connected here and sure enough, it's a data bus wire. So how can this be done? It's not a simple pulse or on/off, it's an actual binary message. Any ideas???

Thanks in advance.

~Jim

Replies:

Posted By: dankadad
Date Posted: May 16, 2010 at 11:48 AM

I'm looking for the same info for a 2010 Caravan. 2008 should be the same.

Can you email me a copy of the page that has the rear defogger circuit on it.

grannysapplepie@hotmail.com

thanks

-------------
bb

Posted By: awdeclipse
Date Posted: May 18, 2010 at 2:55 PM

Can you locate the Rear Defroster Relay (if it has one)? Or looking through the service manual, can you figure out where the rear defroster gets its power from? If you are unable to replicate the message sent from the defrost switch, you should be able to tie into the power being fed to the defrost grid controlled via a relay.