Off-Road Forums & Discussion Groups

Off-Road Forums & Discussion Groups (
-   Jeep-Short Wheelbase (
-   -   Rear defroster wiring on 88 yj? nead diagram. (

YJ_88 07-08-2001 03:34 AM

Rear defroster wiring on 88 yj? nead diagram.
Well I finally got tired of looking at all the wires that used to go to the computer and all the sensors for my old bbd. When I swapped in a mc2100 I just tie-wrapped all the wires onto the main harness with the idea that someday I might go back to the old system but I had come to the realization that that will never happen. I pulled the comp out and have cleaned all the wires out. While I was doing that I figuered I would get rid of those diagnostic plugs and the sol-vac relay. Then I got to the diode asembaly that is right next to the battery and was looking at it and my manuals and I cant figure out what its purpose is. It looks like a wire from the comp, the defroster and the a\c hook into it(I dont have a\c). My question is: why does the defrost circit need to be tided into this,what does it do. And can I run without it. My defroster never did work right and none of my manuals had a really good piture of what the complete defrost curcit looks like. Can somebody give me a hint. Thanks

88 YJ: TR upgrade and MC2100

Jaffer 07-08-2001 07:01 AM

Re: Rear defroster wiring?
While the rear wiper and washer circuits are direct switch to appliance connections, the defrost circuit is usually a switch to relay connection necessary to avoid the higher defrost current draw going directly through the defrost switch.


YJ_88 07-08-2001 02:08 PM

Re: Rear defroster wiring?
I knoiw there has to be a relay somewhere(probably under the dash) for the defrost or, like you said the switch would probably burn up. I am trying to figuer out what the diode assembly, that is right beside the battery, is for and why one wire from the defroster is tied into it. IT has one from the a/c and a black wire that hooks into the computer, these three are conected via a circiutboard to individual diodes. Then it has another wire from the comp and one from the sol-vac idles relay that are hooked to 1amp miro fuses in the circiut board. If anybody with a FSM could post or email me the complete circiut It would be a great help.

88 YJ:4.2 I6 TR upgrade and MC2100

glennCJ7 07-08-2001 11:17 PM

Re: Rear defroster wiring?
I just stripped out an 87 wagoneer wiring harness and installed it in a 82CJ7. I got pretty familar with the diagrams although not excatly alike I might be able to shead some light on your problem. the wires from the a/c and rear window defrestor that go to the diode go to the computor to incress the idle RPM to prevent drainning the battery.
You should be able to cut these out.

Build what I can, buy only what I must.[img]/wwwthreads_images/icons/crazy.gif[/img]
82CJ7 Rebuilding again.

YJ_88 07-09-2001 06:49 PM

Re: Rear defroster wiring?
Thanks, but I got got to looking at my chiltons manual very closely and I did fiquer it out. If the dfrost or ac is turned on it sends a signal to the sol-vac realy which in turn activates the solv-vac unit, raising the idle speed. I just forgot to post that I figured it out. But why couldn't they have used a normal relay why the dioide assembly.

88 YJ:4.2 I6 TR upgrade and MC2100

All times are GMT -5. The time now is 09:41 PM.

Powered by vBulletin® Copyright ©2000 - 2021, Jelsoft Enterprises Ltd.

User Alert System provided by Advanced User Tagging (Pro) - vBulletin Mods & Addons Copyright © 2021 DragonByte Technologies Ltd.
vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2021 DragonByte Technologies Ltd.
Copyright 1994-2009, VerticalScope Inc. // Off Road forums & discussion groups sitemap
side by side | atv | dirtbike | snowmobile | sandsport | competition | land use | Jeep | Toyota | Ford | GM

For the best viewing experience please update your browser to Google Chrome