1997 Galaxy MPV Rear Window - No Voltage

Hi
The heated rear window on our Galaxy MPV stopped working, so we got the local glass company to check it out. The guy put a voltmeter across the
contacts on the lead at the window, and there was no voltage across them.
We asked a mechanic to take a look, and he did but can't find any reason why it's not working, it just isn't.
Is there anything peculiar with the rear window power supply on the Galaxy, or is it a common problem. Is it likely to be a break in the supply cable? If it is, how hard is it to replace it? Does it go through the roof, or under the floor?
Sorry to dive in with so many questions, but I'd be grateful for your help.
Thanks in advance.
Jason
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
JR wrote:

First thing I would do is look for a blown fuse.
I would think that there is a simple cable going from the switch to the window. So the places where there could be a problem would include:
1) The fuse. 2) The cable going from the fuse box to the switch. 3) The switch. 4) The timer mechanism. Usually there is a mechanism that shuts the circuit off after around 10 or 15 minutes. 5) The cable going to the rear window. 6) The ground from the defroster.
I'd start with 1 and go sequentially through these checking for voltage. When the voltage disappears, you should know what the problem is.
Jeff
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

Check the fuse with a test lamp or a voltmeter - ATO fuses like to fracture where the fuse element attaches to the prongs, and the center curved section won't LOOK blown. But if you look really close with a strong backlight you can see the opening.

This timer might be built into the switch, but is probably a little black box under the dash. Don't rule it out either way.
You can have power coming to the dash switch and going back to the black box, but if the black box is blown that's the stopping point. Black boxes love to have cold solder joints on circuit boards, or bad relay contacts.
Can also be an open chassis ground lead from the body ground to the black box - it can't run it's internal circuits without one either. You need the complete loop back to the battery...

There may be a stop at a body harness bulkhead plug/socket between the main dashboard harness and the smaller harness headed to the rear of the car. They can come unplugged.

And this is the one that nobody thinks to check - even if the +12V gets to the window, if it can't get to ground nothing happens.

And that's just how I'd do it too, methodical track-forward or track-back to where the power stops. Just thought I'd throw in a few more details.
--<< Bruce >>--
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Motorsforum.com is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here. All logos and trade names are the property of their respective owners.