Trouble Shooting Rear Defogger

[rustbucket]

I figured what caused the heat is the connectors over the years may have corroded and high current through a weak connection caused heat. So I soldered the wires onto the PC board. I tested it and there was nothing hot.

[happydog500]

Originally Posted by rustbucket

I figured what caused the heat is the connectors over the years may have corroded and high current through a weak connection caused heat. So I soldered the wires onto the PC board. I tested it and there was nothing hot.

Makes science, mine was very corroded, but it was a lot of burnt corrosion.

[enslow]

Sorry to bring up an old thread, but I have a couple of valuable comments related to this.

First of all, great job Chris! I wish I had noticed this thread before. HotZ28 directed me to it.

I would reiterate ND4SP's comment to tape up the connectors. I would maybe slide on some more heat shrink over the exposed terminal ends, then mix up a batch of JBWeld to both hold the terminals together and provide a bit more electrical insulation.

When I took my module apart I noticed that the worst charring was on the terminals themselves. This indicates that the correct fix is not to change the module (unless it is actually defective as well), but to replace the terminals as you have.

Chris, if you have pictures showing insulation going right to the ends of the terminals, and a note indicating which terminal is for the rear defog and which one is for the antenna amplifier, I would recommend this thread be placed as a sticky. You have one of the most intelligent repairs I've seen so far and would have saved me from paying $90 for a new module (stuff in Canada always costs way more, usually because of shipping).

[happydog500]

After I fixed it, we didn't have very much weather where I needed to use it. I found out that the way I have it, when I used the defogger and radio it got a little static. I think the plug provides insulation. Going into winter, I think I'll get the plug since it's only $19.99. (after I get it running of course).

Thanks for the reminder.
Chris.

[enslow]

If you are getting static it is possible you have the terminals reversed. One terminal is gives power for the the antenna amplifier while the other terminal gives power for the heater grid. The power to the antenna module comes on only with the radio on. It's also possible the circuitry for the antenna module got fried.

[Jam88es99]

You probably blew the fuse for the rear window defrogger.

There's a relay on the A-pillar panel but no fuse in there for it.

Check under the hood in the relay maxifuse center to see if that one burned.

I don't find the antenna/defogger connector box on Rockauto.com or advanceautoparts.com.

You might get one from a junkyard.

I cleaned up the contacts on mine.

[enslow]

Just to update the defogger issue:

The connector seems to be the failure point. I've gone an ordered a replacement module for no reason at all. Unfortunately it's paid for and sent. I'll just keep it as a backup.

Rustbucket's solution seems to be the best. Solder the connections directly module. If you want convenience, buy a $5 connector (I used bullet style connectors) so I can remove the module from the car easily. I would avoid crimp connectors at all costs.

Chris, is your static on AM or FM? Unless I'm mistaken, the FM uses the heating grid for the antenna, while the AM uses a separate line on the top of the windshield.

[Tech II]

Have seen problems with the "ribbons" in the glass.....if you have the FM on, and then you turn the rear defogger on, and if you get static with the rear defogger on, chances are you have a break or breaks in one or more of the ribbons.........see this happen a lot because people throw things up on the rear deck and damage the ribbons.....all it takes is a scratch.....can hardly even see the break......on a cold morning, when the rear window is fogged or frosted, turn the defogger on, and see which ribbon isn't working....

Gm had a TSB, to roll a small ball of steel wool, and light lightly drag it across a broken ribbon....you will see a little spark when it jumbs the ribbon at the break on the wool....

Can be seen with a magnifying glass....

Can also be found with a voltmeter, also...

[imidazol97]

Originally Posted by Tech II

Can be seen with a magnifying glass....
Can also be found with a voltmeter, also...

Can also be seen by having someone run a flashlight over each ribbon on the inside while you look from the outside, or vice-versa. The light will show through the break or crack making it readily visible.

[enslow]

Originally Posted by imidazol97

Can also be seen by having someone run a flashlight over each ribbon on the inside while you look from the outside, or vice-versa. The light will show through the break or crack making it readily visible.

You can usually narrow down your search by using the defogger on a foggy window and observing the defogging pattern. Then use the above techniques on the grid lines that aren't working to find the exact break.

[enslow]

Update:
I soldered 14 guage wire to the module for the heater circuit (purple wire, closest to centre on module). I replaced the original conector with a weatherpack connector:

205_WPT-2-203.jpg

210_WPS-2-203.jpg

16 or 18 guage wire gets too hot. You must use at least 14 guage wire for the heater (purple) wire.

[Brandon455]

OK, thank you. What make it easier for me to work on cars is if I can go over it before I do it. This way it gives me more confidence. Plus I don't get into it and get stuck, with it all torn apart.
I did pull on it a little. Felt like the headliner was ripping. I kind of knew it was there, just my manual doesn't show it there.
The real thing that pisses me off is, the Offical GM Shop Manual says, in order to get that panel off, you need to take off the plastic around the window and the door trim. It also adds that to take off the door trim, you need to remove the rubber door seal.
I usually think GM knows what needs to be done. They wouldn't put in a manual something that's not true.

[enslow]

I just peel the soft vinyl trim away from the rear sail panel and pop the sail panel on top of the vinyl trim. On the pre-2000 Lesabres there are two push pins holding the sail panel in place. You can fairly easily reach in and pull the sail panel off. The push pins may remain in the holders, so you may have to replace them to the panel.

[HotZ28]

Composite trim removal tools are a handy item to have (and cheap) for removing the panel push pins without damaging the pins, or panel. Click Here

[ncsparky1]

Any idea what the connectors are called and where you get them for the Radio antenna module? And wonder if there was a recall of some sort for this item. Seems like everywhere I look, someone has one that's burnt. I even went to the junk yard trying to find the connectors, and the one in the 2001 Buick Park Ave. was starting to melt, and the connectors would not come out because it was burnt so bad. Ought to be some compensation from GM looks like to me