Contour Enthusiasts Group Archives Forums General Troubleshooting Darn Rear Defroster Grid

Hi...

The middle three wires of the rear defroster grid on my 99 Mystique LS don't seem to do anything. The rest of the wires clear off
the glass nicely.

I assume I have some tiny breaks in the bad wires somewhere, but CANNOT visually detect any.

1. I understand from searching the Forums that there's some kind of LocTite (?) stuff available to bridge breaks in these wires, but how to FIND the breaks to start with?

2. Has anyone had good or bad luck with the LocTite (or similar product) fix-it method?

3. If there are actually NO breaks in the wires, is there any other troubleshooting I can try to isolate/fix this problem?

4. If this is a manufacturing defect, did Ford ever issue a recall for the rear defroster?

Thanks!
Hal
(with semi-frosted rear window)

Had similar problem in my 99 SVT, dealer had to replace entire rear glass.

  There's a product available to make do-it-yourself repairs to damaged defogger traces.  I've used it myself with considerable success.  Under the Loctite brand, it's their product # 79340?15067, ?Quick Grid Rear Window Defogger Repair Kit?.  No need to even think of replacing the whole bloody window over a thing like this.

You could probably use an ohmmeter, slide one probe along the suspect wire while the other probe is on one side of the window. When the resistance goes up to infinity there's the break. (There may be more than one break in the wire, so fix it and test again).

I'm assuming the wire isn't coated with something non-conductive, otherwise this won't work.

Mike Patton Ford would LOVE to know this.

Has anyone tried measuring the defroster wires with an ohmeter?

That is, are the wires coated with some type of insulation layer that will get chewed up when I (carefully) jab them with test probes?

Thanks again,
Hal

Using an ohmmeter ANYWAY! You can find the terminal of one side at the corner somewhere and use a PIN ,or needle, on just the area not working to find just WHERE the break (no JUICE flowing on meter) is, then fix the spot invisible break or not, with the stuff.

an ohmmeter wouldn't work, since the wires are all commonly connected at either side, you would still read a 0 resistance.

Hal,
Since I have this problem, too, possibly the same 3 gridlines, I looked it up in the service manual. Surprisingly there is a detailed writeup. Here is the most important information from my (1995) manual, good luck!

Information from the factory service manual:

The grid lines consist of two layers. The outer layer is brown, the inner layer silver.
TESTING:
- Using a bright lamp inside the vehicle, visually inspect the wire grid from the outside. A broken grid wire will appear as a brown spot.
- Run engine at idle, turn on rear defroster.
- Working inside the vehicle with a voltmeter, contact the broad red-brown strips on the rear window, positive lead to battery side and
negative lead to ground side. The meter should read 10-13 volts. A lower reading indicates a loose defroster ground wire - check the
defroster ground wire attaching screw.
- Contact a known ground point with the negative lead, the voltage reading should not change.
- With the negative lead of the meter grounded, touch each grid line at its midpoint with the positive lead. A reading of ~6V indicates the line is good. A reading of zero V indicates that the line is broken between the midpoint and the B+ side of the grid line. A reading
of 12 V indicates that the circuit is broken between the midpoint of the grid line and ground.

REPAIR:
Any break in the grid longer than 25m / 1 in. cannot be repaired.
If the brown layer is damaged or missing, apply brown lacquer touch-up paint on the window glass prior to applying the Rear Window Defroster Repair (D8AZ-19562-AA).

-The vehicle should be warmed to 60 deg F or above.
- Clean the repair area with window cleaner.
- Mask off the area above and below the grid line.
- If brown layer is broken/missing, apply 2 coats touch-up paint. Extend 1/4" past both ends of the break.
- Apply 3 coats of grid repair, Extend 1/4" past both ends of the break.
- Allow 5 minutes to dry before removing mask.
- Defroster can be energized after 3 to 5 minutes.

Many thanks for the info, Pangloss. I will try this ASAP.

Sounds like another Ford quality control problem. The brown outer layer can be visibly intact everywhere, but apparently there are some breaks in the underlying conductive silver layer.

They must have had a bad day in the defroster grid department when they made my rear window.

Does anyone know if there was a recall or owner notification issued for this?

Hal