Rear defrost weak

98, Lmtd, 160K...

Title says it all...rear window defrost is very weak. I'm getting voltage on the left (driver's) side only of the grid. Each line will illuminate the test light (weakly) but by halfway across (towards pass), there is nothing.

It doesn't seem like there is a break in the grid...just very weak. Any ideas where to start? Should this be supplied with 12v?

Thanks!

hh65flyer said:

I'm getting voltage on the left (driver's) side only of the grid. Each line will illuminate the test light (weakly) but by halfway across (towards pass), there is nothing.
Thanks!

Click to expand...

That result is normal.
yes, fed with 12v.

make sure that the wires are not breaking apart in the accordion tubing in the hinge.

Which part is normal? Even with a full 12v only the driver's side will show voltage? I haven't measured yet but it seems low just because the test light is very dim.

I had the wiring apart there once before and there were five broken wires causing all sorts of issues. I repaired them with solder, etc and put it back together. Could still be the issue though. I would like to get a good harness but proving difficult to find...

the result you got is normal.

full 12v at drivers side, and because the ground is passenger side, and the grid is technically a resistor, the voltage drops as you move to the right, causing the test light to get dimmer.

Great...thanks Digger. I just tested the voltage and it's only reading about 10.5. The voltage actually gets lower (to about 9.0) as I tested from the top of the glass to the bottom (driver's side). Again, prob normal.

Perhaps my 'repairs' weren't good enough and there's too much resistance through the wire or repaired area. IDK, but it would be good to see 12v there. Thanks again.

test it while engine is running.