rear defroster very weak

[duboy]

I've noticed over the last 2 years (since we've owned her) that the rear defroster on our 03 4.6is has become very weak, to the point now where, during the time it is on, it will only defrost the upper drivers side quadrant about halfway. I tried to search but nothing was really applicable. Everything inside is otherwise functional, radio reception is fine, the defrost indicator light works and it shuts off after maybe 10 minutes? As far as the glass goes, nothing has been changed in the last 2 years, no work done on the hatch either. I inspected the lines and they look ok. Anyone have this issue with their rear defrost?

the only other thing i can think of is...same timeframe, our keyless entry reception range has been pretty terrible, sometimes standing right next to the X5 doesn't unlock until a few presses. Yes, a new key was purchased and programmed, same results. Don't know if it's related at all...thoughts?

[Qsilver7]

It could be related in that the aerial for the FZV key is incorporated into the lower section of the wires running through the rear window along with the defrost wires.

Again, I'm only saying that it "could" be related...further investigation would be required to determine if they actually are related.

Note in the diagram below that the E53's FZV/FM2 antenna amp is located/centered above the headliner at the rear of the roof...just before the upper lift gate. On its generational siblings (the e38/e39)...this amp is located in the C pillar:

[SlickGT1]

Check wires going through body into the lift gate. Chances are you got some chafing going on.

[X5SND]

Originally Posted by SlickGT1

Check wires going through body into the lift gate. Chances are you got some chafing going on.

Couldn't resist.

[SlickGT1]

Originally Posted by X5SND

Couldn't resist.

Lol. Some lube is all you need.

[TerminatorX5]

so, the symptoms are not of broken lines - it is just one side heats up more than the other side on the same wire run, right?

[SlickGT1]

I was actually thinking not getting full power to heat it up. He did say it was getting progressively worse.

[Gregory891]

Based on the symptoms, not broken grid wires - that's binary in function (YES or NO). This is either chafed / breaking-broken wires, but less likely. I'd more suspect a bad ground, likely in one or more of those that are attached with M6 bolts. Remove them all, clean with a wire brush and reinstall.

[duboy]

Thanks for the tips everyone. Just to verify, i cleaned the grounds on both sides of the hatch, which I believe are these two short cables. They were pretty dirty, but not too bad...After their cleaning, they keyless entry is now reliable as in, every time i push lock/unlock it does what it should do. However the range is not THAT much improved, it responds now from within 10ft of the X5. but the fact that when in range, it works reliably is a huge improvement. Before I could be standing next to the car and have to press 3 or 4 times before anything would happen.



I also checked on the FZV and I think i found the source of the rear defrost grid issue. I didn't notice this break because it was so close to the plastic trim. So i'm going to get a repair kit and fill this break. hopefully that will fix it.

[duboy]

Originally Posted by Qsilver7

It could be related in that the aerial for the FZV key is incorporated into the lower section of the wires running through the rear window along with the defrost wires.

Again, I'm only saying that it "could" be related...further investigation would be required to determine if they actually are related.

Note in the diagram below that the E53's FZV/FM2 antenna amp is located/centered above the headliner at the rear of the roof...just before the upper lift gate. On its generational siblings (the e38/e39)...this amp is located in the C pillar:

Just to clarify, the FZV is actually ON the rear hatch itself, top part right under the center plastic trim panel, the panel is held on with i think 6 or 7 metal clips, just pull with authority on each one and it'll pull off.