158 degree!!! "Fensterheber" window courtesy relay

[famoroso]

Greetings all,

I was doing some work today pulling an ancient (circa 1989) K40 radar detector install from behind the tank / oil and temp / press combo gauges and my hand brushed against the Fensterheber window courtesy relay (that's located behind the tank / oil combo gauge) and... OUCH! The relay was hot. Really, really HOT!!!

I grabbed my IR thermometer and verified that the relay was 158 degrees. Aye carumba!

I immediately unplugged my Porsche Charge-0-mat battery maintainer that had been plugged in for six days. I leave it plugged in when the car is parked in my garage. Sometimes, for weeks at a time. The Fensterheber relay is always energized (i.e. the power windows work, key-out, doors open or closed) when the Charge-o-mat is plugged into the cigarette lighter receptacle. I can hear the relay click on / off when I plug / unplug the Charge-o-mat from the cigarette lighter receptacle.

I'm surprised the Fensterhever relay hasn't died yet as a result. So, I guess I'll be adding a harness to the battery and connecting my Charge-o-mat directly to the battery from now on.

Couple of pics borrowed from fellow Pelicans...

[DRACO A5OG]

Hmm, it appears your door light switches are working to disable that relay. Does your dome lights work?

[famoroso]

Originally Posted by DRACO A5OG

Hmm, it appears your door light switches are working to disable that relay. Does your dome lights work?

You mean "not" working?

The dome lights work properly. As do the door switches. When the Charge-o-mat is not plugged into the cigarette lighter receptacle, with ignition key out, the power window circuit de-energizes upon opening the door(s) and the power windows no longer operate.

[timmy2]

Or, run a fused wire directly to the lighter from the battery like I did a few years ago. I like the convenience of constant power to the lighter socket and getting it off of the infamous interior lighting main dash harness melt down circuit...
I ran a #12 awg wire from a spare fuse terminal (1) on the bottom to the lighter, and the same from the top of the fuse to the batter positive. PITA to access the back of the lighter socket from the frunk, but worthwhile I'm my opinion.
I plug my charger in with no worries about energizing any other circuits. Also ignition doesn't need to be on to charge a phone...

[DRACO A5OG]

Hmmm? so a cigarette lighter charger affects the relay, good to know.

[famoroso]

Originally Posted by DRACO A5OG

Hmmm? so a cigarette lighter charger affects the relay, good to know.

Yes, the plot thickens even.

When you run Philips LED brake lamp bulbs on a Cruise Control equipped car (mine is an '88) the bulbs may light dimly when the ignition is switched on (with the brake pedal unapplied). The CC dumps a small amount of current into the brake light circuit. Anyway, ignition off, brake pedal not applied and Charge-o-mat plugged into cigarette lighter receptacle and... The LED brake lamps similarly dimly light-up.

So, +12V to the cigarette lighter receptacle, ignition off, does at least a couple of things, including energizing the Fensterheber relay and doing something with the CC system. Who knows what else(?).

Anyway, I'll be going direct to battery for trickle / maintenance charging duties going forward.

[Joe Bob]

Time to get a Battery Tender by DelRay. I have leads permanently attached to the battery, the end has a cap. Two pronged plug.

Car can be locked and secure, leads out the closed trunk lid.