Retrofit rear seat heating: Were do I find the best power supply?

[brynar]

I have just ended my installation of a pair of seat heatings to the rear back rest. Everything works perfect until I found a flaw: I wired the heating to the rear fuse box as I was pretty sure to find switched fuses (Power supply when ignition is on) but when installing the wirings I discovered it seems all the fuses (power supplies) get power from the battery even if I turn off the ignition.

As I understand the car has a "Sleep mode" - It turns off the power supply after 20 min. (or is it 60min?) If so I don't know how to control it. Furthermore its obviously not the best solution ( I want the power supply to shut off with the ignition)

Has someone a good solution? I already put allt the interior stuff back, so I prefer to find a better supply from the rear (right) of the car.

Best Wishes
André
Sweden

[edjack]

The sleep mode is entered after 16 min.

Might be simple to use a relay to switch power from a fused source at the boot, and operate the relay from switched power; e.g., from the amp.

[brynar]

Hm, im not sure I got it.
As for now I have two relays operating the two switches for the heater (left and right back seat High-off-Low) From these two relays I wired them to the fuse box to a Non-switched fuse.
If someone forgets to turn the seat heating off I'm not sure if the heater will turn off after 16 min. (Have to check this) If so its ok but not as good as if using a switched power source. If I understand you correct you mean I could take it from the Amplifier in the boot? ( I don't have it) I was thinking of using some wiring to the back lights but it seems odd not to find a power supply at the fuse box. (Sorry for my English - im more into Swedish)

[Mike WW]

These cars can be tricky to add things to. On my 02 525it all the fuses in the trunk are unswitched. Even the radio, everything uses the Buss to control things and tells things to shut off, rather than removing power. So you would have to rely on a timer or a relay switched by the ignition, including running a wire from the front. All doable, but a bit more complicated.

And no worries about your English, there's plenty of people born here who don't write as well, you do just fine.

[JimLev]

None of the fuses you mentioned will shut power off after 16 min.
Show us a pic of the relays you have in the boot above the battery. At least one of them must be controlled by the ignition.
I've done a lot of rewiring on my car, it's not hard. You just need to know what relays and wires do what.
As Mike said your English is just fine.

[brynar]

Thanks for your answer. Here a pic of the three relays above the battery/fusebox662292

[JimLev]

There are some differences between a Euro and US E39's...so...
Do you have fuse 19 in the trunk? If so, the power to that fuse is controlled by the ignition switch.
F19 is a 5 amp fuse, you would need to add a relay with the relay coil controlled by F19. The relay contacts would switch power to your seat heater switches.

If you don't have F19 installed are there wires to that fuse location?
Do you know the K numbers for the relays in your pic?

[brynar]

662303
Hmm, im not sure I follow you here. The fuses in the trunk starts with F49?

[brynar]

Here is the spare part number and link for the left and the right relay:
https://www.schmiedmann.com/displayproductdetails.aspx?id=1956998&produkt=61-36-8-373-700

[brynar]

I think I have a solution here - Or I understand your solution better, Jim - Look att the picture. I hope I got it right
662316

[JimLev]

662303
Hmm, im not sure I follow you here. The fuses in the trunk starts with F49?

I looked at a schematic that showed F19, however your pic above shows F60 (and F19) in the same circuit. F60 should be switched by the ignition.

- - - Updated - - -


I think I have a solution here - Or I understand your solution better, Jim - Look att the picture. I hope I got it right
662316

Yes, that looks correct.

[brynar]

Great Jim!
I will look in to it first thing in the morning (its pretty dark and cold in Sweden now - that's why I installed the heaters). I hope the F60 fuse will work as you said. If not - I go for the relay solution.
I give you a status update.

[JimLev]

Check this out.

https://www.newtis.info/tisv2/a/en/e39-530i-lim/components-connectors/components/k-relays/relays/k93-load-shedding-relay-terminal-15/hfyGpwa

https://www.newtis.info/tisv2/a/en/e39-530i-lim/components-connectors/components/k-relays/relays/k93-load-shedding-relay-terminal-15/vI9ITzs

[brynar]

I was looking at F60 but unfortunately it wasn't any wiring connected - thus I don't have no EDC (BMW 530 touring 2001) Jim - sorry but don't understand the links. I guess you mean the already mounted relays above the fuse box?

[JimLev]

According to the pic in this link below the first relay in your pic (post 6) is the unloader relay.
https://www.newtis.info/tisv2/a/en/e39-530i-lim/components-connectors/components/k-relays/relays/k93-load-shedding-relay-terminal-15/Ue7umxr


Put your meter on pins 85 and 86 to see if power is switched on/off with the ignition.

https://www.newtis.info/tisv2/a/en/e39-530i-lim/components-connectors/components/k-relays/relays/k93-load-shedding-relay-terminal-15/vI9ITzs (https://www.newtis.info/tisv2/a/en/e39-530i-lim/components-connectors/components/k-relays/relays/k93-load-shedding-relay-terminal-15/vI9ITzs)

[brynar]

I bought a new relay for $3 and put the fused power cable from the heaters to the radio fuse (F56) and used the right tail light cable as switch (In Sweden the lights goes on when you turn the ignition on) I have tested the configuration - it works great. No more worries leaving the seat heater on after turning off the ignition. Thanks all of you for great support..