heated seat relay

Post by **Clemens** » 13 Jan 2022, 02:18

The other day when fixing the heated seat in my 94 I noticed it doesn't have a relay, as opposed to the 96 onward p80s having a relay. The parts number on the relay is listed as a 96 up p80 and 960 part.

What is the benefit of the relay? Does ist cycle the heater on and off (triggered by the thermostat)? Because my butt-o-meter tells me the 94 seats get alot warmer (which is nice, because it is my winter DD) than the ones in my 96.

Post by **Clemens** » 16 Jan 2022, 12:27

Noone?

454cid · Post by **454cid** » 16 Jan 2022, 12:43

Clemens wrote: ↑16 Jan 2022, 12:27Noone?

I'll try.... I've only had my 96 for about a week. I've noticed the seats don't seem to get very warm. Much more subtle warmth than I expected, but I've got about this much >< experience with heated seats except the hot seats I got from my dad when I was a naughty kid.

In general a relay would remove the high power demand from the switch and associated wiring, and possibly allow for a shorter power wire run. On my Chevy truck, I'm told the power for the headlights runs through the interior switch, making for a long run of wire carrying full power. One of the "mods" is using the OEM harness to trigger a relay, and power the headlights with a heavier dedicated power wire. This is done to improve headlight function, and relieve stress on the switch.

Post by **BEJinFbk** » 16 Jan 2022, 14:12

I finally found some time to check this out
and I don't see any relays downstream of the
front seat heater switches in any of the 850's.
It looks like they were added when the 850s
received their major facelift into the 70 series.
.

94 850 Heated Seats - TP3903202.pdf: (401.47 KiB) Downloaded 102 times

96 850 Heated Seats - TP3911202.pdf: (661.28 KiB) Downloaded 137 times

98 S-V70 Heated Seats.pdf: (369.91 KiB) Downloaded 105 times

.
Please bear in mind that these are all US spec
diagrams and may be a year behind models
built for other world markets.

Also, the US TP3917201 books for MY '97 only
seem to be updates for changes to the MY '96
TP3911202 diagrams and they don't include the
heated seats, so that's why there are no '97
PDFs included in this post.

As far as the t-stats in the lower cushion,
they only serve as high limit thermostats
that open the circuit at a given temperature.
These seat heaters have no timer functions.

At least up front. Although the rear seat
heaters appear to have a specialized
relay that may serve that function.
The diagram indicates an electronically
controlled relay, but doesn't call out it's function.
Any rear heated seat users have an answer?

I suspect that this electronic relay would
also be used with third row heated seats,
so any owners with that coveted option, sing out!

Post by **Clemens** » 17 Jan 2022, 05:53

Thanks for looking. Maybe the US market was behind, bacause my 96 R definitely has a relay dor the heated seats, but it is also a power seat, so maybe that's why.

Post by **abscate** » 17 Jan 2022, 05:58

We usually lag 1-2 years on auto upgrades, 50 years on health care and social justice

Post by **BEJinFbk** » 17 Jan 2022, 08:05

Clemens wrote: ↑17 Jan 2022, 05:53 Thanks for looking. Maybe the US market was behind, bacause my 96 R definitely has a relay dor the heated seats, but it is also a power seat, so maybe that's why.

Those are different and independent systems.
The only components in the heated front seats
are the ignition switch, the fuse, switches,
thermostats and heating elements.
It’s a pretty basic system.

Post by **Clemens** » 17 Jan 2022, 14:53

abscate wrote: ↑17 Jan 2022, 05:58 We usually lag 1-2 years on auto upgrades, 50 years on health care and social justice

Don't let the commies get you confused. Public healthcare is as evil as they say ...