G8 seat swap getting the heated seats to work?

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Groundczero
Posts: 93
Joined: Thu Sep 20, 2018 7:52 am

G8 seat swap getting the heated seats to work?

Post by Groundczero »

I have seen a couple people swap the seats, but I am wondering if anyone has done this and got the heated seats to work, did they use the buttons from the g8 in the center console?
gno
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Joined: Wed Mar 11, 2020 3:22 pm

Re: G8 seat swap getting the heated seats to work?

Post by gno »

if you don't mind going the aftermarket route you can buy heated seat panels for cheap and wire them in to any seat. i plan on doing it to my stock ppv seats when i have them recovered
Groundczero
Posts: 93
Joined: Thu Sep 20, 2018 7:52 am

Re: G8 seat swap getting the heated seats to work?

Post by Groundczero »

gno wrote: Tue Mar 17, 2020 1:26 pm if you don't mind going the aftermarket route you can buy heated seat panels for cheap and wire them in to any seat. i plan on doing it to my stock ppv seats when i have them recovered
I have seen that but was hoping to use the buttons from the g8 in the center console.
gno
Posts: 6
Joined: Wed Mar 11, 2020 3:22 pm

Re: G8 seat swap getting the heated seats to work?

Post by gno »

Groundczero wrote: Wed Mar 18, 2020 10:37 am
gno wrote: Tue Mar 17, 2020 1:26 pm if you don't mind going the aftermarket route you can buy heated seat panels for cheap and wire them in to any seat. i plan on doing it to my stock ppv seats when i have them recovered
I have seen that but was hoping to use the buttons from the g8 in the center console.
yeah that makes sense, I'm sure you could tap the wires of an aftermarket kit if nothing else
xcidmigs
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Location: SE PA

Re: G8 seat swap getting the heated seats to work?

Post by xcidmigs »

I suggested this years ago and even bought the switch, the short answer is it can't be done, the G8 stuff runs everything through the BCM, would require reprogramming this and tons of wiring I don't know where you would get at. The switches are not simply a on off switch its a negative ground trigger that GM loves and again has to run to seat heater modules which the G8 has mounted to each seat. If you have that stuff and the wiring harness maybe its possible but I gave up....
http://www.newcaprice.com/forum/viewtop ... =21&t=3241

Check the zero replies....
smwalker
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Re: G8 seat swap getting the heated seats to work?

Post by smwalker »

Here is the description of the heated seats operation. I think they only reason they interface with the BCM is so that the BCM can shut them off if detects a low voltage situation in the car. Think you could get by without that especially on a PPV with a higher amp alternator.

Description:
The heated seats consist of the following components:

Left heated seat control module

Left heated seat switch

Left seat cushion heating element

Left seat back heating element

Left seat cushion temperature sensor

Right heated seat control module

Right heated seat switch

Right seat cushion heating element

Right seat back heating element

Right seat cushion temperature sensor

Modes of Operation
Both front heated seats are controlled independently of one another and each heated seat has its own heated seat module (HSM). The heated seats have only one mode of operation. The heated seat cushion base and the heated seat back cannot operate independently of one another.

Heated Seat Switch/LED Indicators Operation
Ignition voltage is supplied to the heated seat switch fuse via fuse F38/10A located in the under-hood fuse block. The body control module (BCM) supplies voltage to the heated seat switch LEDs and the heated seat module (HSM) supplies a ground signal to the heated seat switch LEDs.

The heated seat switch indicates 3 heat level settings.

Low Temperature – When the heated seat switch is depressed once, ignition voltage is supplied via the heated seat switch contacts and the heated seat switch signal circuit to the HSM. The HSM then supplies a ground signal to one of the heated seat switch LEDs to indicate that the first heating level is active.

Medium Temperature – When the heated seat switch is depressed for the second time, ignition voltage is supplied via the heated seat switch contacts and the heated seat switch signal circuit to the HSM. The HSM then supplies a ground signal to the second LED of the heated seat switch. Two LEDs will be lit indicating that the second heating level is active.

High Temperature – When the heated seat switch is depressed for a third time, ignition voltage is supplied via the heated seat switch contacts and the heated seat switch signal circuit to the HSM. The HSM then supplies a ground signal to the third LED of the heated seat switch. Three LEDs will be lit indicating that the third heating level is active.

System OFF State – When the heated seat switch is depressed for a fourth time, ignition voltage is supplied via the heated seat switch contacts and the heated seat switch signal circuit to the HSM. The HSM then switches OFF the ground supply to the LEDs. No LEDs will be lit indicating that the heated seat system is in the OFF state.

Heated Seat module Operation
A continuous battery voltage is supplied to both heated seat modules via fuse F19/15A located in the instrument panel (I/P) fuse block. Ignition voltage is supplied to both heated seat modules via fuse F38/10A located in the under-hood fuse block. Ground for both heated seat modules are supplied via G305 and G304 respectively.

The three heat level settings of the heated seats are selected by depressing the heated seat switch consecutively. Upon depressing the heated seat switch for the fourth time, the heated seat will switch OFF.

Depending on the heat level selected, the HSM supplies voltage to the seat cushion base and the seat back elements. The different temperature levels of the seat cushion base and the seat back elements are monitored by the HSM via a temperature sensor. When the seat cushion base and seat back heating elements reach a predetermined value stored within the HSM, the voltage supply to the seat cushion base and seat back heating elements are switched OFF. When the temperature drops below a predetermined value stored within the HSM, the HSM switches the voltage to the seat cushion base and seat back heating elements ON, thereby regulating the temperature. The HSM supplies a ground signal to the first LED of the heated seat switch and level one setting is shown as active.

Temperature Regulation
The HSM regulates the heated seat temperature in accordance with the input values of the thermister which is situated in the seat cushion base close to the seat heating element.

Thermisters are variable resistors. Their resistance varies as temperature changes. When the thermister resistance reach a predetermined value stored within the HSM, the HSM switches the voltage to the seat cushion base and seat back heating elements OFF. When the temperature drops below a predetermined value stored within the HSM, the HSM switches the voltage to the seat heating elements ON, thereby regulating the seat cushion base and seat back heating element temperatures.

Load Management
The electrical power management function is designed to monitor the vehicle electrical load and determine when the battery is potentially in a high discharged condition. The heated seat system is one of the vehicle loads that is subject to being switched OFF during a battery discharged condition. For more information on load management refer to Electrical Power Management Description and Operation.
Steve Walker
Azusa, CA
'11 PPV 9C3 Huron White
Jay_Z
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Joined: Fri Apr 15, 2022 7:22 pm

Re: G8 seat swap getting the heated seats to work?

Post by Jay_Z »

smwalker wrote: Mon Mar 30, 2020 3:28 am Here is the description of the heated seats operation. I think they only reason they interface with the BCM is so that the BCM can shut them off if detects a low voltage situation in the car. Think you could get by without that especially on a PPV with a higher amp alternator.

Load Management
The electrical power management function is designed to monitor the vehicle electrical load and determine when the battery is potentially in a high discharged condition. The heated seat system is one of the vehicle loads that is subject to being switched OFF during a battery discharged condition. For more information on load management refer to Electrical Power Management Description and Operation.
@smwalker

The G8 BCM connection is at X3/25, which is an unoccupied position in the Caprice BCM. Do you know what the BCM provides from this position? I'm assuming the Caprice BCM would have to be programmed for this functionality to be added, but do you know if there is a constant signal on this wire that cuts out in low voltage conditions, or is it the opposite, where this channel is dead until the voltage is low, which sends a signal to cut the power? I have the G8 seats and console switch, I don't want to reprogram my BCM (again) so I'm just wondering if I would need to give that wire a constant voltage, or if just leaving that position empty on the switch would be enough.

The description on the pinout diagram for the switch describes that as "heated seat supply voltage" which makes me think it may need some power, possibly a 5v signal or something?

I know this is an old thread, but any help would be greatly appreciated!
smwalker
Administration Staff
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Location: Azusa,CA

Re: G8 seat swap getting the heated seats to work?

Post by smwalker »

Man all good questions.

Here is the diagram from the 08 G8:
https://appcontent.chiltonlibrary.com/c ... 075281.pdf

On that diagram it shows the connection at the BCM
BCM finction.png
BCM finction.png (15.92 KiB) Viewed 1368 times

That symbol is described as: I/O Pull-Up Resistors (+) The plus symbol there is key as there are negative or ground pull down resistors as well.
pulldown.png
pulldown.png (11.74 KiB) Viewed 1368 times
What does that mean? No idea!! Here is a description:
https://learn.sparkfun.com/tutorials/pu ... istors/all
Steve Walker
Azusa, CA
'11 PPV 9C3 Huron White
Jay_Z
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Joined: Fri Apr 15, 2022 7:22 pm

Re: G8 seat swap getting the heated seats to work?

Post by Jay_Z »

Checking the symbols in the box never occurred to me, that is very valuable insight. I did a little reading, and I came to the same conclusion that you did. No idea!

I think there are probably only 3 options for that wire: open, ground, or +5v. If anyone out there had a running G8 with heated seats, it would be very easy to find out, however I will probably proceed with a guess and check method. There is no interior in my car at the moment, I'm working on wiring and sound deadening. I'll have the seat connectors repinned in the next day or two, then I'll be able to do some testing. I'll be sure to update this thread with what I find out. With as many guys that have these G8 seats I'm really surprised that nobody has got this working yet, of course, it's always possible that I won't get it working either.
Jay_Z
Posts: 6
Joined: Fri Apr 15, 2022 7:22 pm

Re: G8 seat swap getting the heated seats to work?

Post by Jay_Z »

After much delay due to life and lack of time to work on the car I'm very happy to announce that the G8 heated seats are working normally. To answer the previous question, the PU/WH wire needs to see voltage for the seats to function, or at least for the indicator lights to light. I just connected it to the Pink/Dark Blue ignition wire on the passenger side switch connector. Otherwise, the wiring is pretty straight forward, just match the high/low, temperature indicator, intermediate signal, and low temperature indicator wires for both passenger and driver to the respective wires under the seats, these pins will need to be added to the caprice seat connectors if you do it the way I did, or you would need to replace the caprice seat connectors with the G8 seat connectors. Aside from that, I used the spotlight 12v supply wires from the caprice harness to add the secondary 12v+ for the heated seats, and added a second ground wire as well. Interestingly enough, the fuse locations that feed the spotlights are the exact same fuse locations that feed the heated seats in the G8. Now, since the signal from the bcm is spoofed as ignition voltage, the BMS will not protect your battery from the amp draw of the heated seats if your battery gets low. This was the main feature that I wanted to retain from the G8 seat swap, now I just have to put all of the interior back in my car so that I can drive it before the end of this winter!
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