No heat seat

mrhook · Oct 3rd, 2016, 18:42

Volvo V70 my06 2.4l 170hp. Nothin fancy pancy. Just bought the car and the dealer and he refuses to sort it out, which leaves me in dispair of trying to fix it myself.

So I have no heat seat i either seats, drivers nor passenger side. I have voltage 15 volt to the thingy under the seats and meassured the seat elements to about 1 ohm in resistance.

What could possibly be the fault since the elements and the voltage is there and correct. Could it be the CCM or some relay spooking arround?

Would be so happy to get them working to the winter.

(excuse my poor eng writing, not native)

cheshired5 · Oct 3rd, 2016, 19:21

You should be getting battery voltage going into the heater module and much less voltage coming out to the pad plugs...... around 5v delivered in pulses/waves so check the module out voltage.

Pad resistance needs to be less than 1ohm.

Simon Jones · Oct 3rd, 2016, 19:29

I believe it uses what is known as pulse width modulation (PWM) whereby the voltage is switched on and off rapidly to control the temperature. That means you can't just connect up a 12v to the element and expect it to work. Likewise, you may not be able to get an accurate reading with a digital multimeter as demonstrated by the 15v you are seeing.

Can't offer much assistance with regard to resolving the problem with the dealer other than it's a 10+ year old used car and it's not they type of mechanical fault that a dealer warranty would normally cover.

mrhook · Oct 3rd, 2016, 19:30

Quote:

Originally Posted by cheshired5

You should be getting battery voltage going into the heater module and much less voltage coming out to the pad plugs...... around 5v delivered in pulses/waves so check the module out voltage.

Pad resistance needs to be less than 1ohm.

On one of the circuits I had 0.4 ohms and the other about 1.3 ohms and we gotta take off about 0.3-4 ohms for the multimeter cables. So the OHM should be fine I supose. Check the connectors that nothin seemed burnt there.

I have 15 volts in and should have about 5 volts out, ok... will check that and see if that is the case.

Lets say that I ahve everything on the right side in that perspective that the seat is all fine. What could be wrong apart from that?

mrhook · Oct 3rd, 2016, 19:32

Quote:

Originally Posted by Simon Jones

I believe it uses what is known as pulse width modulation (PWM) whereby the voltage is switched on and off rapidly to control the temperature. That means you can't just connect up a 12v to the element and expect it to work. Likewise, you may not be able to get an accurate reading with a digital multimeter as demonstrated by the 15v you are seeing.

Can't offer much assistance with regard to resolving the problem with the dealer other than it's a 10+ year old used car and it's not they type of mechanical fault that a dealer warranty would normally cover.

I know that but in the car declaration it is stated that they are under normal funtion and not that they are faulty. But we'll see in the future what is resolved and not in that matter. WOuld be nice though if I got some heat

So PWM that aint easy to test I guess, but could it be a faulty CCM since the signal is sent from there?

mrhook · Oct 3rd, 2016, 19:57

The fault codes I have for this issue are: CCM-DD12 and CCM-DD30, no signal to either seat.

Could it be the relay-box under the seat that have broken on both sides.

cheshired5 · Oct 3rd, 2016, 21:15

Quote:

Originally Posted by mrhook

On one of the circuits I had 0.4 ohms and the other about 1.3 ohms and we gotta take off about 0.3-4 ohms for the multimeter cables. So the OHM should be fine I supose.

Check your leads resistance again. I would expect 0.1 to a maximum of 0.2 even on cheap leads which would give a net reading over 1.0 ohm which may be too high.

Let us know when you get a module out voltage at the plugs.

mrhook · Oct 4th, 2016, 08:32

Quote:

Originally Posted by cheshired5

Check your leads resistance again. I would expect 0.1 to a maximum of 0.2 even on cheap leads which would give a net reading over 1.0 ohm which may be too high.

Let us know when you get a module out voltage at the plugs.

I have now tried to meassure the cables and this is what I have found if you have a look att the picture.

The thermostat or thirmister i did not manage to get a reading of in either voltage nor ohm's.

I have checked the fuses on the dashboard side and they are fine. But I have no clue to if there are any fuses in the CEM that could be faulty if someone is pointing to towards the fuses.

cheshired5 · Oct 4th, 2016, 08:55

So you have volts into the module but not out which could point towards a faulty module but on the thermostat pins, you should be getting a few thousand ohms at least so if that is open circuit, I would say that your problem lies there.
To be certain, unplug the seat base and resistance test the thermostat pins again.

mrhook · Oct 4th, 2016, 09:22

For some more information I alsao tested the input side to the seat which can be viewed in the picture below.

Oct 3rd, 2016, 18:42	#1
mrhook New Member Last Online: Oct 7th, 2016 08:50 Join Date: Apr 2014 Location: Orebro	No heat seat Volvo V70 my06 2.4l 170hp. Nothin fancy pancy. Just bought the car and the dealer and he refuses to sort it out, which leaves me in dispair of trying to fix it myself. So I have no heat seat i either seats, drivers nor passenger side. I have voltage 15 volt to the thingy under the seats and meassured the seat elements to about 1 ohm in resistance. What could possibly be the fault since the elements and the voltage is there and correct. Could it be the CCM or some relay spooking arround? Would be so happy to get them working to the winter. (excuse my poor eng writing, not native)

Oct 3rd, 2016, 19:21	#2
cheshired5 Premier Member Last Online: Dec 26th, 2021 13:42 Join Date: Dec 2013 Location: Crewe	You should be getting battery voltage going into the heater module and much less voltage coming out to the pad plugs...... around 5v delivered in pulses/waves so check the module out voltage. Pad resistance needs to be less than 1ohm. __________________ 2002 S60 SE D5 Manual 209000 miles

Oct 4th, 2016, 08:55	#9
cheshired5 Premier Member Last Online: Dec 26th, 2021 13:42 Join Date: Dec 2013 Location: Crewe	So you have volts into the module but not out which could point towards a faulty module but on the thermostat pins, you should be getting a few thousand ohms at least so if that is open circuit, I would say that your problem lies there. To be certain, unplug the seat base and resistance test the thermostat pins again. __________________ 2002 S60 SE D5 Manual 209000 miles

Oct 3rd, 2016, 19:29	#3
Simon Jones Premier Member Last Online: Jan 15th, 2022 11:23 Join Date: Feb 2009 Location: Salisbury (ish)	I believe it uses what is known as pulse width modulation (PWM) whereby the voltage is switched on and off rapidly to control the temperature. That means you can't just connect up a 12v to the element and expect it to work. Likewise, you may not be able to get an accurate reading with a digital multimeter as demonstrated by the 15v you are seeing. Can't offer much assistance with regard to resolving the problem with the dealer other than it's a 10+ year old used car and it's not they type of mechanical fault that a dealer warranty would normally cover.

Oct 3rd, 2016, 19:57	#6
mrhook New Member Last Online: Oct 7th, 2016 08:50 Join Date: Apr 2014 Location: Orebro	The fault codes I have for this issue are: CCM-DD12 and CCM-DD30, no signal to either seat. Could it be the relay-box under the seat that have broken on both sides.

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