ECU engine temp input

[Blackdog]

Hi,

Can anyone advise where the ME7 ECU gets its engine temperature reading from.

The temperature gauge is coming up as normal but the ECU is only reading at a constant 27 Deg C?

Is it an oil temp that it picks up?

The Car is a '99 V70R Phase 2.

Ref "Seriously tempted by this" thread - Yes it is a phase 2 - Blue engine cover, four speed auto, AWD and 2319 cc on the log book.......LOL

[burnout8488]

There is a coolant temperature sensor on the bottom of the thermostat housing. No other temp sensors that I know of.

[deathrider311271]

As above spot on mate

[960kg]

There is a coolant temperature sensor on the bottom of the thermostat housing. No other temp sensors that I know of.

Although not an engine temp sensor there is also the Ambient Temp. Sensor just behind the front bumper which does the digital temp on the dash but the ECU also takes readings from this to adjust finer fuel mixes.

[LeeT5]

Although not an engine temp sensor there is also the Ambient Temp. Sensor just behind the front bumper which does the digital temp on the dash but the ECU also takes readings from this to adjust finer fuel mixes.

Your sort of correct. The ambient air temp sensor in the bumper is for the digital dash display and for the CCM (Climate Control Module). Using this sensor it can adjust the climate control accordingly dependant on what the other sensors are reading....ie Dashboard light sensor, cabin temperature sensor (in the lower dash) etc.

The ambient temp' sensor is not used as part of the cooling system and therefore, plays no part in what the coolant temp guage reads. Your problem lies solely with the CTS (Coolant Temp' sensor). Replace it and your ECU will read the correct temps again.

[Wobbly Dave]

The ME7 version 1 that I have in my C70 gets the IAT from a sensor on the plastic inlet pipe just prior to the ETM.

Is that what you mean?

[Blackdog]

It was the coolant temp sensor.

Changed and all sorted....

In that department anyway.

[LeeT5]

Your problem lies solely with the CTS (Coolant Temp' sensor). Replace it and your ECU will read the correct temps again.


It was the coolant temp sensor.

Changed and all sorted....

In that department anyway.

God i'm good! :saythat:

[960kg]

Your sort of correct. The ambient air temp sensor in the bumper is for the digital dash display and for the CCM (Climate Control Module). Using this sensor it can adjust the climate control accordingly dependant on what the other sensors are reading....ie Dashboard light sensor, cabin temperature sensor (in the lower dash) etc.

The ambient temp' sensor is not used as part of the cooling system and therefore, plays no part in what the coolant temp guage reads. Your problem lies solely with the CTS (Coolant Temp' sensor). Replace it and your ECU will read the correct temps again.


God i'm good! :saythat:


Mmmmmmmm.......i wouldn`t put it quite that way!

The OP did not really say he had a problem just wanted to know which sensors did what and of course it is obvious that replacing the Engine Temp. Sensor would put the reading correct.

The thing is i do hate those type of people that will knock others intelligence because they do think they know it all and also are prepared to air or advertise it publicly.

The Ambient Air Temp. Sensor has nothing at all to do with the Electronic Climate Control. The ECC maintains the desired temperature in the car irrespective of the temperature outside. The actual physical temperature takes into account factors such as air speed and humidity and intensivity of sunlight on the driver`s and passenger side inside the car via the small vent on the dash and also the solar sensor on top of the dash.

What the Ambient Temp. Sensor deals with is in the pictures.......But i won`t say i told you so already!

You must think before you press that submit button :kiss:

[LeeT5]

The OP did not really say he had a problem just wanted to know which sensors did what and of course it is obvious that replacing the Engine Temp. Sensor would put the reading correct.



BD did infact have a problem whether he was asking about it or not. He said his OBD ecu readings were 27*C and that his guage was reading normal ie 90*C, that in itself is a fault!

I have seen this type of fault hundreds of times and thus correctly diagnosed the fault as CTS. My comments i made after were not serious and i was merely taking the p*** in my reply in a friendly manner. If it was so bloody obvious then he wouldn't be asking in the first place, would he!? There is absolutely no need for you to be cocky in your reply, like your trying to prove something??

Anyway,I thankyou for your diagrams on what infact the bumper sensor actually does (and putting me straight) i was of the understanding that this sensor was merely an outside sensor for the CCM, clearly not on the Volvo P2 then?
Obviously there must be another temp. sensor that informs the CCM otherwise the CCM has no means of comparing the cabin temp. to the outside temp. for comfort settings?
Your diagram of the outside temp.sensor does explain why it's difficult to diagnose a faulty MAF in cold whether because that part of the ECU's sensor is disabled, meaning the ECU no longer recieves a faulty signal from the MAF when temperature is below 7*C.

As for sensors in the vents? The cabin temp. is measured from the sensor in the upper part of the CCM and like you said, sunlight is measured from the SIngle solar sensor on the middle of the dash. AFAIK there are no temp. sensors in the vents.
I did hear once that someone said there were two additional temp. sensors fitted into the B pillar on either side of the car. These are to check for hot spots in the cabin and ensure cabin temps are the equal esppecially when CCM settings are set to 'Auto'. I may be wrong on that, but like i said (before you jump down my throat) it was from hearsay, possibly a main dealer tech a few years aga now.

[960kg]

I am sorry and do apologise how i answered!....i did not mean any harm.

The sensors at the top of the B pillars either side are for the ultra sound alarm.

There is a Passenger Compartment Temperature Sensor which is to the right of the ECC unit in the dash and is incorporated in something of the shape of a blank switch like they use for accessories, yours may be different being phase 2, but it is behind a same coloured mesh as the dash.

There is another sensor called an Outside Temperature Sensor but it is not outside the car but outside the ECC contained unit inside the car. This sensor is behind and should be level with bottom of the glove compartment door, it is behind all the panels etc.
I hope this helps?