Page 1 of 1

external ambient temperature sensor

Posted: Wed May 22, 2019 1:35 pm
by annieosc
Hi......I have an Volvo 480 celebration and the external temperature on my information centre showed -40C.Reading the forums it might be an open circuit.I replaced the sensor with one that is supposed to be for the car although it looks different.With this fitted the reading is -17C.The two wires feeding the sensor go into the main wiring harness and on I think into the cabin of the car.Any ideas where?Nothing in Haynes and no fuse details I can find.............Thanks John

Re: external ambient temperature sensor

Posted: Wed May 22, 2019 7:01 pm
by dcwalker
If the sensor you have looks different then it isn't the one for the 480. It might make no difference but first off I'd make sure you have the right one!

Is your info centre reliable? As in, does it work consistently and properly all the time? I only ask as these are notorious for all sorts of PCB solder problems, and that might be the issue rather than the actual sensor.

It is possible to check the various signal readings to the Info Centre - with car off, press and hold the reset button and turn key to position 2. Turning the selector switch now gives various readings in each position: at the external temperature position it should show a reference value indicating the resistance of the sensor. I'd need to check up exactly what it should be, but the point is that this should show you an open circuit in any event...

David

Re: external ambient temperature sensor

Posted: Thu May 23, 2019 9:13 am
by annieosc
Thanks for the information.I will try this today.I have another instrument panel with a speedo problem but I can possibly use it to prove if the fault stays the same.I bought the sensor from EBay and was assured it was for my car registration.It was a different shape to the original and I had to enlarge the hole a little for it to fit.The two wires feeding the sensor go into the loom which enters the cabin of the car.I just wondered where it goes from there before it reaches the information centre.
Thanks again..........John (celebration no 40/480)

Re: external ambient temperature sensor

Posted: Thu May 23, 2019 9:34 am
by jamescarruthers
I think DCWalker is right and you probably have the wrong sensor. The guys on eBay have probably told you in good faith that it will fit, but are likely wrong. 

It sounds like your original was open circuit (hence the very low temperature displayed-- the maximum the Info Centre can read) and the replacement is the wrong spec. so gives the wrong resistance for the temperature the Info Centre expects. 

Can you post a link to the eBay listing?‎

The sensors are normally pretty reliable so you should be able to get a second hand one pretty easily from someone on here and then plug and play!

Re: external ambient temperature sensor

Posted: Thu May 23, 2019 9:57 am
by annieosc
Thanks for the information.I am not sure how to post a link,but the Ebay item no is 382794330510 sold by LSM ltd and the 480 is listed on page 13.I will try to obtain an original if I can............John

Re: external ambient temperature sensor

Posted: Thu May 23, 2019 10:08 am
by jamescarruthers
I would say that that looks like an intake air temperature sensor (for the engine fuelling computer), not an ambient air temperature sensor! Keep it as a spare for your car.

Image

Where are you in the country? I have a friend on the south coast who can probably send you one in the post. ‎

Re: external ambient temperature sensor

Posted: Thu May 23, 2019 10:40 am
by dcwalker
If what you bought looks like what is in James' picture, then it is definitely the air intake temperature sensor - it is the one that sits in the front of the corrugated pipe between air filter and throttle valve.

So I suspect you have been sold the correct part for the 480, it is simply that it is the wrong kind of sensor entirely.

The fact it gave a reading though whereas the original you had effectively showed open circuit does at least suggest that the rest of the wiring is OK and it is the sensor in the grille itself that is at fault. If you cannot locate one I might have a spare kicking about - let me know if you'd like me to look.

Good luck!

David

Re: external ambient temperature sensor

Posted: Thu May 23, 2019 11:45 am
by annieosc
David and James......Well that solves the problem,I bought the wrong one!
I feel a bit daft but thanks to you two I have learnt a lot and thanks again.
If either of you could find me one that would be great.
I live in Liverpool and if you can tell me what I have to do re payment/postage.
Cheers..........John

Re: external ambient temperature sensor

Posted: Fri May 31, 2019 6:40 am
by annieosc
Replacement sensor sent from Keith Cooper in Bournmouth.Now fitted and Temperature reading now OK.

Thanks for the advice and information.......John

Re: external ambient temperature sensor

Posted: Sat Jun 01, 2019 5:07 pm
by dcwalker
annieosc wrote:
Fri May 31, 2019 6:40 am
Replacement sensor sent from Keith Cooper in Bournmouth.Now fitted and Temperature reading now OK.

Thanks for the advice and information.......John
Glad you got it sorted out! :D

David