P38A External Temp at - 40c

Andy Burrell · Mar 30, 2023

I had to disconnect the battery today so I could check all the connectors on the Becm were properly connected as the dashboard went blank again today. I unplugged and reseated all the connectors and the dash seems to be OK. However the external Temp on the HVAC is showing - 40c everything else is fine. Looking at the workshop manual I can't see if the external sensor goes via the Becm or direct to the HVAC. Any pointers would be great.
On the plus side I found 2p wedged under the drivers seat trim.

kermit_rr · Mar 30, 2023

If the hvac had power while the sensor was unplugged then it will go to -40. It won't change until the engine is running and even then it takes ages to get back to the correct value

Rubberknees · Mar 30, 2023

kermit_rr said:
If the hvac had power while the sensor was unplugged then it will go to -40. It won't change until the engine is running and even then it takes ages to get back to the correct value

Had that on mine a few years back. As Kermit says ran for 30 mins and all was fine

Datatek · Mar 31, 2023

kermit_rr said:
If the hvac had power while the sensor was unplugged then it will go to -40. It won't change until the engine is running and even then it takes ages to get back to the correct value

+1 ^^^^^^^. The sensor goes direct to the HEVAC

Andy Burrell · Mar 31, 2023

Datatek said:
+1 ^^^^^^^. The sensor goes direct to the HEVAC

That's what I thought looking at all the wiring diagrams, started to doubt myself though but a pure coincidence it happened after I had been fiddling elsewhere.

Andy Burrell · Apr 6, 2023

So today finally managed to get time to look at the issue. Ran up EAS Suite4 and interrogated the HEVAC it showed a sensor short error, probably where I had been unplugging things trying to sort out another issue, anyway cleared the error and it now shows the correct outside temp.

P38A External Temp at - 40c

Andy Burrell

Retired to the country

kermit_rr

Very

Rubberknees

Well-Known Member

Datatek

Well-Known Member

Andy Burrell

Retired to the country

Andy Burrell

Retired to the country

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