Does anyone know where the ambient temp sensor sends its info to? 2012 mercedes in freightliner. Dash reads 80 degrees when below zero outside. put in a new one and now it reads 40 below zero when above freezing. truck in derate to only 700 mrpm and red and yellow warning lites on. Any help would be appreciated. codes on dash showing low voltage at dpf sensor.
Sounds like a DPF problem AND the air temp sensor needs calibrated.. Have you had the shop hook to the computer and look at things? I know the DPF will cause the engine to derate.
I think it's in the drivers side mirror. Last year on my Freightliner that sensor went bad and was telling the computer that it was 500 degrees when it was around -10. The computer didn't know to warm the DEF and the truck didn't like slushy DEF. It might just be that sensor. If the computer thinks it's hot, then that's the issue, maybe.
I think it goes to the body computer and that tells the ECM what the temp is. The gauges are on a multiplex system and that gets info from different modules like the body computer and the ecm. You may have to bring it to the dealer for them to "adjust" the body computer to read the new sensor.
according to the warranty just done on my FL. they hase to take the bumper off. tonreplace mine in order to make my ac work again.
Mounted behind the bumper, right side. Check the sensor voltage. Should be 5v. The sensor is connected to the sam cab and gets translated through the j1939 databus
I myself have a similar issue with the outside temperature sensor on my 06 Coronado. Readings are all over the place. I already replaced it twice and still the same. I wonder if it's a broken wire, or does the signal go to the ecm making bad contact with the plug and pins. Thanks for any suggestions.
there are few ambient air sensors in the truck. behind of bumper passenger side, in MCM, in ACM and one on frame(behind of drive axles, plastic sensor ziptie-d to air lines)..my truck is 2012 my. 2014 my had a sensor in mirror .
Mhyn, thanks for response. My sensor is behind the bumper on driver side. My question is, are the wires going to the ecm or firewall? I already checked the plug and it looks good. What's wierd is that with key on and truck off, temperature reads accurate. But, when the truck is on, temp goes crazy.
I guess the problem is not coming from sensor. SamCab could be faulty because that sensor is wired to samcab. Wiring diagram is needed for your truck to check it.
