NewAire External Temp Sensor

[jak2998]

My external temp sensor on my 2020 NewAire reads -40 degrees, which unfortunately turns on the block heater. I have pulled the fuse, but am worried my solenoid will still energize. I have asked Newmar for help locating the sensor and they pointed me to the front drivers side area under the headlamp. Unfortunately, it is not there. Anyone have any ideas where this is located?

[Bobby Dowdle]

That is where is should be located. Usually down low next to the frame around the genset. It is a 2-pin plug with a tip on the end. That is what you are looking for. You can turn off the breaker and unplug the block heater from the outlet to verify it won't energize. I will look to see if we have on the lot, but I don't believe we do.

[jak2998]

I did get a reply from Newmar and they indicated it may be inside the black chaffing wrap they put around the wire bundles. Our coach is currently in storage, so I will go look in the next few days. Obviously this makes it hard to see, or find, if it is inside the chafe wrap. I'll let you know what I find

[sramer]

On my London Aire it is a little probe that is zip tied to the bottom of the brace next to the windshield washer fluid bottle.

In case unplugging that does not work. The Silverleaf TM250 module is what controls it, try unplugging it.

On mine it's located on the rear wall that seperates the rear basement bay from the water tanks, mounted on the wall between the frame rails. Good luck.

[Memery86]

Originally Posted by jak2998

My external temp sensor on my 2020 NewAire reads -40 degrees, which unfortunately turns on the block heater. I have pulled the fuse, but am worried my solenoid will still energize. I have asked Newmar for help locating the sensor and they pointed me to the front drivers side area under the headlamp. Unfortunately, it is not there. Anyone have any ideas where this is located?

We are having the very same problem with our 2020 New Aire. Showing -40 degrees. Newmar recommended locating TM250 controller and unplug/plug back in. Location: driver’s side behind plexiglass fuse panel. Can’t find. If you find it, let me know. Ugh!

[jak2998]

Originally Posted by Memery86

We are having the very same problem with our 2020 New Aire. Showing -40 degrees. Newmar recommended locating TM250 controller and unplug/plug back in. Location: driver’s side behind plexiglass fuse panel. Can’t find. If you find it, let me know. Ugh!

So I did find the temp sensor. It is up front, drivers side, tie wrapped to the frame. It is hidden, however, by black wrap around wire chafe guard. Nest step is to look for the TM250 SilverLeaf module and try to unplug it and plug it back in. The temp sensor itself is spliced is spliced directly to a set of wires, so no option of unplugging there unless I cut the wires and re-splice them

[jak2998]

Originally Posted by Memery86

We are having the very same problem with our 2020 New Aire. Showing -40 degrees. Newmar recommended locating TM250 controller and unplug/plug back in. Location: driver’s side behind plexiglass fuse panel. Can’t find. If you find it, let me know. Ugh!

So, I went to our coach this morning and the only modules located behind the plexiglass are a TM 100 and a KIB box. There is a Temp input in to the TM 100, but it is not used.

So, not sure where the TM 250 is located. Also, having a hard time finding a part number for the OAT sensor.

[flyboy013]

In my coach, the TM-250 is located in the bay just forward of the pegboard compartment. Same bay as the Girard controllers.

The module is located on the aft wall between the two frame rails. This module has connections for both the bathroom and outside temperature sensors.

If you disconnect the sensor from the module (Temp1 & Temp2), the resistance should be 10K ohms at 70 degrees Fahrenheit. Temp1 should be the ambient temperature at the generator.

[jak2998]

Originally Posted by Memery86

We are having the very same problem with our 2020 New Aire. Showing -40 degrees. Newmar recommended locating TM250 controller and unplug/plug back in. Location: driver’s side behind plexiglass fuse panel. Can’t find. If you find it, let me know. Ugh!

I did find and replace the temp sensor, however I still have the issue and then some additional questions have arisen. Since it has been a while I will go through my problems again in this post.

Problem I am trying to solve is mainly chassis batteries draining. We do not have power at our storage facility so we keep it outdoors and rely on the solar panels to charge chassis and house. This worked fine until a couple months ago. When I stored the coach, I had been turning both house and chassis batteries off.

About a month ago, I went to the coach and chassis were dead. I replaced the batteries and noticed that the outside air temp now reads -40 and therefore turns on block heater. My assumption was this is what had changed and why the chassis were dead. Note: cord in engine compartment for block heater is NOT plugged in.

Until I could replace the temp sensor, I started leaving chassis batteries on and set the generator to come on with low voltage. I also added two additional solar chargers to the chassis batteries. I have gone back almost daily to see what has been happening and to take readings on the batteries and checking hours on the generator. I also pulled the fuse from the block heater circuit in the bedroom closet.

Yesterday, when I checked the coach, the batteries were OK, but the generator had run for an hour the day before, so continuing to use the generator to keep the batteries charged is not a long term option.

I replaced the temp sensor, yet it still reads -40 and block heater remains on. I did notice, however, when I turned on house batteries the temp sensor would read the correct temp and block heater would turn off. I do NOT believe this was the case until recently. IE requires house batteries to function correctly.

I have read other posts and most folks say to plug and unplug temp sensor at the TM250 box, but I have searched high and low and can't find the TM250. So, here are questions:

1) Should temp only be accurate with house batteries on? I do not believe this was the way it worked when we bought the coach.

2) Where is the TM250? We have a TM100 behind the plexiglass where many of the other electrical components are but it does not have Temp hooked up. I have also checked all the frame beams.

3) Where is the relay or solenoid for the block heater? I believe it is still drawing current and would like to pull it if I can

4) Are there any other items that come on at -40 that I need to disable if I can't get temp to read properly?

5) Any other ideas or thoughts?

I also have one more unrelated question, our engine normally fast idles after you start it. It will drop down to normal idle if I keep my foot on the brake, but if I remove foot from brake it returns to fast idle. I am told when you push and release brake it should go to normal idle. What should happen?

Now here is the odd part. Yesterday it was cold outside, in the 50's. When I started the engine, it never went to fast idle, it stayed at normal idle the entire time.

Thanks for your help with this

[Bram]

On my 2018 3343, the TM250 is behind the wall at the back of the main cargo bay. Passenger side, back end of aft slide out.

My engine will high idle when selected using the cruise control, or whenever the airconditioner is selected.

[Suburbazine]

High idle on a diesel will be it trying to start a DPF regen. High idle makes more heat to boost burn off. This will happen hot or cold, fresh start or not. Hitting the brake only idles down because it thinks you are going to shift into gear.


As far as the temp sensor goes... are you sure your block heater is 12v? Most diesel heaters are 120v and run off a circuit breaker. You may have pulled an unrelated fuse.

[flyboy013]

Problem I am trying to solve is mainly chassis batteries draining.

FWIW I’ve had the same problem for 5 years now. Chassis batteries would last about 3 days before needing to be charged. It hasn’t been much of an issue for me has I keep coach plugged in when not driving or boondockimg. My understanding is that this is pretty common, but it shouldn't be.

About a month ago, I went to the coach and chassis were dead. I replaced the batteries and noticed that the outside air temp now reads -40 and therefore turns on block heater. My assumption was this is what had changed and why the chassis were dead. Note: cord in engine compartment for block heater is NOT plugged in.

This is the most complexing part for me. I don’t understand why Silverleaf would be turning the block heater on. Perhaps a feature of a newer version of the system. I would snoop around the Silverleaf configuration to see if it can be turned off, but I don’t think this is causing a problem as Silverleaf is merely activating the relay and since you do not have shore power the block heater doesn’t turn on.

I replaced the temp sensor, yet it still reads -40 and block heater remains on. I did notice, however, when I turned on house batteries the temp sensor would read the correct temp and block heater would turn off. I do NOT believe this was the case until recently. IE requires house batteries to function correctly.

It sounds like the TM-250 (wherever it is) is getting its power from wrong side of the house battery disconnect. Silverleaf typically gets its power from the input side of the disconnect such that it stays powered on when house battery’s are disconnected. Additionally the Silverleaf modules typically share the same 12V wire, so it’s odd that it would be powered differently.

1) Should temp only be accurate with house batteries on? I do not believe this was the way it worked when we bought the coach.

It should work all the time.

3) Where is the relay or solenoid for the block heater? I believe it is still drawing current and would like to pull it if I can

In the past this has been mounted at the main breaker box. Recommend having someone activate the block heater while you listen for the relay clicking. I do not believe this is your power draw as it’s a 120V AC device.

[jak2998]

Originally Posted by Bram

On my 2018 3343, the TM250 is behind the wall at the back of the main cargo bay. Passenger side, back end of aft slide out.

My engine will high idle when selected using the cruise control, or whenever the airconditioner is selected.

Bingo on TM250 location. Once you remove the panel it is right there, along with a fair bit of other wiring and components. I did remove temp sensor connection and plug it back in and that did not fix it. With some additional troubleshooting, it is clear the TM250 is not getting power when the house battery disconnect switch, right inside the door, is pressed. There is a KIB switch the manages power distribution to many of the components in that area. The main SilverLeaf touchscreen does continue to get power through the KIB switch when house batteries are off, but the connection right next to it, which feed the TM250 turns off. Not sure if KIB switch is bad. If it isn't too expensive, I will likely replace it.