how to fool ambient temp sensor to run heater

[gltrimble]

Hey there ncv3 folk... Pretty nifty and straight forward mod you guys came up with here. Some of the t1n folks have a thread going to replace the existing factory d5 heater with a new one but the new one has an ambient >39f ambient temp lockout like your factory d5 furnaces do. This resistor should work just as well for us as it has for you, but some of us want to use the furnace with engine off and there’s speculation as to whether it will work without the ecm being on to interpret the sensor information and then broadcasting it over the k line to the heater. It appears some of you are running the furnace with engine off. Does this mean the ecm doesn’t need to be powered on to interpret the ambient temp information and then broadcast? Doesn’t appear anyone is powering on the ecm with the engine off to get this mod to work with the engine off. Perhaps ncv3 and t1n Sprinters are different in that the ecm is always interpreting sensor information (we haven’t tried this so I’m not suggesting this is the case)? Perhaps ours will work just as yours and we don’t need to power on the ecm??

The factory H12 Espar D5 is intended to operate with the engine off. The ignition key does not need to be in the ignition. Not much need for the D5 if the engine is running other than to bring it up to temperature quicker. Be aware once the engine coolant reaches a minimum temperature the factory D5 will not operate.


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[vanski]

And just to confirm, the h12 option d5 is on the resistor?

 

[gltrimble]

The resistor intercepts the ambient temperature probe using a DPDT switch. The resistor fools the ECM into thinking it is 18F so the D5 will operate.


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[Racrx]

Thanx for this! Put my sensor in ice as the temp has been too warm to fire the booster up, took a few button pushes but it finally fired (it hasn’t run since winter).

 

[Mickyfin]

The factory H12 Espar D5 is intended to operate with the engine off. The ignition key does not need to be in the ignition. Not much need for the D5 if the engine is running other than to bring it up to temperature quicker. Be aware once the engine coolant reaches a minimum temperature the factory D5 will not operate.


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This is correct. Mine has the H12 system, and its great for preheating the engine coolant when we have -35c during winter, it also blows warm air into the cabin, defrosting the screen. It shuts off automatically once up to temp.

 

[Neil2]

How do you "look to see that both Espars are running"? I've got two factory D5 Hydronics and it never sounds/seems via heat output) that both are running and I've had multiple peeps say they suspect the second only kicks in if it's super cold and the engine 'needs' the second to reach temp.

 

[RVBarry]

22k ohm resistor ( 5* F ) - aux heater will turn off after 40 min.
10k ohm resistor ( 31* F ) - aux heater will turn off after 20 min.

I settled on a 15k resistor which gave me 40 minutes of run time on the OEM D5 up to three times for a total of 120 minutes. 15k equates to 18F. In most cases 40 minutes is enough to heat my Isotemp 4+ gallons. Cold weather, below 40F, might require a second 40 minute operation.

Why not put a resistor in series on one leg and use a switch as a shunt?

My apologies for the kindergarten style MS Paint schematic. The general range 15 K resistor is a guess based upon the 22 K being reported as a low spoof. Again, the resistor value/resulting specific temperature is not necessarily critical for monthly test operation. It needs to be low enough.
vic

Hi, is Vic's diagram going to work well?
I get that it'll work when the switch is open; the ECU will think it's cold enough to run the heater.

But in normal (closed) operation, the new resistor in parallel will skew the temperature reading, right? Perhaps significantly?

Anyone have a resistance chart for this or a similar temperature sensor?
I'm seeing some that increase in resistance as temperature goes up, but most appear to decrease.

This may be a bummer as I ordered a custom Carling switch (ST, with a second circuit to turn on a LED) that took many weeks to be made and delivered.

 

[vanski]

I’d think (never tried it so don’t know for sure), yes the temp reading will be skewed..

Why not use a normal auto relay with sp switch or even a dpdt switch? Probably other ways to separate the circuits in addition to above..

 

[RVBarry]

I’d think (never tried it so don’t know for sure), yes the temp reading will be skewed..

Why not use a normal auto relay with sp switch or even a dpdt switch? Probably other ways to separate the circuits in addition to above..

Yeah, looking for a Carling DPDT, with a light, now.
edit: in-stock (blue or white LEDs) at https://www.otrattw.net/v-series-sealed-rocker-switch-body-only-no-rocker-vjd2uxxb1.html

A friend just suggested that a SPDT would suffice (instead of a DPDT) if I weren't wanting a lighted indicator switch:

Either layout should work, and only needs 3 wires instead of the 4 that a DPDT would need.

Also considering putting a Bosch SPDT relay under the hood and using the switch I already got.
(although the switch would be more reliable, as I'm getting power from the EK1 terminal which might turn off after a few hours.)

 

[RVBarry]

Here's a diagram using a DPDT w/ a LED/light (such as this Carling switch):


Again, 3 wires (in bronze) need to be run to the grille.

 

[RVBarry]

Anyone seen a male connector plug that would fit in the ambient temperature sensor socket?

Part numbers for the female socket are at

ISO Temperature sensor M&F connectors (MB / TE / AMP)

Hi, The ambient air temperature sensor in the VS30 grille plugs into a female TE Connectivity 1-1418463-1 socket, aka MB part A 006 540 17 81. Anyone know where to find the # for a matching female connector? (not the sensor itself; I'm trying to make something) Here's a source for the male...

sprinter-source.com

Hi,
The ambient air temperature sensor in the VS30 grille plugs into a female TE Connectivity 1-1418463-1 socket, aka MB part A 006 540 17 81.

Anyone know where to find the # for a matching female connector? (not the sensor itself; I'm trying to make something)

Here's a source for the male:

TE Connectivity 1-1418463-1 A 006 540 17 81 2POS MQS REC SEALED COD A X113086

TE Connectivity 1-1418463-1 in stock, at a great price, with a 30-day warranty and fast USA shipping.

teamequip.com

Also here, but 'restricted'

1-1418463-1

Get 1-1418463-1 specs, pricing, inventory availability, and more from TE Connectivity. Get a sample or request a quote.

www.te.com

The MB p/n (for the female connector) is listed online as 'clutch'.
Perhaps a clutch pedal switch?

Thanks!

 

[RVBarry]

Do you guys close all the vents when heating your Isotemps with the H12? (could that overheat the blower motor?)

I can't see a way to turn the dash blower off, nor change the heat temperature setting.
Thanks

 

[RVBarry]

Anyone seen a male connector plug that would fit in the ambient temperature sensor socket?

I found a video on YT by RandomFix, where he cut open a spare temp sensor and added the new wiring to it.

I'm not sure that looks reliable.

Anyone have an idea for the compatible male plug?
I did email TE yesterday, hopefully they'll get back to me next week...

 

[RVBarry]

10k ohm resistor ( 31* F ) - aux heater will turn off after 20 min.
22k ohm resistor ( 5* F ) - aux heater will turn off after 40 min.

For those that have inquired offline, I settled on a 15k resistor which gave me 40 minutes of run time on the OEM D5 up to three times for a total of 120 minutes. 15k equates to 18F. In most cases 40 minutes is enough to heat my Isotemp 4+ gallons. Cold weather, below 40F, might require a second 40 minute operation.

BTW, I noticed when testing with ice water (32-35℉) that my VS30's H12 runs for about 45 mins.
Not sure how long it'd run on a colder reading, but I think I'll look for a 10kΩ resistor.

 

[RVBarry]

Anyone seen a male connector plug that would fit in the ambient temperature sensor socket?
Part numbers for the female socket...

I found multiple compatible parts; they are all listed at

ISO Temperature sensor M&F connectors (MB / TE / AMP)

Hi, The ambient air temperature sensor in the VS30 grille plugs into a female TE Connectivity 1-1418463-1 socket, aka MB part A 006 540 17 81. Anyone know where to find the # for a matching female connector? (not the sensor itself; I'm trying to make something) Here's a source for the male...

sprinter-source.com

The short version is that the full set from eBay is good and cheap, but not fast:

2 Pin TE Automotive MQS Male Female Connector Plug Socket Kit For BMW Land Rover | eBay

Quantity Selection: 1/5/10 Set (Menu options) Package minimum includes 1 SET: 1 x Male Connector Housing 1 x Female Connector Housing 2 x Male Terminal 2 x Female Terminal 4 x Rubber seal AC0570.

www.ebay.com

 

[RVBarry]

I updated my other thread re the connectors, adding assembly notes and pictures...

teaser:

ISO Temperature sensor M&F connectors (MB / TE / AMP)

Hi, The ambient air temperature sensor in the VS30 grille plugs into a female TE Connectivity 1-1418463-1 socket, aka MB part A 006 540 17 81. Anyone know where to find the # for a matching female connector? (not the sensor itself; I'm trying to make something) Here's a source for the male...

sprinter-source.com

I put the resistor (12k Ohm) on the switch output itself, to the white wire (not pictured).
edit: dash shows 24 degrees F with the 12k resistor activated (2023 Sprinter)

 

[RVBarry]

Do you guys close all the vents when heating your Isotemps with the H12? (could that overheat the blower motor?)

I can't see a way to turn the dash blower off, nor change the heat temperature setting.
Thanks

bump...

 

[Wrinkledpants]

I've heard that if you recode the cluster from US to Canada, you gain the ability to run the D5 at any temp, and you gain the ability to turn off the daytime running lights. Not that you'd want to do this on the regular, but say you're in camp and idling a bit.

Has anyone tried this who has the equipment?

 

[Kajtek1]

I've heard that if you recode the cluster from US to Canada, you gain the ability to run the D5 at any temp, and you gain the ability to turn off the daytime running lights. Not that you'd want to do this on the regular, but say you're in camp and idling a bit.

Has anyone tried this who has the equipment?

I could do such thing on older ML with W163 body, but don't see such option on newer MB.
The option also reset odometer to km and temperature to C.

 

[Wrinkledpants]

I could do such thing on older ML with W163 body, but don't see such option on newer MB.
The option also reset odometer to km and temperature to C.

You need the computer setup that allows you to program various modules on the van, and access the cluster to hard-code that. This isn't something you can do natively through the menu.