8.3 ISC Cummins Grid heater Relay

[Bill Hines]

On my 2000 Dynasty 34 York Mh when starting, the grid heater solenoids are not engaged before starting. Wire #41 and #31 are not powering the relay. Trying to chase down where the wires go. Hopefully they could be disconnected or dirty and simple fix. I have a part#3408346 for Temp sensor for grid heaters.  The photo shows wire #41 and #31 attached to grid heater relays. They exit through top of compartment. The engine starts easy because I live in Florida, but in cool or cold weather it’s not happy for about 60 seconds and I generally turn on block heater hours before starting to over come grid heaters not functioning. Any help is greatly appreciated. 

Thanks

Bill

[Dr4Film]

Bill,

Van Williams is a member here who also owns a 2000 Dynasty. Why not send him a private message to see if he can help you resolve this problem.

His handle is Vanwill52.

Edited February 27, 2022 by Dr4Film

[jacwjames]

I looked on my chassis wiring diagram and at the Cummins Quickserve site.  The quickserve site has a wiring diagram that shows the interaction between ECM and OEM wiring harness.  https://quickserve.cummins.com/qs3/portal/service/index.html 

The chassis wiring harness shows the VSS directly controlling the Grid Heaters. 

Grid heaters will come on when the ambient temps outside is low enough for the ECM to send the signal to the VSS and sends signal for the grid heaters to come on.

How cold is it where you are, I'm not sure at what temp the grid heaters actually work!  

[Ivylog]

If a “wait to start” light doesn’t illuminate, it’s probably not powering the grid heaters because they are not needed. Have they ever worked?

[Bill Hines]

 The “wait to start” light comes on ever time during pre-start, but grid heaters never engage. It’s never worked since I bought the MH in 2013. I’ve used block heater to preheat engine prior to starting. Van Willams had this problem in 2015 and he checked all connections in engine room area which ended up resolving the problem. I clean engine room today so I have a “clean environment “ to start to trace down the connections. The temp here is not cold or cool so not sure how to confirm if it’s working. Thanks for the help. I will follow up with what I find so it might help some in the future.

[Rocketman3]

I only have those heaters turn on when it’s cold - starting the motor in the 30’s. When it turns on the chassis volts drop - the alternator volts we’re cycling from 14 down to 11-ish up and down every 15 seconds (as I remember). Kinda freaked me out the first time. 
 

they never kick on except when it’s cold. 

[Bill Hines]

The problem that I’ve experienced is rough to non starts in cold weather. I live in Florida so cold weather is not an issue here. But when we travel to other areas it will get cold and there is the problem. I’ve over come rough starts by turning on block heater and all is good. 

I’ve never heard the grid heater solenoids engage when key is turned and waiting for “wait to start” light goes out. I have hooked up power to solenoids and they do click and engage the grid heaters. Wire #41 and #31 which I traced back to the ECM on the engine. When I disconnected 41,& 31 and hooked up a hot wire everything works. Engine starts strong runs smooth. 

Now I have read different post where the grid heaters don’t engage until it’s 50 degrees and Rocketman3 suggests at 30 degrees. 

The ECM is recognizing the grid heater solenoids were disconnected send a warning to dash and silver leaf.

This is the error screen on tablet that runs sliver leaf: ( warning light went off)

[jacwjames]

I wonder if you have something going on with the ambient air temp sensor.  I believe this is what sends the signal to the ECM which in turn initiates the grid heaters.  But I would have thought if there was something wrong with the sensor the ECM would flag it.

On my rig the sensor is located above the starter. 

[Bill Hines]

That’s kind of where I going with my problem. I saw 3 senders and removed and spayed cleaner and reconnected. One of the plugs seemed damaged. I will go back and try to identify the sender

[Bill Hines]

I think I’ve narrowed it down to the air temp sensor. Found it just as jacwjames said. On the sensor 10703 number cross reference 4928386 part number. Quite pricey too. eBay has one for $249.00 ahhh.

So I believe I have a bad temp. Sensor. 

[jacwjames]

Are you sure this is the right sensor???

Mine is different 3085140 based on the list of ECM sensors I downloaded from Quickserve.  Here's an older thread from IRV2.  https://www.irv2.com/forums/f115/where-is-the-barometric-air-pressure-sensor-located-390403.html    look at post #19

https://www.ebay.com/sch/i.html?_from=R40&_trksid=m570.l1313&_nkw=4902720+cummins&_sacat=0

Using my part #

https://advancetruckpartsusa.com/products/3085140-cummins-pressure-sensor

Seems like the supply chain issues are hitting our pocket books harder if that is the right part!!!!!!!!!

 

Cummins ECM sensors.pdf

[Bill Hines]

Jim,

I’m not sure. Back to the Engine Room. I’ll look for the sensor above lift pump.

Maybe disconnect and see error code on Silver Leaf if that can tell me also.

Thanks 

 

[vanwill52]

I cannot add much to this conversation, as I have never had problems with the grid heaters, at least not that I was aware of.  I have never had reason even to verify that they are working.  What I can say is that my "Wait to Start" light comes on EVERY time I start the engine, regardless of ambient temperature...it comes on even in the hottest days of summer.  I have (8) coach batteries (T-145 size, not the smaller T-105) with a total of approximately 1000 AH.  My engine batteries are two Group31 batteries (950 CCA each) paralleled together and using all 4/0 cables.  I also have a Denso gear-reduction starter, so the engine spins over MUCH faster than with the original Delco direct-drive starter.   I also have the Blue Sea ML-ACR setup, so that I always start the engine in "Battery Boost" mode.

Purely out of curiosity, during a spell of exceptionally cold weather here, I have started the engine by turning the key to start position immediately without waiting for the grid heater "Wait to Start" light to go out when ambient temperature was mid-20's.  It fired up instantly, and I could not detect any difference in how long it rolled over before starting.

Although I have never had a failure to start, I installed the Denso gear-reduction starter because with the original Delco straight-drive starter, it always seemed to me that the engine just barely rolled over fast enough to start, even when waiting for the "Wait to Start" light to extinguish.  My conclusion (not necessarily scientific) is that if the engine is turning fast enough with the starter, it will start regardless of temperature.  I THINK not all Cummins engines have grid heaters.

[Bill Hines]

I found it. Above lift pump. 😀 Now how can I check to see if it’s operating correctly?

Thanks for the IRV2 forum link and to everyone, this has been a long journey. 
7

[Ivan K]

I am following this thread out of curiosity even though my engine is different. Why did the discussion turned to a pressure sensor that has little to do with temperature? Anyway, when I wanted to see whether the ambient pressure sensor works, the only way I know was to compare it's reading to my Kestrel readings over number of days to see if they move the same direction with changing weather. And I could only see it through Insite. Don't know about silver leaf and such since I don't have it.

[jacwjames]

Here is a trouble shooting guide for the Ambient sensor, I downloaded this off the Cummins Quickserve website. 

I tried using the displayed fault code you posted on the Quickserve site but it does not recognize it for my engine.  Do you have an account on the Cummins site, if you do try using the Fault Code Search tool under the Service tab.   In your case it should be SPN 237 FMI 11 but nothing comes up when I try the search but it may not be coded to my SN engine.   Need to try and access the Quickserve site for your engine and run the fault code search before going any further. 

The 221 fault code below translates to a SPN 108  FMI 3

FAULT CODE 221 - Barometric Pressure Sensor Circuit - Voltage Above Normal or Shorted to High Source.pdf

Also, you may want to confirm that you have selected the correct engine why you set up the Silverleaf, check under Advanced/Engine type at the top of the display page.

Edited March 4, 2022 by jacwjames

[frank@fpexton.com]

I have a 2000 Windsor with the grid heaters and live in WY.  I've had it for 10 yrs and the "Wait to start" light has never come on, but I've never had any trouble starting it until last year and now no matter what the temperature is, cold or hot it it spits and sputters and completely engulfs the coach in white smoke. So I'm interested in this subject. I haven't taken the time to figure out why the grid heaters aren't working.

The ambient air  sensor on my truck "Cummins ISX" just hangs on the harness, but it is  a 2010. Also a Barometric pressure sensor senses your barometric pressure (altitude)and keeps your engine running right whether you are at sea level or the top of a mountain.. That last picture you posted Bill looks like a barometric pressure sensor. There should be a part number on it if you can get it out. I know with my trucks , if you take it to the shop, they don't bother to test them, (all sensors) they just tell you to change them out. Easy for them to say that when it's not their $250. You could probably check continuity of your wires to the relay to see if that's the right sensor.

[frank@fpexton.com]

After looking on Quickserve, it might be the "Intake Manifold Temperature sensor" that controls the "Cold Start Aid  Circuit". I've attached a Quickserve 019-164 procedure that shows how to check the wires. Looks like 3408346 is the right part number.

Cold Start Aid.pdf

[frank@fpexton.com]

Here is a general information file on the cold start aid. The graph shows intake and coolant temperatures sensor averages. That's why I am thinking maybe the intake temperature sensor is the one.

010-029 Cold Start.docx

[Bill Hines]

Thanks Frank,

Thats what I’m looking for “ intake Air Temp. Sensor”. ( or what triggers wires #41 and #31 on relays coming from ECM.)

Also I’m not getting any codes that I haven’t caused by disconnecting wires.

1.“Wait to Start “ Works 

2.ECM knows wire #41 and #31 are connected to heater grid relay. I know this because when I disconnected these two wires, a error code came up on silver leaf (code 237) plus warning light on dash. Hook the wires back up error is gone and warning light is off. 

3. Hooked up power to where #41 and #31 wires are connected on grid heater relays and they engaged. 

I’m trying to understand what it is that tells ECM to engage grid heater relays. If it’s a sensor where is it and whats the part #? 

I able to start in cold weather the few times I need too by using block heater. I want to understand  how it works.  I don’t like the rough start and smoke when engine is cold and I forgot to turn on engine block heater or I’m dry camping.

Maybe I’m not understanding about ambient pressure sensor to do with grid heater? 

 

 

 

[Ivan K]

Does your silverleaf show intake manifold air temperature to compare to ambient while cold and see if it shows correctly? If it does, then it makes it to the ECM just fine.

This may not help but if there is any similarity to ISM, my sensor is on top of intake side by the inlet pipe and is also called 'boost temp' sensor.

Edited March 6, 2022 by Ivan K

[jacwjames]

I'll back up and say that the ambient air pressure doesn't have anything to the grid heat.  Sorry for sending you down that rabbit hole.

 

There is a sensor for the air temperature, 3408346  http://en.gasgoo.com/showroom/vowdo-auto/auto-products/2903727.html

I've tried to find where it might be located and I have not found it shown in any of the service manuals I have in my files and have yet to find mention of it.  Have not found any troubleshooting information on it that shows location.

Makes sense that it is located in the air intake system.  First chance I get I'm going to look at my engine intake and see if I can identify. 

[jacwjames]

OK, I went out to the coach today and did some poking around.  I found 2 sensors on passenger side of the engine below the air intake. 

The first picture is right below the intake.

The second picture is a little towards the rear of the engine closer to the transmission. 

Also attached is a description of the engine that I had downloaded from the Quickserve site a while back, it does list the air temperature sensor which I believe is in the first picture since it is a two wire sensor.  You can see the ECM below it.

I believe the second picture is of the air pressure sensor this is a 3 wire sensor.  

It does not give precise location of either sensor. 

Cummins Engine description in detail.pdf

Edited March 6, 2022 by jacwjames

[frank@fpexton.com]

Bill,

The 41 and 31 pins are on the oem side of the ecm, not the Cummins side. So the wiring diagrams in Quickserve are only for the Cummins side and I can't tell which temp sensor the ecm uses to signal the grid heaters on. Should be the intake air temperature which I think is the one in jacwjames'  first picture. It should be in the cavity right below the grid heaters, which is the intake. I think that part number that James gave you is right too. Like they said if you're showing a code when it is disconnected then I think your wires and connections are fine, the sensor isn't sending a temperature to ecm. I'd try to buy one through a Cummins dealer or truck dealership and if they have it in stock, they might let you change it out and see if it fixes the problem. 

You're right the air pressure doesn't have anything to do with the grid htrs. 

Frank

 

[pwhittle]

13 hours ago, jacwjames said:

I'll back up and say that the ambient air pressure doesn't have anything to the grid heat.  Sorry for sending you down that rabbit hole.

 

There is a sensor for the air temperature, 3408346  http://en.gasgoo.com/showroom/vowdo-auto/auto-products/2903727.html

 

That listing references OE Part number 3408345, which shows up on The Cummins site.

 

That part number is available from various sources, including Cummins, Amazon, and eBay for prices ranging from under $20 to $45 from Cummins.

Paul