2021 Stop Sale on certain diesels incoming (intake air heater relay). - Recall Y76 REFRESHED OCT 2021

[wolfpack]

So, as an EE, could you calculate the heat sink requirements for a 110

So, as an EE, could you calculate the heat sink requirements for a 110 Amp, 12V SSR?

Nope. My chips have a supply voltage of 0.8V and current draws around 0.1A

Different world. But the principles are the same. Current flowing through metal causes the metal to migrate in the direction of current flow. Thus a “wire” of a given geometry has a maximum current it can carry before it will begin to fail. That maximum de-rates by a factor of 2 for every 10 degree Centigrade rise in temperature. It’s brutal.

 

[Brewbud]

The big concern is they mention it can fail in the key-off position. So it is not something just sticking on. Sounds like it is an electrical breakdown of the insulation. It could be their potting material was compromised by a supplier who substituted a material in the compound because of limited supplies. Heck even not cleaning a subsystem correctly before potting can lead to electrical breakdown. All just assumptions but these things have happened in other devices.

 

[ColoMike]

I wonder if hot glue could be used as a potting compound rather than RTV sealant on the back of this relay? Probably not, as RTV has a much higher melting point.

 

[rfullen280]

Nope. My chips have a supply voltage of 0.8V and current draws around 0.1A

Different world. But the principles are the same. Current flowing through metal causes the metal to migrate in the direction of current flow. Thus a “wire” of a given geometry has a maximum current it can carry before it will begin to fail. That maximum de-rates by a factor of 2 for every 10 degree Centigrade rise in temperature. It’s brutal.

Interesting, so... at some particular current amount, the molecules of the wire itself start to "move" in the direction of current flow. Basically, they self-weld? That does sound rough... I assume that's a pretty large current for say, a 2-AWG wire?

 

[unclelala]

Man all this science for a recall !

 

[wolfpack]

I wonder if hot glue could be used as a potting compound rather than RTV sealant on the back of this relay? Probably not, as RTV has a much higher melting point.

I think they just messed up on this one. Adding more volatile organic compounds to a heat source increases fire risk. There’s no way out other than a bigger relay with more heat-sinking. The thing is just too hot.

 

[Brutal_HO]

I think they just messed up on this one. Adding more volatile organic compounds to a heat source increases fire risk. There’s no way out other than a bigger relay with more heat-sinking. The thing is just too hot.

I don't think I've every heard of a pre 19 truck heater grid relay catching on fire.

I get that the old ones are electromechanical, <rhetorical> but why'd they have to go mess with something that ain't broken? </rhetorical>

 

[Robtheelder]

Interesting discussion.
I have been doing some research and have found what seem to be reliable sources that indicate the draw is 250 amps peak and around 200 amps once the grid temperature stabalizes.

The fact that it can cause a fire whilie "off" suggests that the issue is an internal failure in the relay that allows formation of a current path even when the relay is not energized. What happens then is the two on board batteries attempt to supply infinite current instantaneously . A good outcome in that case is the thermal causes an interruption in the current path and the event ends. Worst case is it continues long enough ignite combustaqble material in the area. I had a battery cable on my trailer short to ground and it created a fire in the insulation that required application of an extinguisher to get under control as well as interruption of the current path. In the engine bay of the truck, there are a number of fuel sources for an electrical fire that can spread quickly.

My truck is July 19 21 build and I have an appointment to have the recall done in about a week. Probably they will take the relay temperature and verify that there is nothing obviously amiss and send me on my way.

It seems like long term the answer is to replace the grid heater with a throttle body heater.

I have a smart switching device on my block heater and dual battery heaters. I think I will add a heater blanket for the intake so when the truck is cold soaked, it will not feel the need to turn on the grid heater for an extended eriod of time.

I enjoyed a video of a grid heater delete yesterday. AFter 70k miles the intake side of the grid heater looked like the firebox on a steam locomotive that has gone too long between cleanings. Really ugly. Not liking that.

 

[wolfpack]

I’ll bet what’s going on with the ignition-off fires is that the overheated relay has probably already melted its plastic holder and shifted enough where the backside of the terminal lugs can touch the chassis.

My 2021 so far looks pristine but I live in central NC and took delivery of the truck in July. I’ll bet the grid heater hasn’t come on once since I’ve owned it.

 

[Worf_359]

I enjoyed a video of a grid heater delete yesterday. AFter 70k miles the intake side of the grid heater looked like the firebox on a steam locomotive that has gone too long between cleanings. Really ugly. Not liking that.

I wonder if that's what the 600 hr thing is about. Wonder if it does some sort of cleaning cycle by then where the heater is on long enough to burn off any carbon deposits. (and the rest of your engine bay, if the relay fails then.)

I just joined over this issue, seems a clear case of adopting new technology before it's proven. I'll be taking my truck to the dealer, but will be swapping to a mechanical relay afterwards.

My guess is the fact that the intake heater "cycles" when ambient temps are low means they were either starting to have issues with the mechanical relay wearing out, or were concerned about that. Only get so many cycles out of a mechanical relay, and increased number of cycles between failures are a big reason why SSR's are a thing. That being said, swapping out the mechanical relay is easy given it's location in the engine bay, and immensely preferable to a fire.

Ram should just abandon the SSR till they've worked out the kinks, and a return to the mechanical relay should be the fix. I know I can't trust their SSR designs anymore, two separate issues in a year? That's a sign.

 

[CdnHO]

Interesting discussion.
I have been doing some research and have found what seem to be reliable sources that indicate the draw is 250 amps peak and around 200 amps once the grid temperature stabalizes.

The fact that it can cause a fire whilie "off" suggests that the issue is an internal failure in the relay that allows formation of a current path even when the relay is not energized. What happens then is the two on board batteries attempt to supply infinite current instantaneously . A good outcome in that case is the thermal causes an interruption in the current path and the event ends. Worst case is it continues long enough ignite combustaqble material in the area. I had a battery cable on my trailer short to ground and it created a fire in the insulation that required application of an extinguisher to get under control as well as interruption of the current path. In the engine bay of the truck, there are a number of fuel sources for an electrical fire that can spread quickly.

My truck is July 19 21 build and I have an appointment to have the recall done in about a week. Probably they will take the relay temperature and verify that there is nothing obviously amiss and send me on my way.

It seems like long term the answer is to replace the grid heater with a throttle body heater.

I have a smart switching device on my block heater and dual battery heaters. I think I will add a heater blanket for the intake so when the truck is cold soaked, it will not feel the need to turn on the grid heater for an extended eriod of time.

I enjoyed a video of a grid heater delete yesterday. AFter 70k miles the intake side of the grid heater looked like the firebox on a steam locomotive that has gone too long between cleanings. Really ugly. Not liking that.

Even if my relay passes, I intend to replace it once the part becomes available. In the meantime I will check to see if the one I have now gets hot when the grid is on. If it does I will disconnect the feed from the battery.

 

[WisHawk]

Checked mine yesterday looks fine up to this short time since new.
My build date was 6-3 I have AA part number.
It won't be long and before the cold weather is here to stay in the upper mid-west.
I must post correction. Build date was 5-13 -21 ( Realized the date I was looking was date of download. Sorry for placing the wrong date in my initial posting.)

 

[DasBoot]

My 3-21 build 2500 also has the AA relay. My southern OR dealer informs me that nothing can be done until FCA issue the replacement/fix in Feb 2022.

 

[Cturner]

Checked mine yesterday looks fine up to this short time since new.
My build date was 6-3 I have AA part number.
It won't be long and before the cold weather is here to stay in the upper mid-west.

That's interesting...my build date is also 6-3, but I have the AB relay.

 

[diesel_driver_3500]

For those speculating on how many amps the relay/heater draws, looks like it's fused to 250 amps. I realize this is not the lug that attaches to the relay, but the two look the same and I would bet they are.

 

[cycling4life]

Are there any long term effects of NOT having the grid heater while the relay is disconnected for those of us that live in a state that has strict emissions requirement?

 

[unclelala]

Just found mine...build date July 21 2021 and the relay is AB

 

[CdnHO]

Are there any long term effects of NOT having the grid heater while the relay is disconnected for those of us that live in a state that has strict emissions requirement?

Unless it is really cold, it may turn over a couple more times before firing, but I don't think there is any downside to disconnecting the relay battery terminal.

 

[Worf_359]

Unless it is really cold, it may turn over a couple more times before firing, but I don't think there is any downside to disconnecting the realy battery terminal.

I'm wondering, based on the presence of an EGR system upstream of the heater, and the 600 hr note with the 2022 trucks, if there's a cleaning cycle to try and burn off the carbon deposits on the intake heater...

Pure conjecture, but that's the only potential issue I see. I want the Banks intake plenum ASAP anyway, so that's my intended fix if this concern turns out to be an issue.

 

[wolfpack]

For those speculating on how many amps the relay/heater draws, looks like it's fused to 250 amps. I realize this is not the lug that attaches to the relay, but the two look the same and I would bet they are.

View attachment 24382

Arc faults that don’t exceed the fuse or breaker limits start fires as reliably as a match and gasoline.