Flashing check engine light

[Almost 13ranch]

2016 Ram 2500. I have noticed, especially when it's very cold out that the check engine light, that comes on and stays on at other times until starting, is now flashing while waiting for the grid heaters to warm up. In both cases, the light goes out after starting.

Any insight as to why this is happening?

 

[SnoKing]

How old are your batteries?

 

[Almost 13ranch]

Batteries replaced 3 months ago.

 

[Topzide]

Have you noticed a battery saver mode message in the EVIC? Could be enough draw down on then and charging has to wait till they warm. Have you pulled any codes? Might be time to invest in AlfaOBD to read and diagnosis codes. Little more info on how cold? I hooked up a maintainer after getting battery saver mode when the cold spell hit us on the east coast. Wired it through the 7 way trailer connection. That way don't have to open hood to hook up or disconnect!

 

[Almost 13ranch]

I haven’t seen a battery saver mode message in the EVIC. There are no stored messages. I just now scanned for codes with the reader I have and there are none stored or pending.
The temperature I’ve noticed this before was about +20° F. When I just went to scan for codes it was 36°F.
It showed the grid heater light and the MIL light was on steady, then it flashed maybe 10 times and then when steady again. It went out when I started the truck, like it usually does.

 

[Almost 13ranch]

How old are your batteries?

I wonder if I should load test them. I have a friend that’s had 2 brand new Interstate batteries fail in 7 months. The batteries I have are Interstates.

 

[Almost 13ranch]

First off, is it normal for the MIL light to stay on after the POST until it’s started? My 2015 does the same thing. I never saw that before on my 2000.

 

[Topzide]

My 2014 Mil stays on till started. Wouldn't be a bad idea to get them load tested. Anything can have issues right out the box!

 

[Almost 13ranch]

So, the MIL light coming on before starting is normal. Does the flashing light lead you to believe that there is a possible battery or voltage issue? Would it be linked to the lower ambient temperature and the activation of the grid heaters?
I do know that my old 2000 would heat the grid heaters for a lot longer than this truck.

 

[PRS]

So, the MIL light coming on before starting is normal. Does the flashing light lead you to believe that there is a possible battery or voltage issue? Would it be linked to the lower ambient temperature and the activation of the grid heaters?
I do know that my old 2000 would heat the grid heaters for a lot longer than this truck.

So the MIL comes on for a check and then if all is ready for an emissions test, the light will remain steady until it starts and the light goes out. If the light flashes, one or more monitors are not set. Normal driving is supposed to set the monitors. This is all explained in the manual, however when I talked with the dealer about mine flashing they were clueless. They eventually set and it quit flashing but it took many drive cycles and miles.

 

[Almost 13ranch]

So the MIL comes on for a check and then if all is ready for an emissions test, the light will remain steady until it starts and the light goes out. If the light flashes, one or more monitors are not set. Normal driving is supposed to set the monitors. This is all explained in the manual, however when I talked with the dealer about mine flashing they were clueless. They eventually set and it quit flashing but it took many drive cycles and miles.

I don’t remember the light flashing when I first got the truck in August. What are the monitors in reference to? I guess I’ll look in the owners manual for the explanation, I must have missed it before.

 

[Almost 13ranch]

So the MIL comes on for a check and then if all is ready for an emissions test, the light will remain steady until it starts and the light goes out. If the light flashes, one or more monitors are not set. Normal driving is supposed to set the monitors. This is all explained in the manual, however when I talked with the dealer about mine flashing they were clueless. They eventually set and it quit flashing but it took many drive cycles and miles.

By manual, do you mean the owners manual or the Factory Service Manual?

 

[PRS]

By manual, do you mean the owners manual or the Factory Service Manual?

Owners manual.
There are some scanners that will show you the monitor status. OBD link that comes with the MX+ is one that I use.

 

[Almost 13ranch]

I found the reference for the flashing light in the owners manual, I'm not sure if I need to go to the dealer for diagnosis though.

I rescanned with my reader and here are pics of what it showed. The last one is just to show the legend.



I also used my cheap load tester on the batteries and they both showed weak. I think I'll go to the parts store I bought them and have them use their fancy tester on Monday.

 

[PRS]

I found the reference for the flashing light in the owners manual, I'm not sure if I need to go to the dealer for diagnosis though.

I rescanned with my reader and here are pics of what it showed. The last one is just to show the legend.

View attachment 132772 View attachment 132773 View attachment 132774

I also used my cheap load tester on the batteries and they both showed weak. I think I'll go to the parts store I bought them and have them use their fancy tester on Monday.

Make sure your batteries are fully charged when you do the load test. I'm guessing they'll be fine.
Regards the readiness monitors, I'm guessing there's nothing to diagnose. You don't have a MIL that's on, and you have no DTCs. Just those two monitors that have not set yet. My truck was that way for the first 8-9000 miles. I asked the dealer about it and they were clueless. I looked all over the web, and there's not a lot of info out there. The bits of info I could find says that at least two "de-soots" are required. My regens are pretty few and far between. My rationale was since there's no MIL and no codes, and I don't need an emissions test for several years, don't sweat it. Eventually the last two reset and the MIL quit flashing before starting. But it took a long time and a lot of miles. I have posed the question to Ramcares through another forum to see if I can get a definitive response on the drive cycle requirements to reset the monitors. I'll keep you posted.

 

[AH64ID]

@PRS great info on the flashing MIL.

As far as taking two regens to reset the monitors that should happen within ~48hrs run time, assuming 13+. The longest the truck will go between regens is 24 hours from the completion of the last regen. Most driving/operating situations allow the full 24 hours.

With my average speed of 33.8 mph I would do 9 regens in 8000 miles.

 

[Almost 13ranch]

Thank you for the responses. It’s now making me wonder if I should switch fuel suppliers to see if there’s any difference. I thought I was feeling a different throttle response and switched to a different station. I went back to the old station this last fillup. I’m at 9,400’ elevation and I’m sure that I need treated fuel. They both told me that they’re treating the fuel for cold weather.
How can you tell when the truck is doing a regen?

 

[SnoKing]

I’m at 9,400’ elevation and I’m sure that I need treated fuel.

Wow! Put an oxygen mask of that truck!!!! Where do you live?

 

[Almost 13ranch]

Wow! Put an oxygen mask of that truck!!!! Where do you live?

In mountains in south central Colorado.

 

[PRS]

Lucky guy. We're in Arvada with all the people.
You said you changed the batteries 3 months ago. Unless you kept one connected while you changed the other one, that would explain why it wasn't flashing when you first got it in August, and is flashing now. Disconnecting the batteries clears all the codes and starts the monitors over again.
I have attached a drive cycle I found on a website called smogtips.com. It's obviously not official and I have some questions about some of the procedure, but it may give some idea about what we're up against.