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Discussion Starter · #1 ·
Yesterday as I prepared for my weekly 3.5 hour commute on Monday morning I checked the weather as it had taken a turn for the worse in the last day going from 40 degrees with rain to freezing rain changing to snow on saturady to single digits on Sunday with strong winds. The truck was pretty much ice covered from my trip on saturday and the forecast was for 0 to sub zero temps on sunday night. So I decided to put the radiator cover on and to plug the truck in for the night in preparation for my early morning departure. I had read some of the posts about about setting off the codes using the block heater if it wasn't cold enough, but since it was predicted to go below zero I plugged it into the timer and took the chance. The truck started right up in the morning with only a momentary flash of the glow plug indicator light and no check engine light. Tranny temp stayed real low throughout the trip and engine temps stayed below 220.


Everything was fine until after about 3 hours into my trip I stopped to get a cup of coffee. I only shut it off for 5 - 10 minutes, but after restarting the truck the check engine light came on. Since the dealer that I bought the truck from was only a short diversion from the trip to my office I stopped there first. I had them pull the codes and 4 codes came up.

1) Coolant Temp sensor
2) Fuel Temp sensor
3) Air intake Sensor
4) Transmission Module Sensor.

I wasn't too surprised by the first 2 and the 3rd. The fourth surprised me. The first 2 I can relate to the problem that others have mentioned due to the block heater though I am not sure why it came on only after I stopped. The thrid might be related to running with the radiator cover on and getting a hot sensor by parking the truck and not getting enough cool air. The fourth I don't understand, but since the light came on the truck does shift differently. The symptoms are that it revs higher before shifting. It does shift, but just revs higher before shifting.

The dealer gave me 2 options.
1) Leave the light on and make an appointment for them to check out.
2) Have them reset the light and see if it comes back.

I took option #1 and have an appointment on wednesday.

Today was probably in the low to mid 30's for a high and tonight may go to 18. Back home it is supposed to go to -10. I plugged the truck in tonight as I figure I can't set off any more codes than I already have and then I don't have to let it idle as long to warm up. :)

What are everyone else's experiences with the LBZ with the block heater and the engine cover, I only used the radiator cover and not the bottom cover. Anyone else setting off codes in a similiar situation?

Any comments on this please let me know. Thanks.
 

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I had the first 3 codes on my new LBZ due to use of the block heater + winter cover when the ambient temperature was around 20 degrees. I don't recall that the fourth code (transmission) showed up but the shift pattern was modified with late shifts before the code was cleared. It seems the newer engines are much less forgiving of using the heater and cover than my '01 LB7. On the other hand, I really like the power and feel of the LBZ. Shortly after Christmas I made a run upstate to pick up a very large old transmitter which was large enough I had to leave the tailgate down in my CCSB. Deciding to avoid the interstate, I took U.S. highways home keeping my speed around 62 and ended up with 21.8 mpg for the return trip. On the way upstate, at 72-75 on the interstate I averaged 18.2. Hopefully this will improve a little with further break-in and and summer diesel but it is still in line with my '01 which usually averaged 17.8-18.6 in my mixed highway/city driving.
Rodger
 

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I am having the same problem guys. Same codes. The dealer here is trying to blame it on my 20's. Which were on it when I bought it..
 

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This is an issue with the ECM software. The trans code is also related. Basically when you use the block heater and the front cover, the coolant and ambient temperatures at start-up don't agree with what the ECM thinks they should be and the TCM doesn't like what the ECM is tell it. As a result, you set a bunch of codes.

Supposedly they're working on a software fix. The problem is annoying but it's not damaging anything.
 

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Outside Temp Using LBZ Block Heater

Not haven taken delivery of "The Silver Fox" yet, what can you tell me about using the block heater? I had a block heater in our Ford PS and alway's plugged it in anytime we were going to use the truck and the outside temp was below 32 degrees. Is there an outdoor ambient temp restriction on the LBZ when using the block heater?


Truck on!!!
 

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There's no restrictions that I am aware of. I'd go ahead and use it. Like I said, there's only the annoyance factor. You're not going to damage anything when these codes are set. Just keep an eye out for when the software fix is released.
 

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The annoyance factor is fairly large for in-town driving because the upshift points are raised quite a bit after the codes are set. A couple of things I was told during my visit to the dealer (and I have not empirically tested this!)

1. If you don't use the winter front AND the block heater, you will not set the codes since the software is looking for a large drop in intake air temperature after starting which will happen when the winter front is not in place.

2. The code will reset after 3 starting cycles where the correct conditions are met to check the sensors. Apparently these must be actual cold starts after the vehicle has been off for 8 or more hours so cycling the ignition will not reset the codes.

I set these codes less than 2 weeks after I took delivery of the LBZ, had them reset and have not had a problem since. I have used the winter front some but have not used the block heater since I normally park in the garage plus Illinois is experiencing either an early spring or a mid-winter thaw.

Rodger
 

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Discussion Starter · #8 ·
Dealer Results

Took
 

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This is my first post since i don't know much about diesel motors-- but I do know about this heater engine code thing. I live in Ariz and do not even own
a radiator cover. but on a couple of nights when it was down into the 40's
I usesd the heater figuring it would be good for the mtr to start warm--bingo the engine lite came on--took the dealer two days to figure out to not use the block heater.
 

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Discussion Starter · #10 ·
Dealer Appointment Results

Took the truck to the dealer today. It took a couple of calls to get them to answer questions. It wasn't until after 4:00 pm that they even looked at the truck. Did not get the final answers about what they found until I got there to pick the truck up. I had thought that being a new sale from them and dropping the truck off at 7:30 AM when they had opened that it would have gotten more attention. In many ways I think that I knew more than they did.

End result: don't install the engine cover and run the block heater unless below 0 degrees. They reset the codes and sent me on my way.

By the way: on monday my windshield washer fluid pump stopped working with no indication of low fluid. After heat soaking all day it did work. Dealer confirmed system worked. I assume GM filled the system with fluid that could not tolerate the lower NE temperatures. (this is my first truck that entered service in winter time)

I also have a set of stock non-camper mirrors now in boxes as they replaced the stock mirrors with the 06 camper mirrors today. The right side seems distorted so I need to adjust the mirrors and see how they work in the day time. My eyes may be getting old, but has anyone else noted any distortion in the right hand mirror? Many seem to be complaining about the new mirrors versus the older style. The ones that I had on the 01 worked fine except I had limited vision around my 8 ft wide trailer and that they were totally manual. This may be a more appropriate discussion in the exterior section. I know that the moderator will adjust if needed.:)

Thanks for everyone input. Great forum for learning about Duramax. Thanks to all the people that contribute.
 

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Discussion Starter · #11 ·
Annoyance factor

Sorry if I didn't mention this before but I would have to agree that the annoyance factor is large due to the shifting point.

A real PIA around town.
 

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Have never used the heater, but have used upper cover several times up to 40*. Book says to use anytime below 32* I seem to remember. (but then i am getting old & tend to forget where i am). Anyway, no codes set!!
 
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