Hey Guys,

My check engine light came on about a week ago.
Scan showed trouble code P21DD.
"Diesel Reductant Tank Heater Circuit 1 signal low" was the translation.
Did some research, and looks like it was a somewhat common issue on some LML D-Max trucks.
Mine has 82K miles on it now, but saw on several forums where owners received letters from GM which extended the warranty coverage on this issue to 10 years/120K miles under Powertrain, (normally 5 years/100K for D-Max).
I bought it used in March, never got any letter from GM. Dropped it at the dealer this morning, the guy said their diagnostic fee is $159 (!), and if I pay for the repair, that fee goes away.
I asked the service writer about warranty, and he said warranty is only 50K miles for emissions. I said it is still under powertrain warranty, but he said that DEF system is strictly emissions, not PT.

I just got a call back, guy said my truck is ready, they replaced the DEF tank, reservoir, heater, and topped it off. I never gave them authorization to proceed with any work, so I am guessing either they did cover the repair, or we are in for a fight... (Looks like most dealers charge around $1100 for for this, on non-warranty jobs).
Anyone got any takes on this from experience or inside knowledge? Bets?
Will update when I get home with my truck!

GM has a special coverage on them. You should be covered.

Call GM customer service and complain. I'm not sure about the coverage. I left the dealer I worked at in 2016 (one of the best moves I've ever made) Also, it only needed the reservoir, it didn't need the other stuff.

NFC you were correct. Service writer was not aware of it, but the tech who does these jobs said he knew about it.
Strange thing is the remote start function stopped working a few days before the CEL indicator came on. I rarely use it, so didn't give it much thought. I guess maybe some malfunctions disable that feature, because it worked this morning. (Nice to have in sub-freezing temps like we got - Way too early to be below 30* in North Texas).
Dealer loaned me a brand new Colorado pickup, and they washed, vacuumed my truck, and reset all the tire pressures for this colder weather.
All was done at no cost, glad to see the dealer and/or GM backing their stuff.

I can tell you this. when i worked for Buick, we were well aware of the TSB's that were active.Company policy/guidelines. Hope he wasn't trying to pull a fast one and get it as non warranty and or customer pay. I have been looking for this specific TBS. Saw a lot with heater and tank replacement. That was it. Maybe it was a CYA and replace it all. People had complaints back then, it was a call to the zone office and SH*** hit the fan... Well at least this time they put customer satisfaction first.
Maybe he was hoping you had a tuner, Etc on it. That would kill the warranty and go into customer pay.Just an assumption is all I'm saying.

Case in point. I had a call 2 months ago on an ISX that was still in warranty. He put on the Complete delete. SCR/EGR ETC delete. Broke down on the shoulder. I couldn't get the proper data. He had cam/injector issues. He was out in left field for warranty.. SOL....

My experience with the remote start is that any time there is an existing code showing, it will not remote start.
Glad this worked out for you.

quote:

Originally posted by FootbrakeJim:
NFC you were correct. Service writer was not aware of it, but the tech who does these jobs said he knew about it.
Strange thing is the remote start function stopped working a few days before the CEL indicator came on. I rarely use it, so didn't give it much thought. I guess maybe some malfunctions disable that feature, because it worked this morning. (Nice to have in sub-freezing temps like we got - Way too early to be below 30* in North Texas).
Dealer loaned me a brand new Colorado pickup, and they washed, vacuumed my truck, and reset all the tire pressures for this colder weather.
All was done at no cost, glad to see the dealer and/or GM backing their stuff.

Wow, that is great to hear!

Seems like most automobile manufacturers care less about customer satisfaction once you purchase something. Glad to see GM doing the right thing!

I did five DEF heaters last week. Sad part is they have used the same tank and heater set-up from 2011 to 2016 . So far on the 2017 up L5P engine i have not ran into this issue yet.

Funny/curious thought regarding the service report I was given. It included the tech's comments. During the diagnostic testing, he reported the DEF Heater having an internal short, because it failed to draw sufficient Amps to meet specs. Not an electrical engineer, but wouldn't the basic principles of electricity say that a short circuit would draw MORE current, not less?

An electrical heating element is a resistive coil of wire inside a holder or housing. Generally they fail OPEN, not shorted. If it has 2 wires an ohmeter across the 2 should show a reading that would indicate if it was good assuming you knew what that should be or had a new one to compare it to. If it has only one wire, it’s got to be completing a circuit to ground and an ohm reading across those 2 points would be how you test it. If it was dead shorted on the input side to ground it would blow the circuit fuse. I just replaced a glow plug on my Duramax and it is just a heating coil inside the body. 1 wire and the body completes the circuit. Reads open with an ohmeter and does not heat up when connected across a battery. 2nd time I changed this one....#8 and a Bosch brand this time. Very easy to replace....Duramax.

It is very common for people to say something is shorted instead of saying it was an open, or the resistance was far higher than it should have been.

I used to have an employee that called a short circuit a short cut. Made me laugh, but I knew what she meant.

You would think a tech would call it by the correct terminology, but I guess you never know.

I work for a non-GM dealer...
1) if we didn’t charge a diagnostic fee, our entire day would be spent diagnosing peoples cars so they could bring them somewhere else to fix!
2) the service advisors are usually up on the TSB’s or extended service campaigns but there are hundreds and it’s impossible to be up on every one.
3) it might appear to be the same setup on all the trucks, but it’s very likely that if it’s a known issue then the replacement part may appear the same but is probably an updated or revised design.
4)don’t pay much attention to the techs notes - warranty repair orders get submitted to the manufacturer for payment and the techs and warranty administrators know exactly how to word it so that GM will pay the claim because they will bounce it if it’s not written up properly.

quote:

1) if we didn’t charge a diagnostic fee, our entire day would be spent diagnosing peoples cars so they could bring them somewhere else to fix!2) the service advisors are usually up on the TSB’s or extended service campaigns but there are hundreds and it’s impossible to be up on every one. 3) it might appear to be the same setup on all the trucks, but it’s very likely that if it’s a known issue then the replacement part may appear the same but is probably an updated or revised design. 4)don’t pay much attention to the techs notes - warranty repair orders get submitted to the manufacturer for payment and the techs and warranty administrators know exactly how to word it so that GM will pay the claim because they will bounce it if it’s not written up properly.

You are correct on the wording to get paid.
The DEF tank heater should be between 2-4 ohms and draw around 6 amps. Most of them will set the code when they are around 2.5 to 3 amps.

quote:

Originally posted by BD104X:
I work for a non-GM dealer...
1) if we didn’t charge a diagnostic fee, our entire day would be spent diagnosing peoples cars so they could bring them somewhere else to fix!.................................................................................................................

I no longer work at a dealer. I still do automotive work, but no longer for the public, but I've got something to say about diagnostic charges.
Most technicians/mechanics get some kind of flat rate or commission pay. (they get paid for whatever is billed out) I'm not a fan of working for free. If the diagnostic fee is $xxx, then it needs to be $xxx. Waiving the diagnostic fee "if you get it fixed here" is a load of crap. Time was spent do diagnose the problem, the technician needs to be paid for this time. If you go to the Doctor with a hurt arm you're going to pay for the x-ray regardless of whether it's put in a cast or not.

My point wasn’t about wether or not the techs deserve to get paid for their time or if it’s fair for the tech if a dealership waives it - most of the time people get very huffy about it and it’s usually because the service advisor does a lousy job of explaining it!

Diagnostic fee that's nothing. Most do it to cover the overhead. Hows this one.. In my line of work, some shops charge what they call..
"Call out Fee" to answer the phone after 6PM
Some get $50-$75.. You me to tell me you charging the customer this to answer the d a m n phone?. One of the many questions that are asked when they call. Do you charge a call out fee?
HE** no. I'm happy to get the work.

Good / Interesting discussion on the diagnostic fees, and the importance of correct billing/write-up terminology, guys.
Back when I was a shop mechanic, (40 years ago), I was paid flat rate.
I will admit my initial "sticker shock" at the dealer diagnostic fee, was because I incorrectly assumed that did not include all of the proper testing routine. I figured that was their charge to plug in a code scanner, and I would pay for the additional testing on top of that. Knowing what labor rates are these days, (and how much overhead costs can be), and that not all vehicle circuits are readily accessible for testing, the charge does not seam as unrealistic as I first thought it was.
TD3550, that "call out fee" is definitely something that would get my blood pressure up in a hurry!

The analogy is. Your calling me for Emergency Road Service on your Semi after i close the shop. Sure we are a 24/7 deal. this is the call out fee. The guy down the road has about 5 big wreckers with one service truck. Call out fee is $65.00. His theory is, i'm not getting out of the bed at 2AM for nothing. He said, you don't charge a call out fee. I told him, "What are you crazy"? He** NO.

I had a guy call the other day wanting me tell him what was wrong with his truck over the phone. He told me what all he has replaced ( around 700.00 in parts ) but still not fixed . I told him to bring it in and he said the labor rate was to high. Maybe he could have saved some money but who cares.