# Gen 2 Diesel Def level stuck on empty?



## 6speedTi (May 18, 2018)

First thing is use a good scanner. A good scanner will access pending codes and history. See what you have as a starting point.

The pump unit is all in one. I 
have issues as well. Level indication jumps around at different levels and throws a CEL. Same code all the time. DEF level quantity fault. The only fault for now but the DEF system is functional. I plan on dropping the DEF pump unit and washing it with warm water to see if that helps. Did some online research. This particular DEF pump unit is used in multiple applications upto 2018. It is naturally flawed by design. You can replace it with a new one only to have the same issue again in short time. They cost about $400 plus installation. This is a expensive unit that is flawed from the drawing board. You can try to pull the cover off to get to the module and short harness. Remove the connectors and use electrical contact cleaner then apply dielectric constant grease. Next you can try to replace the module. It's right there when you access the harness and pump. Small square black box. Next would be the pump assembly. The module is much cheaper in price but from what I have been reading it has a low failure rate. The pump unit has the highest failure rate. 
GM has a troubleshooting table for this.
Check connections first.
Next use a meter to check resistance and voltage values. Then repair or replace as per troubleshooting findings.
I know GM doesnt waste time ringing out wires so they probably check the connections then replace the pump assembly which is the most common fix. Then they might start chasing the wires. So that's my take on what I've learned so far. I can't wait to drop my pump unit and see what it looks like. Hopefully a good warm and soap cleaning will work. I'm thinking that it has solid crystal build up over time like you see when you spill DEF on the ground or on your car.


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## ChevyCruizer (Dec 31, 2021)

Great thank you. I do have a module ordered… just for what you said …cost. My plan was to pull the pump and clean it up. Appreciate all the info. I will let you all know how this weekend pans out


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## 6speedTi (May 18, 2018)

Don't forget to replace the seal for the pump assembly. It may be ok to reuse but you never know. The locking ring removal and installation tool will make it easier. Fuel Tank Lock Ring Tool OEM 6599 https://a.co/d/cZFhCpK


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## ChevyCruizer (Dec 31, 2021)

Thank you I picked up a seal at a local Chevy Dealer. They didn’t have the lock ring tool so that came off old school. I did mark with a paint pen location if anything could have gone better I coulda had catch pan closer to tank. When lock ring let go Def was definitely coming in a hurry.
Cleaned up harness and connections with contact cleaner. Definitely corrosion on 2 pins on the module larger connector coming directly from pump. Applied some grease to all connections


I gave the pump a good warm soapy water bath in a new bucket and Dawn dish soap. Had a basting brush and a couple toothbrushes and gave it a good scrubbing after it soaked for a while. Changed water out a couple time and repeated and then rinsed and blew it off with an air hose a few times. 
Re assembled everything with new pump seal. Lock ring back on and hooked up harnesses.
Put in about 2 gallons of Def in ( no leaks) and let it set while I rotated tires. 
Started car and my “27 Miles to 65 mph max” warning was gone. DIC now says 323 miles till empty and Def level now 20%. So progress was made. Ran and got another jug of DEF and added most of it. DEF now says OK. Decided to give it a test and drove to see my daughter in St Louis yesterday afternoon/evening. No issues. 200 mile round trip. So calling it a win for now. 

shout out to @6speedTi for the info and guidance. Much appreciated!!!


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## 6speedTi (May 18, 2018)

Glad to hear. I'm next. In at 33% level.
When it gets down to warning level I'll drop the pump assembly and clean it.
Hopefully I'll have similar results.
Here is the lock ring tool. Cheap enough. 








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## 6speedTi (May 18, 2018)

ChevyCruizer said:


> Thank you I picked up a seal at a local Chevy Dealer. They didn’t have the lock ring tool so that came off old school. I did mark with a paint pen location if anything could have gone better I coulda had catch pan closer to tank. When lock ring let go Def was definitely coming in a hurry.
> Cleaned up harness and connections with contact cleaner. Definitely corrosion on 2 pins on the module larger connector coming directly from pump. Applied some grease to all connections
> 
> 
> ...


Did you replace the module? I recall you said you purchased one. Curious if the cleaning of the pump assembly or cleaning the connectors solved the problem.


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## 6speedTi (May 18, 2018)

Yesterday I finally removed the DEF pump assembly. My DEF fluid warning was at the mileage countdown to the 65 mph warning. My scanner showed 9% fluid quantity even though the display said it was empty and refill now. The pump was clean and no signs of build up. The level float was clean and moved freely. Reinstalled the pump and added about 2 gallons of DEF. My scanner read about what was in the tank. The display still had the countdown to 65 mph. So I filled the tank to full. The highest percentage on my scanner was 89%. The display still reads the same empty to countdown message. So my scanner says 89% when it should be 100% and the display is still stuck on empty with mileage countdown to 65 mph. So they both disagree and both are not accurate. I disconnected the battery and hoped for a reset of the system. That didn't help. Drove several miles and still the same situation but less miles on the countdown. So now it's worse than before. I decided to replace the pump since they have a high failure rate. Pump is on order. $500 tax and shipping included from a GM seller on Ebay. Cheapest I've found. This should hopefully solve my problem until it fails again in about three years or so. 
If your wondering why not change the module instead? Even though the module is cheaper ($170) it has a very low failure rate. I also cleaned the connectors and added dielectric constant grease to all connectors. 
Ok that's the short version. 😄


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## ChevyCruizer (Dec 31, 2021)

Thanks for the update. So far so good on my cleaning. I’ve filled Def 2 times since cleaning and no additional issues. I didn’t not ever replace the module. I figured it’s worth the try the cleaning the pump and connectors first before I opened the module and could not return it. I’d be interested to hear if pump fixes it. I’m sure I’m going to need one sooner or later.


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## 6speedTi (May 18, 2018)

I'm still not fully convinced the pump is at fault. Unfortunately the cheaper more common sense approach is the pump. Dealership will charge an enormous fee in diagnostic and parts plus labor. It could cost me over $1,000 when I sign the bottom line. I did come across a similar problem during a online search where a software reset corrected the problem. I did not have the details so just guessing. Update as soon as the next is completed. Pump arrives Saturday.


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## 6speedTi (May 18, 2018)

So I did some research while waiting for my new def pump to arrive. Looks like a reset needs to be done on the pump to calibrate the level quantity. This is per the maintenance manual. So I purchased a OBDlinkmx+ from Amazon same day delivery. Added the Gretio app. Have to purchase additional support specifically for both Gen 1 and Gen 2 Cruze diesel. From the reviews it handles additional functions for the diesels and more. Hopefully it will reset my def pump after installation. Many reviews on diesels look like it's a life saver to avoid a trip to the dealership. 
🤞


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## 6speedTi (May 18, 2018)

New pump is in. Works good. The level quantity is not fluctuating anymore and no CEL. The issue I have is the level quantity showing on my scanner versus known quantity in the tank are a mismatch. Tank full reads about 67%.
I did a quanty level reset but it still reads 67% after the reset. I believe the reset was too be done with the tank empty so the system knows where the empty reference point is. My guess but I'm sticking with that idea. It does count down as I'm driving and when it reaches the same point it jumps back up to 67%. Did this twice so I'm thinking it is self adjusting until actual level and indicated level agree. Time will tell. In the meantime all is good and no fault.


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