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Replaced DEF tank still having problems.

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24K views 12 replies 8 participants last post by  Allpacio  
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#1 ·
2020 2500hd 6.6 originally had the melted harness and melted heater so I replaced the tank which comes with a harness. Had service DEF system and derate again. Dropped tank and found DEF tank harness had pin 12 incorrectly switched with wire. Ordered correct harness for new tank and now have new codes P208A for reductant pump control and P20B9 for heater control 1 back again. Ordered reductant pump module thinking I fried it from getting the wrong harness with the tank previously. Programmed module. Still have P20B9 and P208A and DEF system warning. Has anyone gone through this. Pretty lost at this point. I am going to have to go through the diagnostics all over again. Is there a certain reductant pump or heater fuse? Appreciate any help ahead of time. Thank you-Tony.
 
Discussion starter · #7 ·
Ottowood said:
Model years 2020 through early build 2022 were originally built with cavities 6, 12 and 13 unoccupied. After mid-year 2022 (herein known as late build), the pump/sender assembly and the corresponding connector terminals were moved. Terminal 10 was moved to cavity 12 and terminal 11 was moved to cavity 6. All tanks built after that date, including tanks to service the 2020 – early build 2022 are configured this way. If it is necessary to replace the reductant tank in an early build vehicle, it will come with the correct harness already installed and installation would proceed with no special instructions.
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originally installed the tank with harness it came with but heater 1 and 3 wouldnt come on when turning on heaters with active command. So DEF message came back on dash and check engine light on. So now installed another tank with correct harness. So should I be using the modified harness and maybe the module is shot from the heater burned. Lost at this point. I wish GM would just give you the right parts or issue a recall at this point.
 
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