Owned this Silverado Crew Cab since new, quite reliable until 2022, AC Delco Trans Module melted July 2022, local GM dealer had last GM one on shelf.
History:
- DEF tank replaced under emissions warranty in 2018.
- Filled DEF tank July 2022 and substantially still full today.
- Oct 2022 code P20B9 Reductant Heater A Control Circuit OPEN, kept driving it and code went away, returned twice in November, went away.
- Ordered tank heater kit and on shelf Dec 2022.
- Jan 2 2023 tank heater code returned and would not self correct. Replaced heater, cleared code and speed reduction self cleared after short drive. Tank 100% full, still.
- Jan 15 2023 speed reduction message returned, DIC message reads "Exhaust Fluid Quality Poor", no codes.
- Bought new Blue Driver scanner, a nice glovebox code clearer but not much more.
- Bought new XTOOL D8BT Wireless Diagnostic Scan Tool, had it 2 weeks and while useful to watch Live Data, trigger Regen, Fluid Quality Tests its reset functions may not duplicate a Tech2, eg) toggling all 3 DEF heaters on and off. Looking for better scan alternatives. Tool will display ECU version numbers, no reset capabilities.
Repairs and Tests:
- Replaced both Nox1 and Nox2 sensors with new GM parts, original sensors sticking, mostly Nox1. Rapid deceleration throttle off tests now both go to 0% NOX.
- Replaced DEF pump with new. Pressure 500 kpa / 74 psi
- Removed DEF injector, minor cleaning with solvent cloth, Quantity test 50 ml in 2 min, 3 distinct rapid pulse fine sprays.
- Performed static and driven DPF regens, temps rise to 650C at EGT 2, tests pass. NOX 2 readings follow Nox 1 up and down. Soot now 8 to 15.
- Reset every Reductant System function with scan tool multiple times including DEF heater procedures. No certainty XTool D8BT resets actually accomplish anything.
Failures:
- Unable to pass either Reductant Fluid Quality Test or Reductant System Warning Test. Tests time out with message "Interrupted" Speed Reduction is now at Level 5.
- Monitoring Reductant System Data during tests shows:
1. Reductant Injection Inhibit Reason usually starts with scan messages" Nox Cat Temp" until engine temp warm, "DPF Regen" next on occasion, then "None" and ends with "Interrupted"
2. Reductant Pump command will read 15-24%, pressure steady at 500 kpa
3. Reduction Injector Command will read only short bursts of 1 second every 60 seconds of 10% to 100%.. Have watched this Command driving and occasionally it will issue 2 or 3 one second bursts in succession, then nothing for another minute. And on this goes until yesterday.
General Motors selling dealer, Wednesday, Feb 22, 2023:
- Passenger side airbag recall was now in stock and delivered Silverado for that repair only. Discussed possibly re-flashing ECM with service desk, yes they do it, about an hour to perform. Left dealer after airbag swap.
- Monitoring Reductant data driving away noticed that the Reductant Injection Inhibit Reason now displaying "DTC Set' after warm up and no data from either the DEF pump nor the DEF injector. Did the dealer tech install this "DTC Set" or did swapping out the airbag serial numbers do the deed? Either way our diagnosis is crippled for now.
Asking for suggestions of next move, wise or otherwise.
Bernie b
History:
- DEF tank replaced under emissions warranty in 2018.
- Filled DEF tank July 2022 and substantially still full today.
- Oct 2022 code P20B9 Reductant Heater A Control Circuit OPEN, kept driving it and code went away, returned twice in November, went away.
- Ordered tank heater kit and on shelf Dec 2022.
- Jan 2 2023 tank heater code returned and would not self correct. Replaced heater, cleared code and speed reduction self cleared after short drive. Tank 100% full, still.
- Jan 15 2023 speed reduction message returned, DIC message reads "Exhaust Fluid Quality Poor", no codes.
- Bought new Blue Driver scanner, a nice glovebox code clearer but not much more.
- Bought new XTOOL D8BT Wireless Diagnostic Scan Tool, had it 2 weeks and while useful to watch Live Data, trigger Regen, Fluid Quality Tests its reset functions may not duplicate a Tech2, eg) toggling all 3 DEF heaters on and off. Looking for better scan alternatives. Tool will display ECU version numbers, no reset capabilities.
Repairs and Tests:
- Replaced both Nox1 and Nox2 sensors with new GM parts, original sensors sticking, mostly Nox1. Rapid deceleration throttle off tests now both go to 0% NOX.
- Replaced DEF pump with new. Pressure 500 kpa / 74 psi
- Removed DEF injector, minor cleaning with solvent cloth, Quantity test 50 ml in 2 min, 3 distinct rapid pulse fine sprays.
- Performed static and driven DPF regens, temps rise to 650C at EGT 2, tests pass. NOX 2 readings follow Nox 1 up and down. Soot now 8 to 15.
- Reset every Reductant System function with scan tool multiple times including DEF heater procedures. No certainty XTool D8BT resets actually accomplish anything.
Failures:
- Unable to pass either Reductant Fluid Quality Test or Reductant System Warning Test. Tests time out with message "Interrupted" Speed Reduction is now at Level 5.
- Monitoring Reductant System Data during tests shows:
1. Reductant Injection Inhibit Reason usually starts with scan messages" Nox Cat Temp" until engine temp warm, "DPF Regen" next on occasion, then "None" and ends with "Interrupted"
2. Reductant Pump command will read 15-24%, pressure steady at 500 kpa
3. Reduction Injector Command will read only short bursts of 1 second every 60 seconds of 10% to 100%.. Have watched this Command driving and occasionally it will issue 2 or 3 one second bursts in succession, then nothing for another minute. And on this goes until yesterday.
General Motors selling dealer, Wednesday, Feb 22, 2023:
- Passenger side airbag recall was now in stock and delivered Silverado for that repair only. Discussed possibly re-flashing ECM with service desk, yes they do it, about an hour to perform. Left dealer after airbag swap.
- Monitoring Reductant data driving away noticed that the Reductant Injection Inhibit Reason now displaying "DTC Set' after warm up and no data from either the DEF pump nor the DEF injector. Did the dealer tech install this "DTC Set" or did swapping out the airbag serial numbers do the deed? Either way our diagnosis is crippled for now.
Asking for suggestions of next move, wise or otherwise.
Bernie b
