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Is This Okay?

Dennis1947
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Dennis1947 Enthusiast

Dennis1947

Posted
Posted

Just purchased a Silverado 1500 RST Z71 with the 5.3 engine.

To avoid any future issues created by the use of DFM, when it looks like the DFM may begin to activate due to road conditions I have switched into manual mode and L10 on the transmission. I have not noticed any issues.

Am I safe in continuing this practice?

By the way, this is my first Silverado, having moved from a 22 GMC Canyon.

davester Senior Enthusiast

davester

Posted
Posted

No.  Your truck will eventually notice the pattern, and then regularly send electrical shocks through the steering wheel to you, until you stop doing it.

  • Haha 1
Dennis1947 Enthusiast

Dennis1947

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17 hours ago, davester said:

No.  Your truck will eventually notice the pattern, and then regularly send electrical shocks through the steering wheel to you, until you stop doing it.

Sounds fun.

KARNUT Senior Enthusiast

KARNUT

Posted
Posted

You use to be able to drop a gear to lock it out. People used to do that until they were on the interstate. Some never would up shift. I used a tuner. 

newdude Senior Enthusiast

newdude

Posted
Posted (edited)
On 5/17/2026 at 9:04 PM, Dennis1947 said:

Just purchased a Silverado 1500 RST Z71 with the 5.3 engine.

To avoid any future issues created by the use of DFM, when it looks like the DFM may begin to activate due to road conditions I have switched into manual mode and L10 on the transmission. I have not noticed any issues.

Am I safe in continuing this practice?

By the way, this is my first Silverado, having moved from a 22 GMC Canyon.

 

 

L9 to turn off DFM.  

 

DFM stays active in L10.  

Edited by newdude
newdude Senior Enthusiast

newdude

Posted
Posted
10 hours ago, TrueBlue said:

I've not heard that L10 would prevent DFM from kicking in. Does it?

 

 

L9 does, not L10.  

taze Enthusiast

taze

Posted
Posted

It also seems like to me it won't kick in over 80, is that true? Maybe because it needs too much throttle to stay up there?

 

 

newdude Senior Enthusiast

newdude

Posted
Posted (edited)
21 hours ago, taze said:

It also seems like to me it won't kick in over 80, is that true? Maybe because it needs too much throttle to stay up there?

 

 

 

 

Any speed above 8mph it can be active if all of the other operational parameters are met.  I bolded some key ones below on the enabled and inhibited reasons from the description and operation of DFM.  

 

The conditions listed below determine when cylinder deactivation is enabled.

  • Engine coolant temperature is between 40−126°C (100−264°F)
  • Engine has been running for greater than 20 s
  • Engine oil pressure is between 187−585 kPa (27−84 psi)
  • Engine oil temperature is between 20−128°C (68−262°F)
  • Engine speed is between 700 and 2675 rpm
  • Ignition voltage is greater than 11 V
  • Transmission is not in, neutral, park, first, second, or reverse gear
  • Vehicle is not in heater performance mode
  • Vehicle is not in tip in bump acceleration mode
  • Vehicle is not in oil aeration mode
  • Vehicle is not in low gear ranges
  • Vehicle speed is greater than 13 kph (8 mph)

 

The conditions listed below may be reasons for inhibiting deactivation:

  • Accelerator pedal out of range or rate of pedal application too fast
  • Catalytic converter over temperature protection is active
  • Cylinder deactivation solenoid driver circuit faults
  • Decel fuel cutoff is active
  • Enabling criteria not met
  • Engine oil pressure and temperature out of range
  • Engine speed out of range
  • Maximum cylinder deactivation time exceeded
  • Piston protection is active, knock detected
  • Reduced engine power is active
  • Torque management is active
  • Transmission gear incorrect or shift in progress
  • Vehicle speed out of range
Edited by newdude
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  • 2 weeks later...
GMCustomerService Senior Enthusiast

GMCustomerService

Posted
Posted

We are glad to know you haven't noticed any concerns so far with your engine, however our team suggests taking this inquiry to your preferred Chevrolet dealership for their advice. Your peace of mind is important to us, and we want to provide a layer of assistance in working towards full confidence in your Silverado. Please fill out our support form here https://s.chevy.com/support-request with more details so our team can further assist you. 

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