Is This Okay?

Dennis1947 · May 18

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 · May 18

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.

Dennis1947 · May 18

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.

TrueBlue · May 19

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

KARNUT · May 19

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 · May 19

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 May 19 by newdude

newdude · May 19

10 hours ago, TrueBlue said:

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

L9 does, not L10.

taze · May 19

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 · May 19

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 May 20 by newdude

GMCustomerService · June 1

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.