* If it has an overdrive "off" button (usually on the shifter or console): The button itself is your indicator. Lit up (usually an "OD OFF" light) means overdrive is off; unlit means it's on.
* If it doesn't have an overdrive "off" button: There's no light or indicator. Overdrive will be engaged automatically unless the transmission is in a lower gear. You'd have to rely on the tachometer to see if the engine is revving higher than normal at a given speed (indicating overdrive is off because the engine is working harder). This method isn't foolproof, though.
To be certain:
1. Check your owner's manual: This is the definitive guide for your specific truck's features. Look for the section on the transmission or instrument cluster.
2. Look at the shifter: Some shifters have positions explicitly showing "OD OFF" or a similar indicator.
3. Observe the tachometer: As mentioned above, higher RPMs at a given speed might suggest overdrive is off, but this is not a reliable method.
In short, the lack of a clear indicator on the 2004 F-150 XL highlights the importance of consulting your owner's manual. Without an overdrive "off" button, there's no visual cue beyond inferring it from the engine's behavior.
