Gear Position light D4 is always flashing irrespective of gear.

Re-adjust the shift linkage to set the lever higher so it is in park when the indicator says it is. Until you do this adjustment on the linkage, the key will be locked in the cylinder. The shifter lever MUST be ALL the way up to park position in order to remove the key.

overdrive is the fourth gear.D1,D2,D3,D4 now drive truck at 80 kmh
cruise at steady speed no fuel pedal movement, downshift from D4 to D3 you should feel RPM raise .. after push brake pedal a little you should see RPM raise 300 to 400 rpm.
shift pattern is 1st gear ,second gear,3rd gear and lock up(torque converter clutch). 4th gear with lock up
hope it helps

The proper thing to do would be to hook up a factory or professional type scanner an check input data to the PCM from the Transmission internal mode switch . Error means the instrument cluster is loosing data from the PCM - engine computer .

The lever assembly-manual shaft detent with internal mode switch (IMS) is a sliding contact electrical switch assembly that corresponds to the PRNDL position selected. Each of the PRNDL positions has a unique ground pattern on four wires from the PCM.
The assembly consists of two major components:
• The internal mode switch that consists of:
- The housing (1), which makes up the stationary contacts.
- The insulator (2), which makes up the moving contacts and is secured on the detent lever (4).
• The lever assembly which consists of:
- The manual shaft (3)
- The detent lever (4)
The range detection is accomplished by securing the moving contacts to the detent lever. When the driver selects a PRNDL position, the detent lever inside the transmission rotates. This rotates the insulator which in turn grounds the four wires in a unique pattern for each gear selection, corresponding to the PRNDL position selected. The IMS is electrically connected by five wires (four of which the PCM supplies voltage to and one wire that is a common ground) to the transmission pass through connector.


Range Selector Displays Incorrect Range
The transmission internal mode switch (IMS) is a sliding contact switch attached to the selector detent inside the transmission side cover. The four inputs to the PCM indicate the position of the transmission range selector. The input voltage level at the PCM is high, B+, when the IMS is open and low when the switch is closed to ground. The four input parameters represented are Signals A, B, C and P, Parity. Refer to Transmission Internal Mode Switch Logic .
Install a scan tool.
Turn ON the ignition, with the engine OFF.
Select IMS on the scan tool.
Place the range selector in each transmission range: P, R, N, D4, D3, D2 and D1.
Does each range selected match the scan tool IMS display?
--
Go to Intermittent Conditions in Engine Controls - 3.4L
Go to Step 2
2
Select IMS A/B/C/P on the scan tool.
Place the range selector in each transmission range: P, R, N, D4, D3, D2 and D1.
Does the IMS A/B/C/P display the specified values for each range?

Your best bet , take your vehicle to a qualified repair shop.

Check tranny fluid--motor warm in park

Its for manually shifting an automatic transmission

It's probably a bad internal mode switch . The sensor is input to the PCM - engine computer .
The lever assembly-manual shaft detent with internal mode switch (IMS) is a sliding contact electrical switch assembly that corresponds to the PRNDL position selected. Each of the PRNDL positions has a unique ground pattern on four wires from the PCM.
The assembly consists of two major components:
• The internal mode switch that consists of:
- The housing (1), which makes up the stationary contacts.
- The insulator (2), which makes up the moving contacts and is secured on the detent lever (4).
• The lever assembly which consists of:
- The manual shaft (3)
- The detent lever (4)
The range detection is accomplished by securing the moving contacts to the detent lever. When the driver selects a PRNDL position, the detent lever inside the transmission rotates. This rotates the insulator which in turn grounds the four wires in a unique pattern for each gear selection, corresponding to the PRNDL position selected. The IMS is electrically connected by five wires (four of which the PCM supplies voltage to and one wire that is a common ground) to the transmission pass through connector.

Range Selector Displays Incorrect Range

The transmission internal mode switch (IMS) is a sliding contact switch attached to the selector detent inside the transmission side cover. The four inputs to the PCM indicate the position of the transmission range selector. The input voltage level at the PCM is high, B+, when the IMS is open and low when the switch is closed to ground. The four input parameters represented are Signals A, B, C and P, Parity. Refer to Transmission Internal Mode Switch Logic .
1
Install a scan tool.
Turn ON the ignition, with the engine OFF.
Select IMS on the scan tool.
Place the range selector in each transmission range: P, R, N, D4, D3, D2 and D1.
Does each range selected match the scan tool IMS display?
--
Go to Powertrain Control Module Replacement in Engine Controls - 3.1L or Intermittent Conditions in Engine Controls - 3.8L
Go to Step 2
2
Select IMS A/B/C/P on the scan tool.
Place the range selector in each transmission range: P, R, N, D4, D3, D2 and D1.
Does the IMS A/B/C/P display the specified values for each range?
HI/HI/HI/HI
Go to Step 12
Go to Step 3

Your best bet , take it to a qualified repair shop !

The d is for drive, the number is for what gear you are using.Driving in 3rd gear all of the time will decrease gas mileage, and increase engine wear, but as long as the engine rpms aren`t too high there is no immediate damage.

its AUTOMATIC you dont have to do a thing u realy need those lower gears for towing and heavy loads for hill not for normal day to day driving just leave it in D4 dont touch it

D4 is slipping and not engaging. This means you need a transmission. you're losing a gear

D4 - this gear means that all four automatic gears will be able to work (1,2,3,4)
D3 - Three gears will be able to work (1,2,3)
D2 - Two gears (1,2) - L2 means the same thing
D1 - One (low) gear (1)

For your car, drive it in d4. this means that all forward gears will work, including overdrive (4th gear). It will be fine to leave your car in this gear.