The electric seats will not adjust forward or backward. The up and down and recline works good though.

use a meter and test the switch and motor

All cars are different it might just me a stripped gear or something but yeah you should be able to replace it yourself. Youll probally have to take the seat out though :/

which maxi fuse gets hot ? # fuse , plus amps The power seats uses a 30 amp circuit breaker ,not a fuse . The horn gets power from the same circuit breaker . . Sounds like something is drawing to much current. Do you know how to use a amp meter to test current flow . Disconnect componets till draw goes away ? How to use a wiring diagram to pin point areas in a circuit to test ?
Is there corrosion on the pins where the seat circuit breaker plugs into ? Reach under your seats an see if one of the seat motors is hot .
DeVille
The left and the right power seat system consist of the following components:
• The seat switches
• The seat relay modules
• The 4 reversible motors:
- The front vertical motor
- The rear vertical motor
- The horizontal motor
- The recline motor
These 4 motors operate independently of each other.
When the entire seat switch is pushed to the FORWARD position, the forward input of the of the seat relay is grounded.
The seat relay module supplies battery positive voltage (B+) with a ground to the horizontal motor, in response to this input. In order to drive the seat forward, the motor runs until the switch is released.
The BACK position works similar to the FORWARD position with the exception that the voltage polarity supplied by the seat relay module is reversed causing the motor to run in the opposite direction. This action drives the seat backward.
These recline switches operate similar but independently:

The seat relay module could be bad , If you don't know how to do automotive electrical circuit testing it mite be a good idea for you to take your vehicle to a qualified repair shop.
Could have diagnostic trouble codes stored as well .
DTC B0846 +5 Volt Reference Out of Range
DTC B0856 Battery 2 Out of Range
DTC B1656 EEPROM Write Error
DTC B1658 EEPROM Checksum Error
DTC B1982 Source/Battery Voltage High
DTC B1983 Source/Battery Voltage Low
DTC B2101 Recline Aft Switch Failed (Eldorado)
DTC B2101 Recline Aft Switch Failed (DeVille)
DTC B2102 Recline Forward Switch Failed (Eldorado)
DTC B2102 Recline Forward Switch Failed (DeVille)
DTC B2103 Rear Vertical Down Switch Failed (Eldorado)
DTC B2103 Rear Vertical Down Switch Failed (DeVille)
DTC B2104 Rear Vertical Up Switch Failed (Eldorado)
DTC B2104 Rear Vertical Up Switch Failed (DeVille)
DTC B2105 Horizontal Aft Switch Failed (Eldorado)
DTC B2105 Horizontal Aft Switch Failed (DeVille)
DTC B2106 Horizontal Forward Switch Failed (Eldorado)
DTC B2106 Horizontal Forward Switch Failed (DeVille)
DTC B2107 Front Vertical Down Switch Failed (Eldorado)
DTC B2107 Front Vertical Down Switch Failed (DeVille)
DTC B2108 Front Vertical Up Switch Failed (Eldorado)
DTC B2108 Front Vertical Up Switch Failed (DeVille)
DTC B2109 Lumbar Aft Switch Failed
DTC B2110 Lumbar Forward Switch Failed
DTC B2111 Lumbar Down Switch Failed
DTC B2112 Lumbar Up Switch Failed
DTC B2115 Recline Sensor Failed
DTC B2116 Rear Vertical Sensor Failed
DTC B2117 Horizontal Sensor Failed
DTC B2118 Front Vertical Sensor Failed
DTC B2119 Lumbar Forward/Aft Sensor Failed
DTC B2120 Lumbar Up/Down Sensor Failed
DTC 2130 Seat Motor Failure

If the seat is not moving forward or backward, but you do hear a click or a motorsound- chances are that you dropped in some change or other debris may be blockling the way. You might also have blown a fuse - look for fuse no. 30, which is a 30 Amp fuse.
Once you've checked all that and if the motor still does not run, then the problem may be with your wiring.
Wire colors between the switch panel and motor are:
• Fore/aft-Tan and Lt Green
• Front up/down-Dark Green and Dark Blue
• Rear up/down-Yellow and Light Blue
• Recline up/down motor's Blue and Light Green

You need to check for power at the motor when you try to activate the switch. If there's power then you have a drive cable issue. If this is a manual seat then the problem is the actuator assembly itself,the cable,mechanism,etc. Remove the seat & take a good look at it. You'll see a problem,write back.

The control switch has developed a problem (intermittent contact or just broke inside) Replace the switch. That should fix it.

You can move the drivers seat back by turning on the power, getting in the seat and position your feet firmly on the fron flor with your back firmly against he seatback, and then engage the switch pushing back - while pushing like hell with your feet. You can actually hear the seat drive shaft turning while the seat moves back. The principle should be the same for moving forward, but pressure would have to be aplide to the back of the seat.

usually not. seat is electric and adjusts to extent allowed by that. Passenger seat has a back release on it though.

I'm assuming this is a power seat. If so, there are separate motors that control the various functions of the seat such as forward/backard, recline, lumbar support, etc. It could be that the motor or an electrical connection to the motor for the forward/backward motion is faulty. Normally all of the motors would be on the same power circuit, so if some of the functions are working then it is probably not a blown fuse.

Just one other personal observation, I have actually seen an instance where some loose pocket change had spilled under the seat and a quarter had become wedged in the track that the seat slides in and had jammed the tracks so tightly that the seat would not move.

One thing to note is whether or not you hear anything when you try to move the seat forward/backward. If you hear a click or a buzz when you press the button then that could mean that something is physically jamming the seat tracks. If you don't hear anything when you press the button, then that more than likely means a problem with the motor or the electrical connection to the motor.

MY POWER SEATS WILL GO UP & DOWN AND WILL TILT FORWARD & BACKWARDS BUT WILL NOT GO FORWARD OR BACKWARDS. IT JUST MAKES A HUMMING SOUND WHEN TRYING TO GO FORWARD OR BACKWARD. IS THE POWER SEAT SYSTEM A GEAR SYSTEM, OR HYDRAULIC SYSTEM?