I have a 99 Silverado and the passenger side seat back will not lock back into the upright position. Locks fine into reclining positions. What could be the problem?

Ok first you will have to take out that lever and remove the plastic cover to see if a. The pin on the seat broke -b.if the latch that locks the seat has broken -c. If the spring on it broke

If it's binding the circuit breaker will shut off the recline motor. You have to replace the entire back frame to replace the motor

The gears for the recliner has been misaligned/broken. Disassemble and look for broken parts. Refer to service manual to realign,

It's a power seat or manual?

You must remove the motor, move the seat to the desired position and then reinstall the motor to lock the seat in the position.

Would you say it stays on about 30 seconds and does the passenger side do the same thing? If possible retrieving the codes will narrow down the search for a correct solution.If the passenger side is ok we may be able to eliminate the passenger side as bring part of the problem.Please advise so will know which way to go with your solution.


Condition/Concern: Driver and passenger heated seats inoperative or shut off in 30 seconds. There will be DTCs B2435, B2440, B3606 and/or B1825 set in the Drivers Seat Module. The adjustable pedal position sensor, seat recliner position sensor and both heat seat thermistors share the same 5 volt reference internal to the Drivers Seat Module. A fault in any of these components/circuits can make the heated seats inoperative or shut off in 30 seconds, as well as, the seat recliner and/or adjustment pedals may move in short increments when operated. A fault in heated seats, adjustable pedal or seat recliner will affect BOTH heated seats.
Note:: Even if the vehicle is not equipped with adjustable pedals DTC B3606 still may set.


To help isolate the area of concern use the Tech 2 or a comparable scanner and go to "Sensor Data" in the Drivers Seat Module. Monitor the following parameters for being out of range:
Recline Position- Normal range .39V-4.58V
Pedal Position (if equipped) - Normal range .39V-4.58V
Psgr. Seat Heat Sensor- Normal range 1V-4V
Drvr. Seat Heat Sensor- Normal range 1V-4V
If a parameter is found to be out of range inspect circuits for any opens, shorts to ground, or voltage. If none found replace the suspect component.

Please be aware of the following common areas of concern:

1. The adjustable pedal position sensor internally shorted pulling the 5 volt reference low. Disconnect the adjustable pedal position sensor and see if the heated seats start working correctly, if so replace. Note Important:: The APP (Accelerator Pedal Position) sensor is NOT the adjustable pedal position sensor. Make sure the correct sensor, adjustable pedal position sensor, is disconnected.
   
2. The seat recliner position sensor internally shorted pulling the 5 volt reference low. Disconnect the recliner position sensor and see if heated seats start working correctly, if so replace.
3. An open in either heated seat thermistor circuits (signal or low reference). The most common is the passenger thermistor where it passes through seat connector C305 pin "L" or "K" or C399 pins "R" or "G".
4. A chaff to ground on either heated seat thermistor signal circuits. The most common is circuit 5475 black/red or dark blue shorted to ground in the passenger seat near the buckle. Note Important:: The heated seat thermistors act differently to "OPENS and SHORTS" than the adjustable pedal position sensor and seat recliner position sensor. The adjustable pedals and seat recliner sensors can be disconnected for testing of the heated seats. Where as the heated seat thermistor circuit must be working correctly before EITHER heated seat will operate. Disconnecting one thermistor, which may have a concern will not allow the opposite heated seat to work correctly, BOTH side must be operational before EITHER heated seat will operate.
   

Clearing DTCs
If DTCs will not clear when using the Tech 2 or comaparable scanner after a repair has been made, try operating the device in which the repair was made. Example, if a repair was made to the passenger heated seat thermistor circuit, the DTCs may not clear unless the passenger heated seat is operated.
Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.

look for a strap that may have tucked itself in. or maybe a lever on the side?

On W-Body vehicles, the front seats are secured to the floorpan by two front hook attachments and two rear bolts installed to nuts welded to the floorpan.
The manually operated two-way front adjusters provides only fore and aft movement of the seat. When the seat adjuster handle located on the front seat is pulled up, the seat adjusters unlock, permitting travel of the seat. When the seat is in the desired position and the seat adjuster handle is released, the seat locks in place.
A power operated six-way seat adjuster is available. The adjusters are activated by three 12 volt, reversible, permanent magnet motors with a built-in circuit breaker. The motors are energized by a switch bolted on the seat side panel.
The three motors drive the front seat and rear vertical actuators and a horizontal actuator. When the adjusters reach the limit of travel, torque is absorbed through the rubber mounted grommets located between the motor and the support. An overload relay is provided in the circuit and will open should excessive stall be applied.
The optional 60/40 split bench front seats have seat back head restraints on the driver's and passenger's seat back. The head restraints are designed so they cannot be removed from the seat back without first inserting a small rounded tool inside the head restraint support tube to release the locking tab. The 60/40 split bench seat is equipped with a reclining mechanism on both the driver's and passenger's side. The recliner lever is located on the outboard side of the spring cushion. When the lever is pulled upward, the spring loaded dual linear reclining unit located in the cushion frame is released, allowing the seat back to be pushed rearward or allowing the spring loaded reclining unit to bring the seat back forward.
Bucket seats are equipped with manual reclining mechanisms. An optional six-way power seat adjuster is available. Some bucket seats are equipped with inertia seat back locks. This system allows the seat back to fold forward without requiring the occupant to release a locking lever or access to the rear seat area. During a sudden stop or deceleration, or if the front of the vehicle is nose down, the inertia system of the seat back lock will engage, holding the seat back in its rest position. A release lever is provided to allow manual release of the seat back lock when the vehicle is in the nose down position. The release lever is located at the lower rear outboard corner of the seat back.
Some W-Body vehicles (notably Pontiac coupes) have passenger front seats equipped with an E-Z Entry device. This is actuated, in an unoccupied seat, by completely folding the seat back forward disengaging the adjuster, and sliding the front seat forward to gain access to the rear seat area. To return the seat to its normal position, return the seat back to its rest position, and slide the entire seat rearward, engaging the adjuster.
W-Body rear seats are available in several styles including a rear seat with an integral child restraint device.

would need car in front of me and my oil can in my hand to clean the mechanism of accumlated dirt around the springs and the whatever and a nice drop of real oil and not that fish oil od wd40

check the adjusting bar on the pass. door side of seat.