Seems transmission gear shift problem

This is from Repair Pal...just Google your code (P0758) to find other helpful suggestions

OBD-II Code P0758 is defined as a Shift Solenoid B Electrical The purpose of the automatic transmission is to match the engine's optimum power and torque characteristics to the driver's desired rate of acceleration and speed by auto-selecting different gear ratios or 'speeds' to power the wheels. Shift solenoid B enables the transmission to shift from 2nd gear to 3rd gear. It does this by re-directing the flow of the transmission fluid which changes the position of the shift valves in the valve body.
When the code P0758 is set in the Powertrain Computer, it means that the Powertrain Computer or PCM is not seeing the specified rpm change that occurs during a shift from 2nd gear to 3rd gear. It's also not seeing the correct increase in road speed from the vehicle speed sensor.

P0758 Symptoms

• Check Engine Light will illuminate
• Vehicle will not shift from 2nd gear to 3rd gear properly
• Decrease in fuel economy
• In unusual cases, there are no adverse conditions noticed by the driver
• In some cases, there may be performance problems and possibly misfire-like symptoms

Common Problems That Trigger the P0758 Code

• Defective Shift Solenoid
• Defective Shift Solenoid wiring or connector
• Defective Valve Body
• Dirty transmission fluid that restricts the hydraulic passages

possible cause is the torque converter clutch servo/solenoid
changing on the indicator but no drive through the gear box
run the fault codes and check for problem clutch servo/ solenoid or transmission control module
check all wiring and connections to transmission

Gear shifts happen depending on how far the gas pedal is
pressed & the load on the vehicle

Transmission pressures change as you drive under different conditions,so the shifts happen at different speeds

There is no passing gear

If you have a 4 speed,you have 3 forward gears & an overdrive
forward gear, plus torque converter lock-up

You saying you have no 4th to 3rd downshift or whatever

Maybe the transaxle is failing mechanically inside-worn out

If your car is manual, clutch not releasing completely, loose or damaged shift linkage, insufficient transmission oil or oil is in poor condition, sticking or jamming gears, worn or damaged striking rod. Autozone, Advanced Auto, or O'reilly can scan/read your check engine code. Speedo faulty or vss speed sensor no longer works.

P0700 is a informative transmission code, about some problem there; the P0733 and P0734 is the specific problem there.
I would first try changing the fluid and filter. Although the fluid may look like it is brand new, with 100K on the fluid, I can assure you that even if those miles were all highway at steady speed and no load that the fluid has deteriorated and no longer lubricating the internal parts properly and that there is some debris in the ******.If codes return and shifting problems are still present, there is definite internal failure, possibly the pump or in the clutches.
DTC P0733The powertrain control module (PCM) uses the crankshaft position (CKP) sensor, input speed sensor (ISS) and output speed sensor (OSS) to determine engine speed, input shaft speed and output shaft speed. These sensor readings are used to determine the current gear ratio and RPM slip across the torque converter. The PCM uses this information from the sensors to determine if the commanded gear matches the actual gear. During normal driving conditions, the PCM will adapt main line pressure via the pressure control (PC) solenoid to prevent slipping and harsh shifts. Shift solenoid 3 is used to apply or release third gear clutch. The PCM controls 3rd gear by controlling the ground for shift solenoid 3. The PCM will turn the solenoid OFF, open the driver circuit, when 3rd gear is commanded On to apply 3rd clutch. Shift solenoid 3 is supplied ignition voltage from the fuel pump relay whenever the PCM commands the fuel pump relay ON. DTC P0733 sets when 3rd clutch still slips after the PCM has commanded high main line pressure.DTC Parameters
DTC P0733 will set if the PCM detects an incorrect actual 3rd gear ratio when 3rd gear is commanded On when:- The condition exists for longer than 3 seconds (2001)*- The condition exists for longer than 3 seconds, 1 minute is allowed to elapse, then condition exists again for longer than 3 seconds (2000)- The high main line pressure has been commanded- The transaxle is in a forward gear- The input speed is greater than 224 RPM- The vehicle speed is greater than 5 km/h (3 mph)- The speed noise parameter = NO- The steady state ratio fail counter equals 255 for an in-gear failure, or the shift fail counter is greater than 100 on a downshift or upshift to 3rd gear (128=0 or normal operation)DTC P0733 diagnostic runs continuously once the above conditions have been met.
DTC P0733 is a type A DTC for 2000, type B for 2001.**Applicable to vehicles built after June 2000.
Diagnostic AidsImportant: If DTCs P0745, P0746, P0756, P0758, P0761, P0763, P0766, P0768 or P0789 is set, diagnose that DTC first. A diagnosed PC solenoid, shift solenoid 2, 3 or 4 low/high circuit fault DTC may have caused DTC P0733 to set.Important: If a shift solenoid performance DTC P0783, 4th gear stuck ON, is set, diagnose that DTC first. A 4th gear stuck ON may cause no 3rd gear, no 2nd gear, or TCC stuck Off.
Refer to Pressure Ports - Air Check and Parts Description for pressure apply points and for component/location description.
Possible causes of no 3rd gear are listed in the flowchart on the succeeding page.
Verify TRANSMISSION ISS and TRANSMISSION OSS read correctly on Scan tool.
Make sure the pressure control, shift 2, shift 3 and shift 4 solenoids are not intermittently sticking. A sticking shift solenoid 4 may cause 4th gear to be applied from an initial start resulting in no 3rd gear. Audible sound should be similar for all solenoids. A muffled tone indicates the need for replacement.
Check this pinout HERE
P0734 refer at ratio 4 gear, and the rocedure is the same.
Hope helps.

Hi James, The gear changes on modern vehicles is often controlled by speed sensors mounted onto each wheel. The sensors also control the ABS, traction control and activate the speedo. Have a diagnostic scan carried out and determine if the sensors are all in working condition. Regards John

While some people will tell you to change or flush the transmission fluid and see if it gets better. I would like to warn you it probably won't help much on your car. The Hyundai's transmissions have a high failure rate and the fluid changes and repair in a bottle fixes won't change anything. Just check if the fluid level is correct and make sure that the wires that go to the transmission are on clean and tight with no burns or shorts. Remember the transmission shifts gears based on info from the TPS sensor and a speed sensor. So if the CEL was coming on and you didn't scan the computer, it might just be a bad sensor and not the transmission. Take it to a Hyundai dealer not a Transmission shop.

hi, try taking to down to your local garage and asking then to have a look.. it might need a new clutch though if its serious but the gears might just need oiling

Your going to have to get your car scaned for codes. Auto Zone can scan it for you for free and tell your what you'll need to fix it.
It sound's like your VSS Sensor (speed sensor) is not working and your ECM is not getting the signal from the transmission to know when to shift the gears.
Becareful not to burn out the transmission till you get it fixed. The sensor it self is not that expansive and to replace it is easy and takes about 30 min to do.
If you get a P0720 or a P0722 code, then it's your speed sensor. It's an esy fix and Auto Zone can give you instrction on how to change it. 
Good luck, it takes about 30 min to change and hope this helps.

did u check wiring at speed sensor,damaged wiring or defect speed sensor,if no signal from speed sensor tranny will not work properly!