I recently changed my transmission and since that has happened, I am having trouble starting my vehicle. I had some codes come up that stated that the crankposition sensor and MAF or VAF is having trouble. But I had changed the crank positon sensor because I thought that had something to do with it not starting. It would crank up sometimes after about 10 or 20 minutes of trying it, and it would run for a while then quickly die out, but I dont want to burn out my starter doing this. So I want to know what it could be that could possibly be causing this?

The OD fuse may have opened or it could be speed sensor failure. The OD off state also could be an indication of transmission trouble.

What make , model and year vehicle ? Don't know how much you know about the modern automobile , how computes and how data transfer happens ! Speedometer , tachometer , fuel gauge , tempreature gauge etc.... Sensor inputs from these sensors are iinputs to the PCM - engine computer and to get to the gauge in the instrument cluster , this info is sent by a message on the serial data bus . The VSS - vehicle speed sensor not only supply's info the speedometer but also the PCM use's for transmission shift points .
How often does this happen (RPM and speedometer drop out ?) Could have lose connector in the wiring harness or at the PCM . A wire that is grounding on on the frame or body .The first place to start would be checking for DTC'S diagnostic trouble code's . Could make diagnostic's a whole lot easier !

If the engine light is blinking you have major issues with the vehicle. Have scanned at autozone or similar for codes this will give you a idea what is wrong. Then get back to me when you have codes

You describe a drivability issue which should turn on the Check Engine Light. Find an OBDII scanned and scan the ECU (Engine Control Unit) for any powertrain control trouble codes, then get back to me with those codes. We can take it from there.

By the way, which Hyundai vehicle is this?? Accent?.. Which year?

check trans fluid, if ok....have the vehicle scanned for trouble codes at autozone. this may be an electrical issue.

Do you have codes with that engine light?
Do you have a digital odometer?
Insert the Key into the Ignition and
Turn from OFF to ON (not Start) ON is just before Start.
Do this 3-times: OFF to ON (not start), OFF to ON (not start), and OFF to ON (not to start).
Leave the Key in the ON (not start) Position.
Look at the Digital Odometer.
With the Egine Light on there will be Codes in the Odometer Display.
Record these Codes and get these Codes back to me.
These codes should pinpoint the Problem.

What is the Transmission Fluid Level and Condition?
Remember to Check the Transmission Fluid with the Engine On and at Normal operating temperature. Check it with the vehicle in Park or in Neutral (WITH the Parking Brake engaged).
When was your Transmission Fluid and Filter Changed?
After 35,000 miles they should be changed. Do not get the Superflush, as this does not change out the filter. Use the correct, recommended Transmission Fluid, do not buy the cheap stuff.

The "brain" they are talking about is the Transmission Solenoid. It looks like a box, and is usually found on the front of the Transmission Because of it's location the electrical connections are prone to corrosion and oxidation (white stuff) on the electrical connectors, causing problems with shifting. You can remove the electrical connections from ALL the connectors on the vehicle; Check and Clean then and re-plug them back in, and check operations.
The Transmission also has Sensors. These are easily located on the Transmission. They send electronic information to the computers and are used during shifting. As stated earlier: remove the electrical connections for each sensor, and clean both sides of the connections.
One or more of these Sensors may be malfunctioning, causing the shifting problems. You may also easily remove these Sensors and clean the inside end of the sensor (they gather small metal particles on them), reinstall, replug and check operations.
Let me know if this helped, or if you have additional information or questions. Feel free to contact me at FixYa.com!

have vehicle scanned some auto stores such as auto zone/advanced auto scan for free check ur area the trouble code will give u a place to start also state had trouble code before could be returning

If the transmission OD (overdrive) light is on or flashing, it means the transmission controller has diagnosed an internal transmission fault. To diagnose the problem, a scan tool that can read transmission codes must be plugged into the vehicle diagnostic connector (usually located under the dash near the steering column). The scan tool will then display the transmission code(s) that turned the warning light on. What happens next depends on the code. If the code indicates an internal performance problem, the transmission will probably need the attention of a specialist. But if the code indicates an electrical fault, a bad sensor or solenoid, you may be able to fix the problem without having to take your vehicle to a transmission shop. Hope this helps.

Have the vehicle scanned for diagnostic trouble codes to see if any have set due to a malfunction.Either a scan tool,or a code reader can access your vehicle's computers.If there is a diagnostic trouble code present,places like All Data online have the diagnostic routes for each trouble code.The diagnostic route,performed properly,will lead to the conclusion of what is malfunctioning.

More than likely something was disturbed accidentally,a connector to a sensor,a sensor itself,possibly even a vacuum line,although a vacuum leak will usually result in a high idle,but an engine that wants to stall,so visually check all these items.At this point,i would do the visual checks,and also scan the vehicle for any possible trouble codes,as a trouble code will point in the direction of the problem.Places like Auto Zone will pull the codes for free.