According to the Hyundai VIN decoder, it is a 4 speed automatic, 2WD.
https://www.vindecoderz.com/EN/check...SC13D34U851997

I may get those sensors by the end of the week. Not driving the vehicle until these are changed out. Will give update. I hope it is not the shift solenoids.

 

The latest update is not good. I replaced the transmission input and output sensors. Basically no change except a camshaft position sensor code P0340 popped up and I thought I saw a code for the crankshaft position sensor P0335 but was too quick to erase the codes. I went ahead and replaced the camshaft position sensor, especially since the connector was pretty trashed from heat damage. As soon as I got 4 miles down the road the tranny started slipping and burning and RPM jumping. When I got the car back, I got a camshaft position sensor and another throttle position sensor code.
My theory is back to 'something is killing the 5 volt reference very intermittently'. Since the car has to be driven for a few miles before these codes show up, I expect the ECU is going bad and the 5 volt source is slowly dying.

This is so very frustrating. I am not going to spend the money on an ECU and I can't keep throwing money at it with no results. I wonder if I can get $300 to $400 for in its current condition? It is a Florida car so there is no rust or corrosion, but the paint on the hood/top has faded and lost its shine. I sure hate to be beat by this intermittent/flakey condition... and even if I did change the ECU, there is no guarantee it will even fix the problem. As I understand it, you can't even just swap out the ECU with a salvage part.

 

You may be causing yourself some unnecessary problems , expense and work.
Before changing any parts, you should confirm the part is malfunctioning or eliminate as many possibilities as you can.

What I would do if I suspected the 5 volt reference voltage is dropping or going out would be to connect a voltmeter to the circuit and see if that is what is actually happening.
Keep in mind if that is happening , it affects all the other components that share that voltage and should throw several codes.That does not seem to be the case.

Replacing a PCM on later year vehicles can require a scan tool to do a "Parameter Reset" or you may not even get the vehicle to start with the replaced PCM and to add to the problem ,when you reinstall the original PCM the system gets confused and now will not start with the original PCM either.

Remember I asked , how do you know the TPS signal is actually getting to the PCM all the time That needs to be confirmed.

 

I think I mentioned that I had a voltmeter hooked up to the 5 volt source for a couple of days and it was solid. Also , I moved the voltmeter to the signal side and operated the throttle cable and saw a very smooth voltage change from about 1/2 volt to about 4-1/2 volts with the key in run. Attempting to to that with the engine running will over speed the engine once you get to a certain point. Whatever is happening only occurs after the vehicle has been driven for a few miles. If I had a pin-out of the ECU, I might be able to connect to the output wire for the TPS source and return, but finding service information with that detail is nearly impossible on the web without a subscription. 2 codes for 2 sensors, both which have been replaced, and both that use 5 volt reference really suggests that the reference voltage is dropping out when this is acting up. Dropping out may not be the correct term. It could be that it is just very intermittently loosing the voltage which may not throw a code for the other sensors. It could be a wire shorting to ground and possibly at high enough resistance to not knock the 5 volts out. Loss of 5 volts totally would shut the engine off I believe...... and why do you supposed that a momentary disconnection of the battery gets me down the road further?

 

The momentary problem with the TPS signal could be the problem the PCM detects and throws the system into Limp mode. Disconnecting the battery allows for a reset and the problem is eradicated until the next time it takes place.
A wiring diagram is required to tell you where the signal to the PCM from the TPS is going. The check has to be done at the PCM because if there is a connection/wiring problem in between that is the way you confirm it.
Sometimes it can be something like a loose fit to the pins in the plug, maybe corrosion. Don't know without looking and checking.

 

Do you or any one else know if the wheel (ABS) sensors use 5 volts? I'm thinking that is an area subject to moisture or corrosion because of location.

 

You seem to be missing the point and that is the code the system is directing you to.
The 5 volt reference may be getting to the TPS, but the PCM is telling you via the code it is not seeing a continuous response.

Wheel speed sensor systems do send down a bias voltage to run a check on system integrity before you even move the vehicle. If there was a problem in that system it will usually throw a code so as to provide some direction troubleshooting.

I may be wrong, but I gather you are not sure just how to go about following through on the troubleshooting and therefore suggest you consider having someone with the required info available and tools to locate and correct the problem. The rule is ,"Test Don't Guess".

 

I understand that, but without wiring diagrams and connector pin outs, there is only so much I can do. I proved that the TPS is good through my testing but, as you know, the ECM is pretty inaccessible being behind the lower dash in the center of the vehicle. Earlier I was seeing flakey 5 volts that I though was a meter or back probe problem. I have not been able to recreate that unstable 5 volt situation. Before pulling the ECM out for inspection, I am trying to find any sensor with a 5 volt reference that might be chaffing to ground in a high resistance situation (not enough to throw a code). I'm only going down that path because of the recent Camshaft sensor code (which I also replaced but still throws a code). It is apparent to me that the sensors are probably not failing but the 5 volt reference is.... either threw a high resistance short or a bad ECU power supply output.

I won't use a dealer tech to try to figure this out, as billable hours would exceed the value of the vehicle.

BTW, I'm not guessing... I'm trying to use logical troubleshooting with what I have to work with. I use to be be able to run down electrical issues all the time back in the day when you could get a Chilton's or Haynes manual that had wiring diagrams in them. Today's version of those manuals are worthless. A set of factory manuals for this vehicle are several hundred dollars.... and accessibility behind the bulkhead is extremely difficult.

 

Mr. JB,
There are several sensors that share that 5 volt reference voltage. The nice part is the computer has already provided the system/circuit that is having a problem.
If,,,,,,,,,,,,,,,,it was the 5 volt itself it would affect all the sensors on the line/circuit and you could get codes for all of them.

I realize it is a stinker to chase down the wiring to the PCM and maybe someone has a diagram to help here. I have many times had to physically chase down a wire by color , the hard way when a diagram is not available and the $$ for a one time use seemed excessive, but there are only 3 choices , either give the job to the place that has access to the diagram or do it the hard way or get the pin out somehow.
As far as any kind of electrical to work on vehicles these days, there isn't too much that is easy anymore . Checking a TPS with a voltmeter or ohmmeter is not that reliable , what is required is a scope to see the waveform and if there are any problems. That is one reason many shops even have a scope , but they are not that experienced with using it.
Sometimes Autozone will provide a wiring diagram on there website after you insert all the info. I have never used them, but maybe it might help you.

 

Not holding my breath, but found a troubleshooting chart that says the one of the most common causes for a camshaft position sensor code (PO340) is a bad crankshaft position sensor. That doesn't make sense to me, but this morning I located the sensor under the starter, got the starter and shield off and immediately noticed a cracked wire covering leading to the sensor and a lot of greasy black oil in the vicinity (probably slight valve cover seep). Everything is very tight and I didn't initially think I could get the starter off which is needed for access to the sensor and to clean up the area. So as I was working the sensor out of the hole, the entire wire covering came off and I could see indications of wire strands in the insulation of the sensor wires. If there was ever an opportunity for a high resistance fault, this would be it. Let me see if I can post some pictures. A new crank position sensor should arrive tomorrow. The first picture shows the sensor harness lead with the cracked covering still on the vehicle. Wish me luck.