KevinC506

I have a 2000 Sport 4L V6 automatic. I have been having a recurring issue with the two codes; P0121 TPS Throttle Position Sensor/Switch A Circuit Range/Performance Problem and P0740 Torque Converter Clutch System Malfunction.

This is the third time these codes showed up together. What happens is the RPMs at first shoot up at initial engine start up and die down. Today that hasn't happened (this ordeal started 1 day ago) and idle RPMs are sitting a little lower than usual. About 150-300 lower. The transmission doesn't shift properly. I get up to 3000 RPMs going 25mph then it will eventually shift. Does that around 45 too. Best way to describe it is that it likes to shift whenever it feels like it and always at a lot higher RPM.

Like I said this is the third time the same thing has happened. The last time this happened was about two weeks ago. I ended up changing Tranny fluid/filter and spark plugs (they were toast) as well as oil/filter. The issue went away and everything seemed to run even better than before.

The first time was about a month ago, but it was only reading as the TPS code giving me problems. Replaced the TPS sensor and worked fine.

Now that it is back again doing the same crap as before I can't seem to figure out why and where to look. As you can tell it likes to subside for awhile and then come back. What gives? Tranny fluid is full. The only thing I can think of is a short somewhere or TCC Solenoid? I also have hood vents and I'm thinking that it may have something to do with it all considering this stuff started happening not too long after I put them in. Moisture getting in there maybe?

I don't know what else it could be. Any ideas?

Radi

Where did you get the TPS? Aftermarket? If so you might try a new one. (yeah, I know...but the aftermarket electronics aren't exactly China's best product)

KevinC506

Got it at advanced auto parts.

Bruce in Montana

It probably would'nt hurt to adjust the throttle valve cable as well....just to rule it out. It's quick and easy.

CCKen

Here's some diagnostics data for P0121:

P0121-TPS VOLTAGE DOES NOT AGREE WITH MAP

POSSIBLE CAUSES

HIGH RESISTANCE IN 5 VOLT SUPPLY CIRCUIT
HIGH RESISTANCE TO GROUND IN 5 VOLT SUPPLY CIRCUIT
INTERMITTENT CONDITION
HIGH RESISTANCE IN 5 VOLT SUPPLY CIRCUIT
HIGH RESISTANCE TO GROUND IN 5 VOLT SUPPLY CIRCUIT
MAP SENSOR
HIGH RESISTANCE IN MAP SENSOR SIGNAL CIRCUIT
HIGH RESISTANCE TO GROUND IN MAP SENSOR SIGNAL CIRCUIT
HIGH RESISTANCE IN SENSOR GROUND CIRCUIT
PCM
THROTTLE POSITION SENSOR
HIGH RESISTANCE IN THROTTLE POSITION SENSOR SIGNAL CIRCUIT
HIGH RESISTANCE TO GROUND IN THROTTLE POSITION SENSOR SIGNAL CIRCUIT
HIGH RESISTANCE IN SENSOR GROUND CIRCUIT
PCM

Perhaps you should first try removing and cleaning the MAP Sensor and TPS connectors with electrinic cleaner then reinstall them, clear the codes and see if they reappear. If so, perform electrical checks of the MAP and TPS systems. There's instructions on how to test the TPS circuit on the forum. Do a search for it. Most of the high resistance possibilities above would require checking the wiring between the MAP and TPS and the PCM. The 2K/2K1 diagnostics instructions involve the use of the DRB III tool (dealer).

TEST ACTION APPLICABILITY

KevinC506

Ok I'll take a look at it after work. Although a few weeks ago I did take apart the then entire throttle body and clean everything head to toe and the MAP sensor. TPS I just cleaned off the connectors. I'll give it another go and see if anything changes.

Just read the TPS test write up. Seems like the related symptoms are exactly what I am having. I'll get the volt meter handy.

CCKen

Check the reference voltage going to the MAP sensor while you're at it. The connector configuration is the same as the TPS (pin wise) and the reference voltage is the same.

This is form the FSM (Modified by me):

Back probe the connector.

(1) Test MAP sensor output voltage at MAP sensor connector between terminals 3 and 2. With ignition switch ON (RUN) and engine OFF, output voltage should be 4-to-5 volts. The voltage should drop to 1.5-to-2.1 volts with engine running and at a hot, neutral idle speed condition.

(2) Test MAP sensor supply voltage at sensor connector between terminals 3 and 1 with ignition ON. The voltage should be approximately 5 volts (+/-.5V).

Pin 3=Orange
Pin 2=Dark Green/Red tracer
Pin 1=Brown/Yellow tracer

CCKen

What did you use to clean the TB and the sensors?

KevinC506

Last time I used Valvoline Carb and Throttle Body cleaner. Today I used Lynnx east penn cleaner on all of the connectors.

The voltage is good on the TPS. cleaned out the connectors and still fruitless.

Never got a chance to see your post about the MAP sensor voltage so I'll do that tomorrow. Didn't get to in depth looking at the wiring harness but I'll look at it again. From what I saw didn't look too corroded or anything.

nicks_98xj

im haveing this same problem but mine is throwing like 3 codes for the trans and one for the tps and every time i put it in reverse it spudders and some times stalls then it dosent shift right when i drive but if i shut it off and restart it most of the time it will start shifting normal again its annoying

KevinC506

Got another diagnostic today after cleaning out the map and tps because it started working again but light didn't go off.

P1492 Ambient Temp sensor high, P0122 TPS does not agree with MAP, P0740 TCC, P0122 (i think its actually 123, typo:/) TPS voltage low. Which I checked the voltage yesterday to and from the TPS pins on the connector and the readings were 5.0v, .99v, and .00v (ground) which is all normal or at least close to it. So no idea why that one popped.

What is the ambient temp sensor? don't know where that's located.

When I got back home the light went off as I thought it would. Takes a little bit of course. The idle, however, is still a little bit lower than normal but working fine and not sputtering like it used to.

So I know I can't just ignore those codes even though everything returned to normal tonight. Tomorrow morning we'll see what happens. Bet it messes up again.

Radi

Ambient temp sensor is under the battery.

If you are getting a P0122 and the TPS is operating normally, then it's possible the MAP is not. One reading is compared to the other- ie: engine load as measured by the MAP should make sense when compared to throttle angle reported by the TPS.

Will be interesting to see what you get tomorrow.

klaw13

I was hoping after reading this thread it would end with a solution. Guess I was wrong, what fixed it?

KevinC506

Ok after laughing at my post and own ignorance from a few years ago. I mean V6??? Really? Go me. Anyways, yeah turned out to be rain dripping on the TPS and shorting it (had hood vents). Liquid electrical tape coating over the connector fixed it from ever happening again.

klaw13

Thanks Kevin, I also have hood vents and just went through a drive through car wash.