Hello All, I need a fresh pair of eyes and another brain. 2004 Saturn Vue, 2.2l, manual transmission, car was tooling along on the interstate, all of a sudden, felt like I was running out of gas. A few hesitations but still running. Within 2 miles i was off the highway and she died and wouldn't stay running. Would run horribly if I gave it gas, but would stall. Towed home, scanner read P0068. I changed out the MAP sensor, as the car has 171,000 miles on it and all sensors were original knew it wasn't an impossibility. Then trying to start it, same condition but now P0122,P0123,P0223. I have checked for shorts, bad wiring, revisited all grounds, cleaned and secure. Couldn't find a wiring diagram at the time so I replaced the pedal sensor and the TPS. To know avail. I ran through every item I could find on the web for possible symptoms and was left with the PCM. So, I got a refurbished, flashed, downloaded with my vin number, PCM from Flagship One, reprogrammed the key. Started her up...same codes. Any ideas? It ran fine then this. Thanks for thinking about it.

 

All the information I can find on your vehicle shows that the TPS (and IAC motor) is integrated into the throttle body. So did you replace the throttle body? Did you do the idle relearn procedure? I haven't found any specific directions for your vehicle, but for most GM vehicles it's a sequence of idling for 3 minutes, 1 minute off, then idling three minutes again.

 

Some of those codes are related to the sensor at the pedal while other codes listed are related to the actual throttle position sensor on the throttle body.

It seems a bizarre that both the sensor at the pedal and the sensor built into the throttle body would go bad at the exact same moment.

I suspect it is a wiring issue. The PCM swap had no effect which rules out the PCM.

Both the pedal sensor and TPS sensor signal probably are routed through the same harness once they get in front of the firewall.

For these codes to trigger, the voltages have to be out of range of what is expected. In order for the voltages to be truly directly comparable to each other meaning to be able to compare them to each other, I'm willing to bet they share a common ground. And that ground is probably no longer grounded due to a break in the wire. Likely under the hood but could also be where it goes through the firewall. Vibration and chafing never lead to anything good.

The code that triggers when the voltage is above the possible voltage of 5 volts is the one that to me implies the voltage is all over the place and at one point seemed to spike above 5 volts because there is no ground and therefore the relative voltage drop can't really be determined by the PCM.

Had you performed any activities under the hood in the days or weeks prior to this occurring? You may be dealing with an accidentally pinched ground wire from previous work or from something you took off to check. It happens to the best of us.

To check the ground theory, find the ground at each sensor and measure resistance it to frame ground. Should be zero.

This assumes that one end of each sensor is actually grounded. You'd have to look at the PCM diagram to see if the reference wire for each sensor is grounded at the PCM and/or grounded elsewhere. For that engine I personally have no idea.

Again to be able to compare them, I'm thinking there is a common wire against which both voltage measurements are made so that the reference is exactly the same for the two measurements. A break in this non-grounded wire would have the same effect as losing a ground in the circuit.


Check your work around the MAF sensor. Could be a wire in common with the TPS and the pedal sensor.

Please let us know what you find

 

If the VUE is grounded like my L, grounds run to several ground splices. These are basically 1/4” female connectors on each wire plugged onto a ground tab that is bolted to the body. My car had 6-8 on each tab, they really are just pushed together and covered with a plastic cover. I removed the cover and cleaned the connections and my fans, horn and front lights all started to work correctly. Floating grounds are a pain to locate, a factory service manual is invaluable.

 

Clear all of the codes with the scanner and start over. Rescan for codes and work from there. You shotgunning parts at it hasn't helped you at all. Sorry if I sound critical, but the process of elimination is the way to go. Check codes, check what the codes indicate and proceed to the next one. You may have replaced one defective sensor with a bad one out of the box and not even know it. Did you keep the old sensors? If so, put them all back in and start over.

 

thanks for all the replies. I hate shotgunning parts as well, but at the time I could not find a wiring harness diagram for this vehicle. All the other 2.2l ecotecs use a 3 wire connector to the tps. Mine has an 8 wire connector. Finally found one after the fact. Both sensors have the 5 volt reference voltage when the key is on. Can't measure that reference when i try to run the engine causes it's running so poorly it shakes the whole car and then dies.. I'll try the grounds again. I have found three. All cleaned and reattached. Maybe there is another. I replaced the ECU as a last ditch cause I can't find any thing. Maybe there is a short to ground but the engine won't stay running long enough to do tests and nothing shows with the key in the On position. I'll check the resistance as well. It failed so quickly, you would think it would be something like a broken wire, not just a bad connection.

 

Checking the grounds at the grounding points is indeed a helpful check, but if the continuity is not there, then the circuit is not grounded.

Since the sensors should be live with the key on, you should be able to slowly adjust how far the pedal is pushed and watch the voltage on the wire that goes back to the PCM to see if It is changing appropriately through its range. I suspect neither of them are. This is why the car will not run properly. It has no idea how far the gas panel is depressed and no idea what angle the throttle plate is at, So it doesn't know how much gas it should be giving through the injectors.

Go back on Google and write down exactly what situation triggers setting of the codes. Then you know exactly what situation is setting them as well as what the normal response should be. If something is open circuit, you should be able to find it. Not necessarily easily, but you should be able to find it. For both halves of the throttle control system to go out at the same exact time is illogical.

Maybe one signal goes into a module and is compared with the other signal. I have no clue.

But my point is that one being not connected properly could actually be influencing the behavior of the other. When you put the two malfunctioning items together, you generate a third messed up state which drives both signals out of range and sets all of those codes.

If you have the wiring diagram, please attach it to a post and I will try to analyze where things might be going wrong. No promises

 

derf, 2005-2007 Ions use the 8-pin throttle body (w/TPS and IAC integrated), as OP has indicated he has on his Vue. I'm attaching the wiring diagrams of the 2005-2007 2.2L Ion Engine Performance Circuit, which should be very much like the Vue, except possibly for wire colors. Pedal position sensor is at the bottom of page 1, throttle body is at the top of page 3.


Page 1

Page 2

Page 3

 

Thank you sir.

 

So I have checked the 3 grounds I could find, 2 on the engine, one at the ECU/PCM. All were still clean and tight from 2 years ago when I cleaned them. I got .03 Ohms resistance at each one. I attribute that to the wire itself. I took readings at the pedal sensor and TPS and I am going to include a chart with those. I read in another post on this site that the sensors don't have any specific parameters to fall in, just that the voltage changes per pedal and throttle movement. I could not find anything online to dispute that. Thanks for the wiring diagram Oldmarine. I did find one specific to my car, the only difference between the two is the wiring color. The colors on the one you provided are totally different than mine (don't get me started on the genius of that). And as you can see, neither of the sensors share a common wire. They both go directly to the ECU/PCM. So at this point, I am thinking all I have left is to painstakingly separate the wiring harness and look for some damage. Nothing is apparent; no cuts, wear points, rubbing, damage, etc. to be seen now. I agree that none of this makes sense and is illogical. But, there has to be a reason. Once again, I'm open to any ideas, cause I can't lose any more hair over this as I'm already bald.