V1 Captain Dave's City Goblin #336 - 07 SS/SC Donor

[Rauq]

Documentation makes C201 look like a big connector ("I/P Harness to the Body Harness")- my first clue was that APP Sensor connector Pin F goes to B11 on the C201 connector. You do raise a good point, though, on the jumper harness. I don't think it's documented well if at all. I would not remotely go off this image alone but there's a real possibility that the documentation that places +5v on the outside of the APP sensor connector and low ref on the inside of the APP sensor connector could be pre-jumper and thus incorrect at the pedal, or vice versa.

@Captain Dave is your harness connected directly to the pedal or is there a little jumper harness in there? You might have to start chasing wire colors to ensure your issue isn't just crossed wiring.

 

[Captain Dave]

Now I'm even more confusd. From the DTC P2122 Accelerator Pedal Position (APP) Sensor 1 Circuit Low Voltage entry on Charm.Li, The APP sensor 1 signal voltage at rest position is near the low reference and increases as the pedal is actuated. The APP sensor 2 signal voltage at rest position is near the 5-volt reference and decreases as the pedal is actuated. But, conditions for setting the DTC are, The PCM detects that the APP sensor 1 voltage is less than 0.75 volt for more than 0.4 seconds.

If APP sensor 1 voltage is near the low ref at rest, shouldn't it normally be less than 0.75v??

Also, I do have a different APP sensor connector pinout. I would assume this pinout is more correct as it also shares the same wire colors as the Powertrain Management diagram linked and posted previously.
View attachment 53883


I'll make a pass at explaining how I think you should be testing each of these pins.

• Get Ready
  • Turn the key to ON (engine off).
  • Set your multimeter to DC volts (e.g., 20 VDC range).
  • Use a good chassis ground for your black lead.
• Check for 5 V Reference
  • Probe pin A - should read about 5 V.
  • Probe pin F - should also read about 5 V.
  • Probe pins B, C, D, E - should not show voltage.
• Check Grounds
  • Switch your meter to continuity mode.
  • Touch the probes together to confirm the meter works (mine beeps).
  • Keep the black lead on your chassis ground.
  • Probe pin C - should have continuity to ground.
  • Probe pin D - should also have continuity to ground.
  • Probe pins A, B, E, F - should not have continuity to ground... I think, but I haven't fully thought through how that'd play out.

If that's conclusive, great. If not, we'll probe somewhere else, probably on the TAC module or maybe at the PCM. Testing at the PCM will definitely require back probes.

Ok I tested everything as mentioned above and here are my results. Something is obviously not right.

Check for 5V reference
Pin A Tan 5.08v
Pin B Light Blue 4.5V jumping around some
Pin C Purple 0V
Pin D Brown 0V
Pin E 0V
Pin F White 0V

My multimeter (Gardner Bender GDT-311) does has a stand alone resistance test. I used the 200 Ohm setting.

A no reading
B no reading
C 84 ohms
D 84 ohms
E no reading
F no reading

From here I back probed the PCM

Pin 41 on the PCM 4.5 jumping around some
Pin 43 on the PCM 5.08V.

My car did have the jumper on it but I removed it. Before doing so I traced all of the wires and it did not look like they crossed at all. All the colors went straight through the connector and into the APP plug. Is it possible I missed something there and wired it wrong? The current issue was a problem before I removed the jumper.

 

[Captain Dave]

The "near Ref" might have to take into account the pull up/down voltage that most of these circuits use so the ECM can have a voltage to check the wiring. Maybe it has 1 volt when at rest? But that is just a guess.

Picture in post 115 says Pontiac G5 at the top so that is the base Cobalt, if it's even correct. I've said multiple of times on here that the SC version of everything needs to be used since it might differ from the Base. Is this the circuit that has the jumper that swaps some the wiring, so it is different from Base to SC? That might be the C201 connector. This car does have a jumper C201 to the APP? I think it might have the same connector end on it so it can be connected directly to the pedal but with wires crossed.

You are correct. The picture in post 115 is not the correct one. My car did have the jumper but I’m pretty sure it did not cross the wires. I think I had to use the jumper so that I would have the correct connector for the APP sensor on the throttle. I followed the wires and could not see anything that crossed or reversed the wires. This problem started before I removed the jumper as well.

 

[Captain Dave]

Documentation makes C201 look like a big connector ("I/P Harness to the Body Harness")- my first clue was that APP Sensor connector Pin F goes to B11 on the C201 connector. You do raise a good point, though, on the jumper harness. I don't think it's documented well if at all. I would not remotely go off this image alone but there's a real possibility that the documentation that places +5v on the outside of the APP sensor connector and low ref on the inside of the APP sensor connector could be pre-jumper and thus incorrect at the pedal, or vice versa.

@Captain Dave is your harness connected directly to the pedal or is there a little jumper harness in there? You might have to start chasing wire colors to ensure your issue isn't just crossed wiring.

View attachment 53884

Assuming that I am reading this picture correctly and the view of the plug is the APP plug on the pedal itself, my wiring is correct.

 

[Rauq]

Assuming all your connectors were plugged in, I think everything seems believable except for 0V on Pin F (is the wire really white, or is it white/black?)

I am still wondering if the documentation is reversing APP sensor 1 and sensor 2, based on the below description of operation:
The APP sensor 1 signal voltage at rest position is near the low reference and increases as the pedal is actuated. The APP sensor 2 signal voltage at rest position is near the 5-volt reference and decreases as the pedal is actuated.

If you push the gas pedal, does the voltage on Pin B (APP sensor 1 signal) decrease? That would confirm the documentation has those mixed.

But, 0V on Pin F is what's really suspect. That should be the second 5v reference to the APP sensor, and its absence does point directly to the issue I think you're seeing. Can you back probe C1-30 on the PCM and see if you have 5v there?

 

[Ross]

Okay, good testing Dave. My comments are in green, below.
This testing tells us that 5V circuit 2 is not working correctly in your car.
We need to start unplugging sensors off of circuit 2, and see if any of them allows circuit 2 to get up to 5V+.
PCM C1, Pin 30 is suppose to be the 5V+ for the dead circuit on your Accelerator Pedal.
Unplug the TAC=Throttle Actuator Control, and check the voltage on C1,30.
Unplug the MAP=Manifold Absolute Pressure, and check the voltage on C1, 30.

Ok I tested everything as mentioned above and here are my results. Something is obviously not right.

Check for 5V reference
Pin A Tan 5.08v -- Good, This is suppose to be 5V+.
Pin B Light Blue 4.5V jumping around some -- Good. This voltage should change as the accelerator pedal is pressed.
Pin C Purple 0V -- Good, this is suppose to be ground.
Pin D Brown 0V -- Bad. This is suppose to be ground. Well it is ground, so good, but bad that this circuit isn't working right now.
Pin E 0V -- Bad. This should read some voltage in the middle, and change as the pedal is pressed.
Pin F White 0V -- Bad. This should read 5V+

My multimeter (Gardner Bender GDT-311) does has a stand alone resistance test. I used the 200 Ohm setting.

A no reading -- probably good.
B no reading -- probably good, but if you set your meter to 2MOhm, you would probably get a reading. Should change with pedal position.
C 84 ohms -- That seems high to me... maybe an ohm or two, but 84 ohms makes me wonder if there is a ground issue.
D 84 ohms -- That seems high to me... maybe an ohm or two, but 84 ohms makes me wonder if there is a ground issue.
E no reading -- probably good, but if you set your meter to 2MOhm, you would probably get a reading. Should change with pedal position.
F no reading -- probably not meaningful test, as this pin isn't getting 5V+ like it should.

From here I back probed the PCM

Pin 41 on the PCM 4.5 jumping around some -- Good. This voltage should change as the accelerator pedal is pressed.
Pin 43 on the PCM 5.08V. -- Good, This is suppose to be 5V+.
Not sure why you tested Pin 41 and 43, and skipped C1,30. Pin 30 is suppose to be the 5V+ for the dead circuit on your Accelerator Pedal.

My car did have the jumper on it but I removed it. Before doing so I traced all of the wires and it did not look like they crossed at all. All the colors went straight through the connector and into the APP plug. Is it possible I missed something there and wired it wrong? The current issue was a problem before I removed the jumper.

The diagram of the 2.2L pontiac G5 did swap the 5V+ and ground for pins A& C on the Accelerator Pedal, when compared to the SC LSJ engine... but that would just make Pin B read backwards, and not cause the whole 5V system to be dragged down to 0V.

 

[Gtstorey]

Assuming that I am reading this picture correctly and the view of the plug is the APP plug on the pedal itself, my wiring is correct.
View attachment 53885

Connector end views are of the wiring connector, not the sensor they are being plugged into. If there is pigtail on the sensor, then you need to look at the pictures real close to confirm which connector you are looking at. But you should have 5v on two wires coming in anyway. Were the voltages in post 122 with the connector plugged up?

 

[Captain Dave]

Assuming all your connectors were plugged in, I think everything seems believable except for 0V on Pin F (is the wire really white, or is it white/black?)

I am still wondering if the documentation is reversing APP sensor 1 and sensor 2, based on the below description of operation:
The APP sensor 1 signal voltage at rest position is near the low reference and increases as the pedal is actuated. The APP sensor 2 signal voltage at rest position is near the 5-volt reference and decreases as the pedal is actuated.

If you push the gas pedal, does the voltage on Pin B (APP sensor 1 signal) decrease? That would confirm the documentation has those mixed.

But, 0V on Pin F is what's really suspect. That should be the second 5v reference to the APP sensor, and its absence does point directly to the issue I think you're seeing. Can you back probe C1-30 on the PCM and see if you have 5v there?

Pin F is a white wire with a black stripe.
Back probe on C1-30 is 0V at the PCM with the car switched on. Same test on C1-43 gives me the 5.08V. I will conduct the gas pedal test and post the results later today.

 

[Gtstorey]

Pin F is a white wire with a black stripe.
Back probe on C1-30 is 0V at the PCM with the car switched on. Same test on C1-43 gives me the 5.08V. I will conduct the gas pedal test and post the results later today.

So it's time to unplug the Tac module and Map sensor and see what you get. Diagram in post 98 says that is the 2 other sensor on 5v Ref #2.

 

[Robinjo]

My car did have the jumper on it but I removed it. Before doing so I traced all of the wires and it did not look like they crossed at all. All the colors went straight through the connector and into the APP plug. Is it possible I missed something there and wired it wrong? The current issue was a problem before I removed the jumper.

My jumper harness was the same thing. It was an A to A, B to B, etc. harness that only connected the male plug on the Cobalt harness to the male connection on the APP.

 

[Rauq]

So it's time to unplug the Tac module and Map sensor and see what you get. Diagram in post 98 says that is the 2 other sensor on 5v Ref #2.

I concur!

 

[Captain Dave]

Okay, good testing Dave. My comments are in green, below.
This testing tells us that 5V circuit 2 is not working correctly in your car.
We need to start unplugging sensors off of circuit 2, and see if any of them allows circuit 2 to get up to 5V+.
PCM C1, Pin 30 is suppose to be the 5V+ for the dead circuit on your Accelerator Pedal.
Unplug the TAC=Throttle Actuator Control, and check the voltage on C1,30.
Unplug the MAP=Manifold Absolute Pressure, and check the voltage on C1, 30.


The diagram of the 2.2L pontiac G5 did swap the 5V+ and ground for pins A& C on the Accelerator Pedal, when compared to the SC LSJ engine... but that would just make Pin B read backwards, and not cause the whole 5V system to be dragged down to 0V.

Okay, good testing Dave. My comments are in green, below.
This testing tells us that 5V circuit 2 is not working correctly in your car.
We need to start unplugging sensors off of circuit 2, and see if any of them allows circuit 2 to get up to 5V+.
PCM C1, Pin 30 is suppose to be the 5V+ for the dead circuit on your Accelerator Pedal.
Unplug the TAC=Throttle Actuator Control, and check the voltage on C1,30.
Unplug the MAP=Manifold Absolute Pressure, and check the voltage on C1, 30.


The diagram of the 2.2L pontiac G5 did swap the 5V+ and ground for pins A& C on the Accelerator Pedal, when compared to the SC LSJ engine... but that would just make Pin B read backwards, and not cause the whole 5V system to be dragged down to 0V.

Unplugged the TAC and still have 0V on C1-30.

Unplugged the MAP and still have 0V on C1-30.

The question about why I tested C1-41 and C1-43 but not C1-30 was to verify I was getting the 4.5V at the PCM. I did not think there should be voltage there but I understand why now. I didn’t test C1-30 because I knew it was at 0V from a previous test.

 

[Captain Dave]

Pin F is a white wire with a black stripe.
Back probe on C1-30 is 0V at the PCM with the car switched on. Same test on C1-43 gives me the 5.08V. I will conduct the gas pedal test and post the results later today.

When I push the throttle down, the 4.5V drops down to around 2.8V.

 

[Gtstorey]

Do you get 5V on either of the other sensors? If not, time to check and see if any of the 5v Ref2 feeds to the sensors are shorted to ground. With the sensors and the PCM disconnected check for continuity to ground of the C1 30 wire and the other 5v ref 2 wires to the sensors. Should be able to check from either end.

 

[Captain Dave]

Do you get 5V on either of the other sensors? If not, time to check and see if any of the 5v Ref2 feeds to the sensors are shorted to ground. With the sensors and the PCM disconnected check for continuity to ground of the C1 30 wire and the other 5v ref 2 wires to the sensors. Should be able to check from either end.

I have 5V on the MAP sensor and 5V on the TAC sensor. Actually 5V at two different locations on both plugs.

 

[Ross]

I have 5V on the MAP sensor and 5V on the TAC sensor. Actually 5V at two different locations on both plugs.

Really? Wow, you are getting 5V on reference 2 at the MAP and TAC, but not at the APP...
Time to check the wires within the red box...
With the key off, back probe C1,30 and C2,9 is the resistance measurement close to 0 ohms? Or is it broken inside the PCM?
How about the wire from C1,30 to F on the APP connector, is that wire near 0 ohms?

 

[Gtstorey]

I have 5V on the MAP sensor and 5V on the TAC sensor. Actually 5V at two different locations on both plugs.

Did you look at any of the diagrams to see if you have 5V on the correct wire coming from the 5v Ref#2? The secret to doing electrical diagnostics is to pay attention to details. But it is starting to sound like a failure of the 5v reference 2 bus inside of the ecm.

 

[Captain Dave]

Really? Wow, you are getting 5V on reference 2 at the MAP and TAC, but not at the APP...
Time to check the wires within the red box...
With the key off, back probe C1,30 and C2,9 is the resistance measurement close to 0 ohms? Or is it broken inside the PCM?
How about the wire from C1,30 to F on the APP connector, is that wire near 0 ohms?
View attachment 53888

C1-30 and C2-9 both do not give a reading at all with the key off. I am using the lowest ohm setting on my meter, grounding the black probe to a known solid ground, and using a back probe on the C1 and C2 connectors. My meter does not change from this setting. I did touch the leads together on the meter to make sure it was working and I did get a reading

C1-30 on the APP has no reading at all either.

C2-8 and C2-9 both have 5V with the key on.

 

[Captain Dave]

Did you look at any of the diagrams to see if you have 5V on the correct wire coming from the 5v Ref#2? The secret to doing electrical diagnostics is to pay attention to details. But it is starting to sound like a failure of the 5v reference 2 bus inside of the ecm.

I just went back and double checked. The 5V wire from Ref 2 seems correct. Blue with black stripe. I also checked the Ref 1 wire and it seems correct also. Gray wire.

 

[Captain Dave]

Since this issue has been going on for a while I would like to revisit a couple of things that may have been overlooked or forgotten about.

When I did my first start, the throttle was working correctly. At least enough for me to rev the engine a little. Once I got my brakes installed I needed to bleed the clutch and as I’m sure you know the bleeder is a pain to get to. I removed the fuse box to bleed the clutch. After everything was reinstalled the throttle did not work anymore.

I have pulled the fuse box out a couple of other times since to check for damaged pins or broken wires but can’t see anything wrong.

I have also replaced the entire entire gas pedal assembly, ran a new 18/6 wire from the APP to C1, and changed the throttle body.

When I switch the car on the plate inside of the throttle body does react to the car being switched on but does not respond to the pedal at all.

Another thing that is going on with the car but probably not the issue is that when I first start the car, the 4 way flashers and the horn goes off for about 20 seconds. The car starts and runs fine but maybe some sort of security feature that isn’t wired correctly. The main reason I am putting it on this post is the rare chance that it could be killing power to the APP as part of the security. Unfortunately I don’t remember if it was doing this when I started the car the first time when the pedal worked.