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

[Captain Dave]

Yes if there is a short to ground you won’t get a voltage reading. That circuit is designed to protect it’s self if there is a short to ground, although the protection isn’t 100% and occasionally will still damage it if repeatedly shorted to ground. Take the diagram that Ross posted and check for 5v one at a time at each sensor associated either the missing 5v. If you don’t get 5v, disconnect it and move on to the next one and repeat until they are all disconnected. If you don’t get 5v at any of them check at the pcm. If still no voltage, them I would consider cutting the wire to determine if there is 5v short to ground within the wiring harness. If still no 5v then the pcm is probably bad.

Could I just start with cutting the wire to determine if there is a short to ground? Seems like a much easier test than to disconnect all of the sensors.

 

[Gtstorey]

Could I just start with cutting the wire to determine if there is a short to ground? Seems like a much easier test than to disconnect all of the sensors.

You can but if you get the 5v after cutting the wire, you’ll still have to go through the process to eliminate a bad sensor and still have to fix the cut wire.

 

[Captain Dave]

Ok so I went ahead and cut the wire from the PCM. Stop #7 which is one of the 5V supplies coming out of the PCM and going to the PPs. After cutting the wire there is still zero current coming from the PCM. The other 5V source still shows 5V out of the PCM.

 

[Gtstorey]

I should have looked at the wiring diagram Ross posted a little closer. The connection to the other sensors is within the PCM so there could still be a short to ground on one of them.

I'm not sure what "Stop #7" is referring too. Is the problem with 5v reference 1 or 2?

 

[Gtstorey]

And remember that if we can't see whatever wiring diagram or pinout you are looking at if it's not posted here. We don't have all of this stuff memorized.

 

[Captain Dave]

I should have looked at the wiring diagram Ross posted a little closer. The connection to the other sensors is within the PCM so there could still be a short to ground on one of them.

I'm not sure what "Stop #7" is referring too. Is the problem with 5v reference 1 or 2?

That was supposed to say spot #7 on the PCM plug. The issue is with sensor 2.

 

[Captain Dave]

Where is the TAC module located? It looks like the plug is the same as the one that plugs into the throttle body and the plug that goes to the top of the engine. They look identical minus wire color.

 

[Captain Dave]

Sorry for all of the questions. I really have no clue what I am doing when it comes to all of the wiring and electronics.

 

[Rauq]

TAC module is the throttle body, Throttle Actuator Control I believe. If you have +5V on C1-30 (+5V Ref 2 to APP Sensor 1) but you don't have +5V on C1-43 (+5V Ref1 to APP Sensor 1), then you probably have a short on one of the other +5V Ref1 connections (what you would refer to as Spots #1-6, but more objectively C2-5/4, C1-17/47, C3-22, or C2-6.

C2-6 goes to the TAC.

Not sure what your question is about the TAC module- the throttle body, coil harness, and LSJ-specific engine-to-body harness connection all use the same 8-pin connector and are in the same general vicinity of each other, but I think if you got those confused we wouldn't be troubleshooting where we are.

 

[Captain Dave]

TAC module is the throttle body, Throttle Actuator Control I believe. If you have +5V on C1-30 (+5V Ref 2 to APP Sensor 1) but you don't have +5V on C1-43 (+5V Ref1 to APP Sensor 1), then you probably have a short on one of the other +5V Ref1 connections (what you would refer to as Spots #1-6, but more objectively C2-5/4, C1-17/47, C3-22, or C2-6.

C2-6 goes to the TAC.

Not sure what your question is about the TAC module- the throttle body, coil harness, and LSJ-specific engine-to-body harness connection all use the same 8-pin connector and are in the same general vicinity of each other, but I think if you got those confused we wouldn't be troubleshooting where we are.

Ok so yet another name for the TPS I guess. lol. I have 5V on C1-43 but nothing on C1-30. I do have 5V on two different locations of the TAC harness, I have 5V on the coolant temp sensor, I have 5 volts on the MAF, and I have 5V on the MAP sensor.

 

[Captain Dave]

TAC module is the throttle body, Throttle Actuator Control I believe. If you have +5V on C1-30 (+5V Ref 2 to APP Sensor 1) but you don't have +5V on C1-43 (+5V Ref1 to APP Sensor 1), then you probably have a short on one of the other +5V Ref1 connections (what you would refer to as Spots #1-6, but more objectively C2-5/4, C1-17/47, C3-22, or C2-6.

C2-6 goes to the TAC.

Not sure what your question is about the TAC module- the throttle body, coil harness, and LSJ-specific engine-to-body harness connection all use the same 8-pin connector and are in the same general vicinity of each other, but I think if you got those confused we wouldn't be troubleshooting where we are.

Not really sure how to read this. Again I am very new to wiring and wiring diagrams but I’m learning fast. Thrown into the fire. lol.

+5V Ref1 connections (what you would refer to as Spots #1-6, but more objectively C2-5/4, C1-17/47, C3-22, or C2-6.

C-2 and C-3 are referring to the other two connectors on the PCM right? C-2-5/4 means pin #5 and #4? How do I check that these are working correctly?

 

[Rauq]

C2-5 would be Pin 5 on the C2 connector, C1-17 is pin 17 on the C1 connector, etc.

Ok so yet another name for the TPS I guess. lol. I have 5V on C1-43 but nothing on C1-30. I do have 5V on two different locations of the TAC harness, I have 5V on the coolant temp sensor, I have 5 volts on the MAF, and I have 5V on the MAP sensor.

That was supposed to say spot #7 on the PCM plug. The issue is with sensor 2.

Going to need some clarification here, I'm sure some of this has been answered previously.

The issue is with sensor 2- this is based on what, the DTC? You cut the tan wire at C1-43 and you don't have +5v on the PCM side of that cut wire?

But if you have 5V on C1-43 and nothing on C1-30 then according to the diagrams at least you should be getting +5v to APP Sensor 2 but not to APP Sensor 1. Not sure where we're crossing metaphorical wires here.

If you have +5v at two places on the TAC harness, then you have +5v on both the +5v Ref 1 and +5v Ref 2 circuits.

The coolant temp sensor and MAF don't share +5v Ref 1 or 2, but they do share low ref. The MAP (assuming it's actual MAP and not Baro or SCIP) is on +5v Ref 2.

You said you cut C1-30 and don't have voltage- how are you measuring to see if you have +5v on the other pins?

It's hard to test because if you pull connectors to hit PCM pins, you're also probably pulling supply voltage to the PCM and won't have voltage to measure. If you are poking through wire insulation, not my favorite way of doing things, but it's your car. If you have a back probe, we can work with that. But so far this seems generally confusing and unclear.

Here's my request:
-Load this diagram
-Connect all the PCM connectors
-Turn the key to the ON position
-Back probe every +5v Ref (1 and 2) with a multimeter and record if you have voltage to ground
-Back probe every Low Ref with a multimeter and record if you have voltage and/or continuity to ground

Post up your results and I'll think some more. I'm no electrical expert but I did not sleep at a Holiday Inn Express last night.

 

[Gtstorey]

Ok so yet another name for the TPS I guess. lol. I have 5V on C1-43 but nothing on C1-30. I do have 5V on two different locations of the TAC harness, I have 5V on the coolant temp sensor, I have 5 volts on the MAF, and I have 5V on the MAP sensor.

Use the names,

Ok so yet another name for the TPS I guess. lol. I have 5V on C1-43 but nothing on C1-30. I do have 5V on two different locations of the TAC harness, I have 5V on the coolant temp sensor, I have 5 volts on the MAF, and I have 5V on the MAP sensor.

Use the names, pin# and Connector # as shown on a posted wiring diagram. That way we can all be sure that we are all talking about the same thing.

 

[Gtstorey]

Two spots of the TAC harness could mean 5v on the feed side and 5v on the signal side if this sensor puts out 5v at no throttle. I assume this TAC works by increasing voltage on 1 sensor and decreasing on the other.

Captain Dave, give us exact pins and names as shown in Ross's wiring diagram. Otherwise, we will waste a lot of time trying to interpret what you are telling us. Are you getting 5V on both pins G & B (Image is a little fuzzy, so it would be nice to getter a clearer one)?

 

[Captain Dave]

C2-5 would be Pin 5 on the C2 connector, C1-17 is pin 17 on the C1 connector, etc.



Going to need some clarification here, I'm sure some of this has been answered previously.

The issue is with sensor 2- this is based on what, the DTC? You cut the tan wire at C1-43 and you don't have +5v on the PCM side of that cut wire?

But if you have 5V on C1-43 and nothing on C1-30 then according to the diagrams at least you should be getting +5v to APP Sensor 2 but not to APP Sensor 1. Not sure where we're crossing metaphorical wires here.

If you have +5v at two places on the TAC harness, then you have +5v on both the +5v Ref 1 and +5v Ref 2 circuits.

The coolant temp sensor and MAF don't share +5v Ref 1 or 2, but they do share low ref. The MAP (assuming it's actual MAP and not Baro or SCIP) is on +5v Ref 2.

You said you cut C1-30 and don't have voltage- how are you measuring to see if you have +5v on the other pins?

It's hard to test because if you pull connectors to hit PCM pins, you're also probably pulling supply voltage to the PCM and won't have voltage to measure. If you are poking through wire insulation, not my favorite way of doing things, but it's your car. If you have a back probe, we can work with that. But so far this seems generally confusing and unclear.

Here's my request:
-Load this diagram
-Connect all the PCM connectors
-Turn the key to the ON position
-Back probe every +5v Ref (1 and 2) with a multimeter and record if you have voltage to ground
-Back probe every Low Ref with a multimeter and record if you have voltage and/or continuity to ground

Post up your results and I'll think some more. I'm no electrical expert but I did not sleep at a Holiday Inn Express last night.

Thanks for taking the time to write all of this up.

**The issue is with sensor 2- this is based on what, the DTC? You cut the tan wire at C1-43 and you don't have +5v on the PCM side of that cut wire?

The DTC is a 2122 (Throttle/Pedal Position Sensor/Switch D Circuit Low). The tan wire at C1-43 has 5V. The white wire at C1-30 does not have any voltage. Both back probed at the PCM.

**But if you have 5V on C1-43 and nothing on C1-30 then according to the diagrams at least you should be getting +5v to APP Sensor 2 but not to APP Sensor 1. Not sure where we're crossing metaphorical wires here.

I am not 100% sure that the picture I have identifying APP sensor 1 and 2 is correct.

**The coolant temp sensor and MAF don't share +5v Ref 1 or 2, but they do share low ref. The MAP (assuming it's actual MAP and not Baro or SCIP) is on +5v Ref 2.

After looking at the wiring diagram again I see that the MAF and coolant temp dont share the +5v Ref 1 or 2. (Still learning how to read these diagrams).

**You said you cut C1-30 and don't have voltage- how are you measuring to see if you have +5v on the other pins?

It's hard to test because if you pull connectors to hit PCM pins, you're also probably pulling supply voltage to the PCM and won't have voltage to measure. If you are poking through wire insulation, not my favorite way of doing things, but it's your car. If you have a back probe, we can work with that. But so far this seems generally confusing and unclear.

I am measuring the voltage on the other pins by unplugging the connecter and checking voltage going to the connecter.

**-Back probe every +5v Ref (1 and 2) with a multimeter and record if you have voltage to ground
-Back probe every Low Ref with a multimeter and record if you have voltage and/or continuity to ground

Now the true "I don't know what the hell I am doing" comes out...can you be more specific on the proper way to conduct these tests? Pretend you are talking to a kindergartener. lol. How exactly do I test for voltage to ground and voltage and/or continuity to ground? I tried to research it but I did not get a clear answer. I just dont want to waste a bunch of time doing things the wrong way.

 

[Captain Dave]

Two spots of the TAC harness could mean 5v on the feed side and 5v on the signal side if this sensor puts out 5v at no throttle. I assume this TAC works by increasing voltage on 1 sensor and decreasing on the other.

Captain Dave, give us exact pins and names as shown in Ross's wiring diagram. Otherwise, we will waste a lot of time trying to interpret what you are telling us. Are you getting 5V on both pins G & B (Image is a little fuzzy, so it would be nice to getter a clearer one)?

I am not sure what pins G and B are? Which diagram are you looking at?

 

[Ross]

Click on the From Charm Li, link to get a clearer picture. The image got fuzzy when I added my red boxes.

 

[Ross]

The orange squares are all 5V reference 1.
The green squares are all 5V reference 2.
On the Throttle Actuator Control, sensor 1 is on 5V reference 1.
On the Accelerator Pedal Position, sensor 1 is on 5V reference 2.

Way to be consistent, Chevrolet! (Sarcasm) Maybe there is a real reason for this, but I did find it a bit confusing.

This is a little further down the link from Charm Li.

 

[Rauq]

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.

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.

 

[Gtstorey]

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.