P0404 EGR Any definite conclusions?
#71
07-24-2022, 10:12 AM
I think that this guy has the same EGR valve that you do so maybe his cleaning process can help answer that question:
https://m.youtube.com/watch?v=bt5lRTt6BsU
Most testing routines involve commanding the EGR valve with a bidirectional scan tool and monitoring the results but of course most do not have this capability. You can measure a few things to check some of the circuit with a simple digital meter. Do you have a 5 wire valve? Do you have a digital meter?
The PCM is reporting EGR position values that don’t make sense but without testing you don’t know if the valve has failed/dirty or if something in the circuit has failed.
George
https://m.youtube.com/watch?v=bt5lRTt6BsU
Most testing routines involve commanding the EGR valve with a bidirectional scan tool and monitoring the results but of course most do not have this capability. You can measure a few things to check some of the circuit with a simple digital meter. Do you have a 5 wire valve? Do you have a digital meter?
The PCM is reporting EGR position values that don’t make sense but without testing you don’t know if the valve has failed/dirty or if something in the circuit has failed.
George
Last edited by GeorgeLG; 07-24-2022 at 10:15 AM.
#72
07-24-2022, 10:45 PM
I think that this guy has the same EGR valve that you do so maybe his cleaning process can help answer that question:
https://m.youtube.com/watch?v=bt5lRTt6BsU
Most testing routines involve commanding the EGR valve with a bidirectional scan tool and monitoring the results but of course most do not have this capability. You can measure a few things to check some of the circuit with a simple digital meter. Do you have a 5 wire valve? Do you have a digital meter?
The PCM is reporting EGR position values that don’t make sense but without testing you don’t know if the valve has failed/dirty or if something in the circuit has failed.
George
https://m.youtube.com/watch?v=bt5lRTt6BsU
Most testing routines involve commanding the EGR valve with a bidirectional scan tool and monitoring the results but of course most do not have this capability. You can measure a few things to check some of the circuit with a simple digital meter. Do you have a 5 wire valve? Do you have a digital meter?
The PCM is reporting EGR position values that don’t make sense but without testing you don’t know if the valve has failed/dirty or if something in the circuit has failed.
George
#73
07-24-2022, 10:50 PM
Oh and I've cleaned the valve before but didn't fix the issue. So I'm focusing on cleaning the ports as well at this point. Just ruling things out one by one.
#75
07-25-2022, 04:01 PM
The pintle moves with power applied. Also tested the voltage range on pintle sensor by moving it manually and it's .67v when closed, 4.9v at full open. What I read said closed should be .6 to .9v so that's good. Full open it should be about 4.5v. Can my slightly high voltage mean the pintle position sensor is bad? Wishful thinking I know, but running out of options.
#76
07-25-2022, 04:51 PM
Ok so I started over from scratch and found something strange. When I test for 12v on red wire with egr unplugged I get 11.9v. When it's plugged in I don't even get 1v. Thought my back probe wasn't connecting so I tried it on the 5v reference and it read perfect. So I put probe back on red wire, then unplugged the connector, and reading goes up to 11.9v. Plug it in, voltage drops back to under 1v. Is that normal?
#77
07-25-2022, 06:57 PM
Couple of things:
There needs to be three things working correctly in the EGR circuit:
1) The EGR valve itself reacts correctly to the various conditions presented to it on the red and white wires and reports its position correctly on the brown wire when the proper 5v ref and low ref signals are applied to gray and black wires for the position sensor
2) The wiring between the egr and the pcm is in good shape so the voltage and signals get from one end to the other
3) The pcm presents the correct voltages and values and correctly reads the valve position.
So this can be broken down into a few steps. Ill just start from the beginning because I dont know where you are measuring all of these values and applying voltages. I know that you have done some of this already so great.
The red and white wires control the valve position. I am pretty sure that the 12v side on red is fixed and then the valve position is changed by varying the voltage on the white wire, changing the net voltage to the valve. There is a possibility that I have this reversed, Its easy to verify. So it depends on where your measuring. Is this right at the valve or back at the PCM? Where are you placing the meter ground probe, battery ground or the egr white wire? If its red to white with the meter then the result can vary somewhere between net zero and net 12v. if its battery ground to red and or white, one wire wont change and the other one will. So the first part of this is:
Does the pintle position change when net voltage varies on red and white directly to the valve, and when connected back up is the pcm able to do this correctly through the wiring to the valve?
Next up is the sensor output. Does 5V ref and lo ref make it to the gray and black wires and then does the output voltage on brown vary between 0 and 5v as the pintle position changes, first at the valve and then up at the pcm. Do you have a scanner that at least reports the valve position?
On all this stuff voltages can look OK until the whole circuit is connected at which point, faulty loads and bad wires reveal themselves. That's why the best measurements are almost always connected, operating and back probed.
So in answer to your red wire voltage, what is the voltage plugged and unplugged with the meter black cable on battery ground?
As far as 4.5 vs 4.9 volts on the signal output i dont know for sure but my educated guess is that its good.
George
There needs to be three things working correctly in the EGR circuit:
1) The EGR valve itself reacts correctly to the various conditions presented to it on the red and white wires and reports its position correctly on the brown wire when the proper 5v ref and low ref signals are applied to gray and black wires for the position sensor
2) The wiring between the egr and the pcm is in good shape so the voltage and signals get from one end to the other
3) The pcm presents the correct voltages and values and correctly reads the valve position.
So this can be broken down into a few steps. Ill just start from the beginning because I dont know where you are measuring all of these values and applying voltages. I know that you have done some of this already so great.
The red and white wires control the valve position. I am pretty sure that the 12v side on red is fixed and then the valve position is changed by varying the voltage on the white wire, changing the net voltage to the valve. There is a possibility that I have this reversed, Its easy to verify. So it depends on where your measuring. Is this right at the valve or back at the PCM? Where are you placing the meter ground probe, battery ground or the egr white wire? If its red to white with the meter then the result can vary somewhere between net zero and net 12v. if its battery ground to red and or white, one wire wont change and the other one will. So the first part of this is:
Does the pintle position change when net voltage varies on red and white directly to the valve, and when connected back up is the pcm able to do this correctly through the wiring to the valve?
Next up is the sensor output. Does 5V ref and lo ref make it to the gray and black wires and then does the output voltage on brown vary between 0 and 5v as the pintle position changes, first at the valve and then up at the pcm. Do you have a scanner that at least reports the valve position?
On all this stuff voltages can look OK until the whole circuit is connected at which point, faulty loads and bad wires reveal themselves. That's why the best measurements are almost always connected, operating and back probed.
So in answer to your red wire voltage, what is the voltage plugged and unplugged with the meter black cable on battery ground?
As far as 4.5 vs 4.9 volts on the signal output i dont know for sure but my educated guess is that its good.
George
#78
07-25-2022, 09:19 PM
Yes you had me go through all the isolated tests with harness unplugged from pcm and egr valve, to make sure of continuity and no shorts on the wires. All tests passed. But not sure we ever went through actually testing voltages with everything plugged in.
All the following were done with key in on position, vehicle not running.
When testing the red wire, I had multimeter grounded at battery. With the EGR unplugged I got 11.9v on the red wire at connector. With EGR plugged in, I got less than 1 volt (didn't note exactly what it was but it was less than 1). I unplugged the EGR with tester still connected, and as soon as it was unplugged the voltage would go up to 11.9v.
When I checked for pintle movement, I ran ground from sensor ground at harness to battery (it was the only ground wire I saw in the harness schematic). Then I briefly jumped the red wire to battery positive a few times to see if pintle opened, which it did. Not sure I did this right.
5v reference was also measured with meter negative on battery, egr plugged in.
For pintle position voltage range, I put meter positive to pintle position signal wire, not sure of color but it was the center wire. Meter negative to battery. Then I manually opened and closed the pintle with a screwdriver while watching the voltage change, which appears to be within spec.
Not sure I answered everything....Will have to read your reply again....
All the following were done with key in on position, vehicle not running.
When testing the red wire, I had multimeter grounded at battery. With the EGR unplugged I got 11.9v on the red wire at connector. With EGR plugged in, I got less than 1 volt (didn't note exactly what it was but it was less than 1). I unplugged the EGR with tester still connected, and as soon as it was unplugged the voltage would go up to 11.9v.
When I checked for pintle movement, I ran ground from sensor ground at harness to battery (it was the only ground wire I saw in the harness schematic). Then I briefly jumped the red wire to battery positive a few times to see if pintle opened, which it did. Not sure I did this right.
5v reference was also measured with meter negative on battery, egr plugged in.
For pintle position voltage range, I put meter positive to pintle position signal wire, not sure of color but it was the center wire. Meter negative to battery. Then I manually opened and closed the pintle with a screwdriver while watching the voltage change, which appears to be within spec.
Not sure I answered everything....Will have to read your reply again....
#79
07-25-2022, 10:27 PM
Lets stick with the red and white wire which control the valve movement. Keep your meter black wire on the battery ground as before and with the egr valve unplugged measure the red wire then the white wire, then measure the red wire again and put the meter black cable on the white wire. Then plug in the egr valve and repeat. I think that this is where the problem will be. Based on what you tell me then we may need to measure up at the pcm under a load
George
George