Problems pulling DTC codes, please help
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Joined: Sep 2015
Posts: 88
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From: Clermont Florida
Problems pulling DTC codes, please help
Hi guys.
I've got a 2002 Vert. Last night the engine light came on and stayed on. Seemed to run ok, engine temp was fine as well as oil pressure. Restarted a few times and engine light is still on. This morning I went to pull the DTC codes using the instructions found here on the forum. Well, I got them to come up, once! I didn't realize they would scan so quickly, too fast to write them down. Once it went thru the sequence (there were a BUNCH of codes) it went to manual. I pressed the E/M button to get out of Manual thinking I could go back into auto mode and take pics of them all as they scrolled. Well, now I can't seem to get it back into Auto mode. The screen just stays blank. Will it only show the codes once? How do I get back in, and when I do, what's the best way to get the codes so I can figure out what they mean? Thanks guys for the help!
I've got a 2002 Vert. Last night the engine light came on and stayed on. Seemed to run ok, engine temp was fine as well as oil pressure. Restarted a few times and engine light is still on. This morning I went to pull the DTC codes using the instructions found here on the forum. Well, I got them to come up, once! I didn't realize they would scan so quickly, too fast to write them down. Once it went thru the sequence (there were a BUNCH of codes) it went to manual. I pressed the E/M button to get out of Manual thinking I could go back into auto mode and take pics of them all as they scrolled. Well, now I can't seem to get it back into Auto mode. The screen just stays blank. Will it only show the codes once? How do I get back in, and when I do, what's the best way to get the codes so I can figure out what they mean? Thanks guys for the help!
Thread Starter
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Joined: Sep 2015
Posts: 88
Likes: 26
From: Clermont Florida
It showed I have 16 codes all together, and all are in History, not current. 15 of the codes are with the left and right door control modules. They are almost the same ones left and right. Should I just clear these and see if they come back? Almost seems like faults that would have occurred when unplugging a door wiring harness? Like door lock switch fault, window up and down switch faults, 12v power feed #1 & #2 faults, mirror faults, then Normal software function, history status upon ignition cycling. So, would you just clear these faults?
The one I'm concerned about is P0171 H. Fuel Trim System Lean Bank 1. It shows as in history. Would this have caused the "check engine" light to come on? Should I clear it?
If I do clear it, is it possible the "check engine" will go out?
Thanks for all of the help guys! You Rock!
Jerry
Thread Starter
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Joined: Sep 2015
Posts: 88
Likes: 26
From: Clermont Florida
Most code when pulled with the key ON and engine OFF will show as H. That is because most of the sensors that generate codes that would show as C only do so when the engine is running and the computer converts the codes to H once the engine is turned OFF.
Do NOT discount H codes. They are an audit trail of events that have occurred and can be very helpful when diagnosing a problem.
The codes that show from the left and right door control modules are usually indicative of a battery related problem. Have you removed or replaced the cars battery recently? When connecting the battery cables you often cause the voltage to be applied and broken several times while tightening the battery cables. This drives the sensors in the car nuts, especially the dor control modules.
The cause of the check engine light is the P0171 code.Clearing the code will erase the code from memory but it does not fix the problem. If the problem is still there then the CEL and code will return.
When you clear codes related to the PCM that causes the Emissions Ready conditions to be set to NOT Ready. The C5 built in reader does NOT report those.
You need to either have your own emissions code reader or visit your favorite parts store to have them check for you. 
To cause the NOT Ready's to be set to Ready you need to drive the car for somewhere between 50 and 150 miles under varying conditions (stop and go, highway etc) and also requires several ignition cycles in the mix.
Getting back to the P0172, it is most likely being cause by an air leak after the MAF. Check all the connections if the plumbing from the MAF to the intake for loose clamps, cracks in the tubes, etc. Also check the lines for the PCV valve. Those lines tend to rot due to heat, oil and time. That can also cause the P0171....
Lastly it is possible to pull codes with the engine running. Doing so allows you to see codes that are C. To pull codes with the engine running you need to clear all messages displayed in the DIC. Use the reset key to help do this. Then pull codes an normal.
Do NOT discount H codes. They are an audit trail of events that have occurred and can be very helpful when diagnosing a problem.
The codes that show from the left and right door control modules are usually indicative of a battery related problem. Have you removed or replaced the cars battery recently? When connecting the battery cables you often cause the voltage to be applied and broken several times while tightening the battery cables. This drives the sensors in the car nuts, especially the dor control modules.
The cause of the check engine light is the P0171 code.Clearing the code will erase the code from memory but it does not fix the problem. If the problem is still there then the CEL and code will return.
When you clear codes related to the PCM that causes the Emissions Ready conditions to be set to NOT Ready. The C5 built in reader does NOT report those.
You need to either have your own emissions code reader or visit your favorite parts store to have them check for you. To cause the NOT Ready's to be set to Ready you need to drive the car for somewhere between 50 and 150 miles under varying conditions (stop and go, highway etc) and also requires several ignition cycles in the mix.
Getting back to the P0172, it is most likely being cause by an air leak after the MAF. Check all the connections if the plumbing from the MAF to the intake for loose clamps, cracks in the tubes, etc. Also check the lines for the PCV valve. Those lines tend to rot due to heat, oil and time. That can also cause the P0171....
Lastly it is possible to pull codes with the engine running. Doing so allows you to see codes that are C. To pull codes with the engine running you need to clear all messages displayed in the DIC. Use the reset key to help do this. Then pull codes an normal.
