error codes

Jim624

2005 GMC envoy 6 cylinder. Got the down arrow/engine light. I would have to pull over and turn it off and then start it again…sometimes it ran fine but usually it would do the same thing in a few minutes. The ONLY thing that I can correlate it too is the A/C was on when the down arrow came on on. So, I figured the A/C was putting to much of a load on the engine. When the AC is off it does fine. I changed the airfilter, cam sensor crankshaft sensor (did the relearn on my scanner) Changed the ignition coils, plugs, cleaned the throttle body real good. And today I was driving and it did the same thing with the ac on. (Note: the regular engine light has been on the entire time, unless I clear it with the scanner, but that only last through one restart) Still throwing error 0340 and 0107…. I am going to replace te mAP sensor, but how the hell do I get rid of the 0340

thecardoc3

The answer to your question is, "Test and prove what is wrong" and then fix it. A DTC (Diagnostic Trouble Code) is the identification number of a test that a computer has run that has failed. A DTC doesn't tell you what part is bad, it only tells you what test failed. Now sure a test can fail because a part is bad, but it can also fail for a number of other reasons. For example, the P0340 sets when the engine control module doesn't see the camshaft sensor signal for a minimum of three seconds while it can see the crankshaft sensor signal. Did you test to see if there is 12v at the sensor Red wire pin A? Is there voltage on the Brown/White wire pin C? You need to check it disconnected, connected key on engine off, and with the engine running and post what you found. Is there ground "0 volts" on the Pink/Black wire pin B when both the engine is running as well as key on-engine off? In the shop I would use an oscilloscope to make these measurements because I want to see the actual square wave signal produced by the sensor. One or more of these measurements may have to be repeated at the engine control module, or depending on how difficult to access the camshaft sensor is you could choose to start there at pins, 44, 26, and 15 of connector #2.

The P0107 should be approached the same way. The P0107 means that the MAP sensor voltage is too low at the computer pin 46 Light Green wire connector #2. The testing would otherwise be the same just some of the test values would be different. There should be 5v on the grey wire pin C at the sensor, 0v at the Orange/Black wire pin A and a varying voltage with the engine running on the Light Green wire pin B. The voltage on pin B will usually be close to 4v key on engine off, and around 1v with the engine idling. This is information that can be seen with a scan tool. What you need to do is prove that the voltage you measure at the sensor and the computer are the same as what is displayed in the scan data.