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Dad has a 2010 Malibu with a check engine light. I have tried 3 different scan tools, I get the same message that it’s unable to communicate. I have cleaned/inspected grounds and battery cables, I don’t see anything obvious under the hood. The car runs fine, everything works as expected. Only issue is the check engine light.
Anyone in readerland have any ideas where to begin looking?
I've troubleshot this before - it's most often the on-board wire clips have opened too far and need to be tightened up - dozens of videos on tightening them up...here's one....the point is to tighten up (close the openings) the clip openings.
Check the fuse for the power outlet (cell phone charger port) and there may also be a fuse for the OBD2 port. These both should be listed in the owners manual fuse box diagram.
Check the fuse for the power outlet (cell phone charger port) and there may also be a fuse for the OBD2 port. These both should be listed in the owners manual fuse box diagram.
I really hope that’s the issue. At one point my scan tool was able to pull codes. This is a recent issue.
Matt, on my 99 Chev PU, mine wasn't able to read either. The cause was the cigar lighter fuse was blown. Changed it out and the scan tool worked.
I realize your Chevy is 11 years newer but that's what I came across once. Good luck and let us know how it turns out.
Like so many things in life, this morning was a feeling of triumph, followed shortly by crushing defeat.
I pulled the ALDL connector from the dash. I used an old Delphi 150 male terminal to verify decent pin contact. One pin did feel loser than the others, I replaced that terminal. Success! I was able to retrieve the codes. The one that caught my attention was the P1174, cylinder imbalance. This code was in the car several months ago, based on a “YouTube” certified tech video, I replaced both O2 sensors. I don’t recall if I was able to clear the code at that time due to the scan tool not communicating. I was able to clear it this time. The car also had some other older BCM codes.
Now, the defeat part.
On a test drive, I heard the scan tool beep, and a message saying communication lost. Great big steaming piles of horse excrement!! Guess that wasn’t the issue.
IMO, you replaced one pin but you didn't replace or tighten other pins; in particular, since the one loose pin, as you stated yourself, was the issue. Replace or tighten the other pins my suggestion.
Those lost communication and CAN bus codes are where to go first. Use an ohmmeter and measure resistance from pins 6 and 14. It should be 60 ohms if network is in complete.
Matt - I have a 2003 Ford F-250 diesel (195K miles) w/ significant routine major & minor maintenance during the past 20 yrs. of ownership. Something I learned years ago is the ability to permanently clear memory & codes to provide the ability to start fresh. The chap in this video has some excellent videos on Ford truck maintenance. This is the procedure I've employed and it works flawlessly (on my truck). I've had to replace the fuse box (windshield water leakage destroyed it) & a couple items over the years where I wanted to ensure all "memory" was cleared (not simply the codes themselves). This allowed me to start fresh. The vehicle then learns the idle trim, fuel ratios, shift points, etc. I can't speak whether it will work for you, but you have enough knowledge to know how this works and why this works. Whether you call modules PCM, ECM, etc. they all talk with one another along the CAN bus and this process clears the memory maintained for those modules communication. Just thought I'd throw that out there for you in the off-chance it may be something for you to consider and ponder.
Well dang. How would you troubleshoot anything in the future if the memory and codes were permanently cleared?
Not certain that was "exactly" how you intended to ask your question, since you would still be able to troubleshoot anything in the future but memory of anything "prior" to a clear memory would be lost. A good analogy is likened to clearing CMOS on your computer.
Well dang. How would you troubleshoot anything in the future if the memory and codes were permanently cleared?
Troubleshooting a problem in the future would be done when it throws a code. Maybe I'm over-simplifying it in my thought process, since I'm not a mechanic.
I'll use the example of fixing a "Service Stabilitrak soon / reduced engine power" dash message (I don't recall the codes it put out). The codes indicated that the throttle position sensor was causing the issue. Since it was a drive-by-wire throttle body, I knew that the sensor was no longer recognizing proper accel pedal input and that the throttle body needed to be replaced. The TPS was not a serviceable item. After replacement, I cleared the codes. Test drove, issue never returned.
In this situation, what good would having those codes stored in memory serve? The problem was fixed.
I checked every fuse I could find. The power port in the ashtray does have power.
I suppose I’m going to have to get a real service manual for this car, and some of the other junk in our fleet. I really don’t like dragging a laptop around, I’d prefer a REAL paper book. The cheap chiltons books are worthless in my opinion, and this car is too new for old school books.
IMO, you replaced one pin but you didn't replace or tighten other pins; in particular, since the one loose pin, as you stated yourself, was the issue. Replace or tighten the other pins my suggestion.
all the other pins were tight. Just the one had a sloppy fit.
Those lost communication and CAN bus codes are where to go first. Use an ohmmeter and measure resistance from pins 6 and 14. It should be 60 ohms if network is in complete.
February 2nd, 2023, 10:10 AM
