Bruze

Ha, well I knew it had to happen sooner or later -- I'm surprised it didn't happen sooner. Just last week I commented on some thread that my '07 with 34k miles has been trouble-free and that everything works.

Well it ain't no more. The engine light came on after I started it last night and was heading home. No weird symptoms and no DIC messages.

I plugged my cheap scanner in and got "U0073" and "U0073 P." I Googled them and got a bunch of stuff, wiring problems, loose connectors, etc. It's all jibberish to me.

What to do next? My go-to buddy is out of town for the week.

CHEV AGAIN

1bdvet

My 05 last month threw on the check engine light after refueling. So I bought new gas cap, and the check engine light went out, for about month, and last week, it came back on again. So I just took a piece black tape over the check engine light. You know the old saying, out of sight out of mind.

Well today drive, the light went out again. I'll see how long with this time it stays off, have nothing on the DIC, and car has power.

So I'll just leave it alone, till the car needs to go to the shop for repairs.

HBsurfer

I have nothing to offer other than that sucks. I'll be following along to see what the fix is. I am sure somebody here will point you to a cure. Good luck!!!

Bruze

Ha, yes I've read the countless threads here about the bizarre things that happen when the battery goes out on these cars. It happened to me four years ago -- wouldn't crank, DIC went crazy, lights flashing, etc. Luckily I was in my front yard.

Although the battery is four years old, it is always on a tender when home. I load-tested it this spring and it was still excellent. So, who knows?

Nah, I can't go that route. I have to have things correct. It's part of my (flawed) perfectionism.

Thanks Tony. Do you think the light would go out if I changed my underwear? Last time I changed them was when I bought the new battery. Maybe they're due.

HBsurfer

Don't panic and start making crazy decisions. I am sure your underwear are fine as is.

rkj427

Bruce, there is a GM Service Document with a lot of information on it related to U0073.

Majority deal with intermittent connections and power loss, as U codes typically refer to Can Bus communication. Attempted to save it as photos, would have inserted them here, but I stopped at 14.

Check underhood for any "chafed" wires on the intake manifold area first, easiest to see. Unless you are going to tackle this yourself, better off to wait for "your guy."

Bruze

Thanks for the comment. I also saw that TSB while Googling around, and it included '07s.

I will look tomorrow although I won't expect to see anything obvious. Everything is bone stock and the engine and surround looks pretty much like it did when new. But, that doesn't necessarily mean anything.

Bruze

Yeah, yer probably right. I often panic and go off the deep end, and end up doing something that I later regret. I'll hold off on the underwear change.

Yer a great buddy to have, always the one with the level head and somehow coaxing me off the window ledge.



Supposed to get a lot of rain tomorrow so the car stays in the barn. Maybe on Wednesday I'll stop at a local garage where I know the guys and have them check it.

Landru

Parked in a barn?
Given nature of code, wiring damage due to mice?
Can be hellacious locating damaged line(s) since it's a random location unlike known/documented chafe points.
Evidence of chewing @ harnesses etc are obvious tells, pray it isn't under dash.
But if inside a nest somewhere is in play, also.
Been down this road twice, living in the country.

Here's to hoping something electronic failed & not rodent damage.

Bruze

Long story, but almost no chance of mice damage. Thanks anyway!

BadAV

Maybe check the main connections under the passenger footwell and make sure they are firmly seated. That's at least a start and easy to do.

LMB-Z

I bet the blinker fluid needs changing...just saying Hope you get it figured out soon and cheap.

WW7

Bruze, do you know anyone with a Tech 2 unit, it may help isolate the problem farther.. With a Tech 2 you can run scans on different areas to help narrow the problem down.Also may want to erase the codes and see if they come back, they may not..... WW
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jrose7004

And you might start it today and the check engine light will be off and never to return.

Bruze

That will be on the list if the easier stuff doesn't work.

Thanks. My out-of-town buddy has a pretty good one (runs a repair/body shop) but I don't know any more than that right now.

I'm pretty clueless about modern cars and scan tools. The manual with mine said to be careful about erasing codes, something about "Freeze Frames," and "manufacturer specific data," none of which means anything to me. Is there a real reason why I should not erase them and see if they come back? I originally bought this because I had tranny problems with a 2011 truck I had, and I do remember erasing codes with no ill effects. But the electronics in this car scares the crap out of me.

Weather will suck again tomorrow but nice on Thursday. I'll drive it to lunch then and see.

Not sure if this helps with diagnosing or not, but FWIW: Sunday I drove about 25 miles, made two stops a short distance apart, then drove 35 or so miles back to the local "watering hole." When I left there is when the light came on and no, I wasn't drunk, no burnouts, no wild women distractions.

nick14003

Check battery voltage first, then check all fuses in both boxes, pull out and reinsert a few specific ones that are related to the modules to check for corrosion causing a bad connection.

Have you done anything to the car recently, changed any part, replaced anything, installed anything, got anything wet, or had anyone work on it? If so that could help point you in the right direction.

Finally, you can clear codes without causing any issues, just remember to record all the codes before erasing and see if they come back. You might get lucky.

JoeMatilda

Bruze

Where are the fuse boxes? No changes to the car at all, nobody's touched it, hasn't been in rain since 2015 or maybe '16, lol. Had I made any recent changes, that would be my first suspicion.

Okay on clearing the codes. For four years now I know I've been running on fumes, I knew at some point an electronic problem like this would pop up that I knew nothing about fixing or diagnosing.

A guy a few miles down the road is an old gearhead (my age) and he's got an old ratrod in front for sale. It's a '30s-something, just primered. Every time I drive by it it tempts me -- at least I know how to fix it.

crusher1

Control Module Communications Bus Off is code U0073....It may be the connectors under the passenger foot well. could be loose...Take a look and re-seat them. You can erase the code with no issues with a scanner. See if it comes back