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Discussion Starter · #1 ·
I have a 2015 TRAX LS 1.4L with 115K miles. I am the original owner and know the complete service history of the vehicle. A few weeks ago I drove to the supermarket and when I started the car back up the check engine light immediately came on. I pulled a single code - "U0073 Control Module Communication Bus Off." I cleared the code and did not start or drive or for a few days. The next time I drove it, I let it warm up and went less than a mile before the check engine light came on. Another 1/2 mile and every warning light on the dash came on. The tach stopped working, the car lost power, dropped to low gear, and speed was restricted. Less and another 1/2 mile and everything went back to normal (except for the check engine light). I cleared the code, checked all the fuses, and reseated the harnesses on the computer. The next time I drove it, the car started right up and was fine for about 5 miles before the same condition repeated. The battery is less than 6 months old and is testing a full voltage. The original alternator is charging at least 14.5V as tested at the battery.

I am reluctant to drive the car at all because I am afraid of getting stuck. I suspect the TIPM may be the problem but I'd like to feel more confident about replacing it before I spend the time and money. Has anyone had similar symptoms or experiences with their TRAX? Does anyone have any suggestions to troubleshoot this further?

Today I started it (did not drive it) and there was no check engine light. However, I checked for trouble codes and 3 popped up. I cleared them and rescanned with no codes. Photos are attached. (P0700, U0100, U0073.)

Any advice? Thanks.
 

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Sure looks like a bad ground. Check the one in front of the battery at the bottom.

 
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Discussion Starter · #3 ·
Thank you for the tip. I checked that ground connection and it wasn't loose, but it had a lot of oxidation. Cleaned it off and reattached. Car runs great and no more trouble codes. You saved me a lot of time, money, and headaches.
 

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You're welcome!
 
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I been reading all your responses on these codes and checked the grounds, all clean sadly! Quite frustrating, I have a appointment but not for a week in a half, dam Covid wiped the shop out! What’s your next idea?

Sure looks like a bad ground. Check the one in front of the battery at the bottom.

 

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What are your symptoms and codes if any?
 

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Same codes as above, starts with service traction control, then stabilitrack, rpm and speed gauges flutter, speedometer jumps down to zero then back up, loss in power steering, and rougher shifting. Found a tsb on these codes but I don’t see any wiring issues

QUOTE="Traxy, post: 72772, member: 11410"]
What are your symptoms and codes if any?
[/QUOTE]
 

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This is a bad ground if not the usual suspect in front of battery it may be chewed or broken upstream to all these sensors. They can't all go bad at the same time so it has to be something common. Either ground or possibly a corroded fuse supplying the regulated supply to these sensors.
 
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I’ve yet to check the lil 10a fuse you posted (not setting all the way in) in a different thread it’s my next step, spent the evening reading all your post lol and running looking at your suggestions then looking for the TSB’s wire issue
 

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Don't believe everything you read, I've been corrected a few times.

 

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I’ll take that, but still you’re all over these types of post and for some folks it seems spot on so I’ll check your ideas still lol but in the end I have a dealer appointment the 22nd and still under powertrain warranty for 9k more miles lol so I’ll park it till then and hope it’s something free haha
 

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Thanks for the vote of confidence.
 
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Thanks for the vote of confidence.
Regarding our conversation, the fucking ECM needed an update which of course wasn’t covered under the powertrain warranty but atleast it’s back up and running normally till the next fucking update I suppose! Thanks for your knowledge on future issues though!
 
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