Topic: U0073

[Arabas]

I took the gt today and when i started the engine i got a Cel and a car/lock symbol on the dashboard. Car was working great. Checked ug and it showed u0073 Control module communication Bus off.
After 60 miles driving i made a stop at the grocery shop and when started the car the cel and car lock icon had disappeared.

What i did different this time is that i connected the ug before i turned the key to position on.
Could that be it? Or maybe my 5+ yrs old battery playing games?

Btw, car runs great and absolutely no problem starting


Any opinions?
Scanner r u here buddy?

[DeepBlueGXP]

Gotta be the battery

sent from my android phone using Tapatalk 2

[Arabas]

Have u heard of these symptoms before Joe? Funny think is that it crancked normally and voltage during cruising seemed ok

[elff]

Our batteries kind of just off a cliff at the 5 year mark.
Lots of examples of that.  I agree with Joe, sounds like another weird electrical issue caused by a failing battery

[1LILNDN]

I've only had the Lock out code 1 time when I was trying to connect a different ECM . My battery shorted out after only 2 years .

[Carbon Sky]

I'm curious, do they sell AC Delco batteries out there?  Or are their European brands out there that we don't have here?

[tazz]

Grounding issue?
I thought there was a PI Bulletin on the issue for some GM vehicles.

[tazz]

Service Information
2009 Chevrolet Cobalt | Cobalt, G5 (VIN A) Service Manual | Preliminary Information | Document ID: 2470794
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#PIC5350: Intermittent IPC Gauges WOW Multiple warning Lights On May Or May Not Have Codes P0575 U0140 U0121 U0073 P0703 Set - keywords ABS boost cluster communication DTC gage gauge inop inoperative IP light - (May 12, 2010)


Subject: Intermittent IPC Gauges WOW, Multiple Warning Lights On, May Or May Not Have Codes P0575 U0140 U0121 U0073 P0703 Set


Models: 2009 - 2010 Chevrolet Cobalt W/UAF Configurable DIC




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The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

Condition/Concern:
Some customers may comment that the IPC gauges WOW and/or multiple warning lights are illuminated. Upon inspection technician may find DTC's P0575 U0140 U0121 U0073 P0703 stored.

This may be caused by a pinched harness between the I/P carrier and body mount.

Recommendation/Instructions:
Remove IPC & instrument panel cover to gain access to the configurable DIC harness. Inspect harness 14 inches from display at the IP carrier mount on left side of dash for pinched wiring - See attached photos.








See SI Document ID: 1378906 for approved GMLAN wiring repairs.

Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.

GM bulletins are intended for use by professional technicians, NOT a "do-it-yourselfer". They are written to inform these technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions, and know-how to do a job properly and safely. If a condition is described, DO NOT assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See your GM dealer for information on whether your vehicle may benefit from the information.

[tazz]

U0073 - Definition: Control Module Communication Bus "A" Off
U0140 - Definition: Lost Communication With Body Control Module

What needs to happen is the cluster can be commanded to sweep gages using the GM Tech 2 scan tool. Keep in mind that the gage testing and any programming needs to be done at a GM dealer using the GM Tech 2 scan tool. If they respond correctly to that command that means the gages and wiring to the gages is fine and the part(s) responsible for sending info to the gage is inaccurate. If they don't sweep ok then suspect a faulty cluster. To do the sweep test it needs to go to a GM dealer though. The gages not being accurate is common on the older year trucks and a cluster is the fix (along with programming the new cluster using GM software).

Check this information about #PIT4730: Additional Diagnostic Information For U0140 Or U0073 - keywords BCM comm communication cycle DIC door freeze gage gauge inop inoperative int intermittent LAN locks message no service speed speedo - (Oct 3, 2008)

Subject: Additional diagnostic information for U0140 or U0073

Models: 2008-2009 Buick Enclave
2006-2009 Buick Lucerne
2006-2009 Cadillac DTS
2007-2009 Cadillac SRX
2008-2009 Cadillac CTS
2007-2009 Chevrolet Avalanche, Silverado, Suburban, Tahoe
2006-2009 Chevy Impala
2006-2007 Chevy Monte Carlo
2008-2009 Chevy Savana
2007-2009 GMC Acadia, Sierra, Sierra Denali, Yukon, Yukon Denali, Yukon XL, Yukon Denali XL
2008-2009 Hummer H2
2008-2009 Pontiac G8
2007-2009 Pontiac Torrent
2007-2009 Saturn Outlook, Vue

The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

Condition/Concern: Some customers may complain of one of the following symptoms:
• Door locks cycle while driving
• Intermittent No Start
• Service Stabilitrak DIC message
• Speedometer and tachometer freeze while driving

Along with these complaints DTC U0140 00 and/or U0073 71 may be stored as a history code in any GM LAN High Speed module.

If the data circuits (2500 & 2501) have experienced an "intermittent" short to ground or short to each other "2 times" within a period of less than 1 second and then go back to normal, the BCM may appear to be "off-line" on the high speed buss. This intermittent scenario should not cause other modules to lose communication, only the BCM. If this situation happens, the BCM will not start communicating with other modules again until the key is out of the ignition and the BCM has timed out (approximately 20 minutes).

Typically the customers complaint will be intermittent and usually occur when driving over bumps/rough roads.

Recommendation/Instructions:
If DTC U0140 00 or U0073 71 is set only as a HISTORY code in any of the high speed modules, refer to "Testing for Electrical Intermittents" in the service manual to reset the DTC and diagnose the location of the fault.

Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.


Also coudl visit your delaer and ask fot this Bulletin:
TSB Number: 08-07-30-021 NHTSA Number: 10025402 TSB Date: April 1, 2008 Date Added to File: August 6, 2008
Failing Component: Engine And Engine Cooling:Engine
Summary: Loss of high speed gmlan communications, intermittent no crank, ipc gauge fluctuation, intermittent door lock cycling, transmission may not shift, DTCs U0073, U0100, U0101, U0102, U0140 (repair backed out terminal in transmission harness connections).

[Arabas]

I'm curious, do they sell AC Delco batteries out there?  Or are their European brands out there that we don't have here?

Yeap we have ac delco around here. Bosch though is the most common a brand. We also got a whole lot other a and b brand options