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Master Auto Tech.
Master Auto Tech., A.S.E. Certified Master Technician
Category: Chevy
Satisfied Customers: 465
Experience:  Over 20 years working on imports and domestic cars
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2013 silverado no com between modules

Customer Question

2013 silverado no com between modules
Submitted: 9 months ago.
Category: Chevy
Customer: replied 9 months ago.
at differnt times was able to pull codes u0073 u0100 u0121 u0140 abs u0100 u0140 u0137 then at times no comunication have power and ground at abs check 3 spot for body grounds all fuses good when it happens dash will shut down also
Customer: replied 9 months ago.
also vehicle looses power and then wont start for awhile no comunication to ecm trailer brake abs trans instrument steering stability bcmwiggiled wires made no differnce
Customer: replied 9 months ago.
problem started all of a sudden attempted to clear codes when i was able to comunicate but naturaly reappeared
Customer: replied 9 months ago.
i know nobody wants to get involved with this one am i right
Expert:  CHRIS ZAPANTIS replied 9 months ago.

Ill give it a shot

Expert:  CHRIS ZAPANTIS replied 9 months ago.

Did you look at the connector for the trans? They sometimes chaffe while rubbing against the trans.

Expert:  CHRIS ZAPANTIS replied 9 months ago.

Im Chris by the way.

Expert:  CHRIS ZAPANTIS replied 9 months ago.

Put that thing up in the air and look at the connector.

Expert:  CHRIS ZAPANTIS replied 9 months ago.

Check for chaffing and pins pulling out.

Expert:  CHRIS ZAPANTIS replied 9 months ago.

This is a common place they get damaged on the side of the trans.

Expert:  CHRIS ZAPANTIS replied 9 months ago.

this is an example of pins pulled out.

Expert:  CHRIS ZAPANTIS replied 9 months ago.

Let me know.

Expert:  CHRIS ZAPANTIS replied 9 months ago.

Did I lose you?

Customer: replied 9 months ago.
looked at connections found no pins pulled and no corosion trans abs ecm and trailer brake
Expert:  CHRIS ZAPANTIS replied 9 months ago.

Did you check the wires by the side of the trans for chaffing?

Customer: replied 9 months ago.
followed wires from trans along frame found no problem
Expert:  CHRIS ZAPANTIS replied 9 months ago.

What bothers me is that you can communicate at times. Its not constant. There has to be a wiring issue here.

Expert:  CHRIS ZAPANTIS replied 9 months ago.

give me a minute.

Expert:  CHRIS ZAPANTIS replied 9 months ago.

The connector at trans is round right?

Expert:  CHRIS ZAPANTIS replied 9 months ago.

left fron frame rail is another common rubbing point. Rubs against brake line.

Expert:  CHRIS ZAPANTIS replied 9 months ago.

Also look under dash wiggle all wire harnesses to side fuse box and by break pedal they have at least to different places where rubbing has occured.

Customer: replied 9 months ago.
trans plug is round
Customer: replied 9 months ago.
alteady did do the wiggle under dash the brake pedal is stationary so nothing was moving to wear wiggled and nothing changed
Expert:  CHRIS ZAPANTIS replied 9 months ago.

have you seen this bulletin?

Customer: replied 9 months ago.
my thought something with can bus wiring???
Expert:  CHRIS ZAPANTIS replied 9 months ago.

yes but where are they damaged?

Expert:  CHRIS ZAPANTIS replied 9 months ago.

Look at that bulletin it can be anywhere.

Expert:  CHRIS ZAPANTIS replied 9 months ago.

it can be a loss of power or ground also

Expert:  CHRIS ZAPANTIS replied 9 months ago.

Somewhere in the harness.

Customer: replied 9 months ago.
i sort of knew this but was hoping for some type of direction to isolate
Expert:  CHRIS ZAPANTIS replied 9 months ago.

I hear you.

Customer: replied 9 months ago.
my understanding it could even be a module but dont how to isolate to take out of equation
Expert:  CHRIS ZAPANTIS replied 9 months ago.

What bothers me is that its intermittent

Expert:  CHRIS ZAPANTIS replied 9 months ago.

Usually when a module goes bad its bad.

Expert:  CHRIS ZAPANTIS replied 9 months ago.

can you do a complete system scan? What kind of scanner do you have?

Customer: replied 9 months ago.
a autel and geynisis
Expert:  CHRIS ZAPANTIS replied 9 months ago.

if you scan it right now tell me the codes

Customer: replied 9 months ago.
which system do you want scanned
Customer: replied 9 months ago.
ecm or trans or abs or trailer brake or bcm or instument
Expert:  CHRIS ZAPANTIS replied 9 months ago.

it wont scan complete car?

Expert:  CHRIS ZAPANTIS replied 9 months ago.

scan ecm

Customer: replied 9 months ago.
had cleared codes early in day and only ran on jack since codes came up p0700 p2544 p0575 p1506 u0073
Expert:  CHRIS ZAPANTIS replied 9 months ago.

ok gimme a minute

Expert:  CHRIS ZAPANTIS replied 9 months ago.

let me check those meanwhile scan tcm.

Customer: replied 9 months ago.
tcm unable to comunicate bcm unable to comunicate abs unable to comunicate trailer brake unable to comunicate instrument no problem found no codes
Expert:  CHRIS ZAPANTIS replied 9 months ago.

can i get the eigth digit of the vin?

Expert:  CHRIS ZAPANTIS replied 9 months ago.

so basically you can communicate only with ecm.

Customer: replied 9 months ago.
g
Customer: replied 9 months ago.
at this time but have been able to comunicate with the others at differnt times though out the day
Customer: replied 9 months ago.
never was able to get trailer brake
Expert:  CHRIS ZAPANTIS replied 9 months ago.

it does start though correct

Customer: replied 9 months ago.
it does it was towed in would only go about 10mph then quit would not resrsrt i got it after being towed started up everytime
Expert:  CHRIS ZAPANTIS replied 9 months ago.

So youre a professional? I would start by diagnosing U0073.

Expert:  CHRIS ZAPANTIS replied 9 months ago.

Do you have alldata or mitchell?

Customer: replied 9 months ago.
just a friend helping out and no alldata or mitchell
Expert:  CHRIS ZAPANTIS replied 9 months ago.

ok if its ok with you I will opt out because I get up in 6 hours. I cant help you till tomorrow night. If you want I can go through the checks with you then, or i can opt out so you can get help in the daytime. Let me know.

Customer: replied 9 months ago.
would like to try first thing in morning with someone if possible
Expert:  CHRIS ZAPANTIS replied 9 months ago.

ok no problem I will opt out so you can do so. Good luck!

Customer: replied 9 months ago.
is anybody out there to help
Expert:  Master Auto Tech. replied 9 months ago.

I'm sorry you are having problems with your vehicle. I will try to help.

I'm a full time mechanic and have been a mechanic for over 20 yrs and I work part-time here on JustAnswer to help you and others repair their own vehicles, and I get credited by your ratings.. So before leaving the site make sure and leave me a rating. You can still reply to me as many times as neeed, even after the rating.. I will need for you to be my hands and eyes since I'm not there.

ok I will give it a stab. I just read your replys. So start by unplugging modules and as you do rescan the pickup. When the other modules are readable start plugging the rest in but leave the one unplugged and see if they will all be readable with that one unplugged. let me know what you find. Thanks Sonny

Customer: replied 9 months ago.
well that absolutly confussed me unplugged abs scanner still on ecm unplugged trailer same unplugged trans no more comunication to ecm pluugged abs in nothing trailer nothing trans in ecm comunicated code u0121 p0575 p0700 p150c p2544 u0073 u0101 u0121 u0140 tcans codes p0121 abs codes c0110 u0100
Expert:  Master Auto Tech. replied 9 months ago.

just for kicks try unplugging the ecm and then scanning the rest of the systems.

Customer: replied 9 months ago.
did you give up or quit
Expert:  Master Auto Tech. replied 9 months ago.
I'm sorry, I was waiting for a reply to the last thing I sent.
I asked if you would mind unplugging the ecm and checking the rest of the system with it unplugged.
It shows it went thru but maybe it didn't.
Expert:  Master Auto Tech. replied 9 months ago.
Also with the GENISYS you can do a complete system scan not just ecm. So ea time you unplug modules it would be good to scan everything. Not just the ecm. That way you can see what is killing the can bus line.
Also was there any work done on the vehicle recently?
Expert:  Master Auto Tech. replied 9 months ago.
Well I have to sign off for the day. I'll opt out and see if the other guy can help in the mean time.
Customer: replied 9 months ago.
is there anybody going to respond or am i on my own someone let me know please so i can do something
Expert:  Master Auto Tech. replied 9 months ago.
Ok so I'm back on for the day, I apologize, I have a weird work schedule so I sign off early and back on early. I will try to help some more but not completely sure if I can help you fix it or not with out being there so please be patient with me.
So here we go, if you can, try disconnecting the ecm and scanning the other modules and see what happens.
Also check for any chafed wires down by the emergency brake. Look very closely and carefully
Expert:  Master Auto Tech. replied 9 months ago.
Are you still wanting help?
Customer: replied 9 months ago.
just not lining up on scheduje juct took truck to dealer
Expert:  Master Auto Tech. replied 9 months ago.
Ok no problem. Would you mind posting what they find? I'm curious to see what it is.Thanks
Sonny