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2000 Seville SLS
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3 Posts
Discussion Starter #1
well i pulled a new DTC from the caddy today
U1016 (history) - Loss of Communications with PCM

being a history code and nothing actually occurring at this time to make me think there is something wrong (runs, drives, functions perfectly) i'd assume this was just a hiccup in the system somewhere, but figured i'd ask anyway.

i also have a code for the evap system (the seal between the filler neck and tank has gone bad), and a code for the front brake sensors (mom drove it for too long with won out pads and destroyed them) but those have been around forever by now lol.

any ideas what may cause this code to set?
 

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2001 Seville SLS
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444 Posts
The U1016 code is commonly caused by the PCM not receiving enough power at a moment in time. Without adequate power it cannot send a signal. Technically, the module that sent the trouble code, indicated by the three letters in front ot the U1016 code, did not receive an expected signal from module 016, the PCM.

It is a good idea to jot down all of the codes that are sent including the three letters in front of the codes and the list of all of the modules that send no codes on your car. That way you will be able to compare it to the list the car will send when there actually is a problem with a module. A troubled module does not send a code and will be missing from the list.

You can make your mom's day by fixing the brake indicator. It is a simple job to solder the wire back together and wrap it with a little electric tape. It is a ground wire and the warning light comes out when the circuit is no longer grounded. She will think you are a genius.
 

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99 STS, White Diamond
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792 Posts
"Hiccough" is a good way to describe an occasional "Loss of communications U-code". A great number of electronic modules are all linked via one-wire, rather like having a dozen USB devices connected to your computer. All constantly report their state-of-health to the PCM (power control module) and on occasion and even in a perfectly functioning car something can miss a couple beats.
 

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2001 Seville SLS
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444 Posts
In a perfectly operating car, there are no hiccups, codes, and the car doesn't blow wind. You can fix the car so that no codes show up ... until something else goes wrong.

The car will 'function' just fine with most errant codes and most people ignore them. The effort required to eliminate history codes is not always worth the benefit.
 
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