U1301 - ECTS Related?

[nivlem7]

U1301 - Class 2 Short to Battery

Had this code a few months back, replaced the ECTS and it hasn't returned. Anyone know what it means (other than a short to the battery ) and if it's related? I haven't found any info that would connect the two.

edit: I believe class 2 is the designation for GM's DTC communications.

[DonP]

My impression is that U1301 relates to a failure of internal communications between the various diagnostic and control modules (e.g., microprocessors/computers ) in the car. Almost sounds as if for some reason the data link was pulled high, possibly by an intermittent short.

A bad ECTS appears to mess with just about everything else in the car, why not communications although I fail to see a clear connection (no pun intended).

[nivlem7]

Originally Posted by DonP

A bad ECTS appears to mess with just about everything else in the car, why not communications

Indeed!

[nivlem7]

Interesting link on Trouble Code diagnostics.

http://www.gmtcny.com/serial%20data.html

[Phredawgy]

Originally Posted by nivlem7

Interesting link on Trouble Code diagnostics.

http://www.gmtcny.com/serial%20data.html

Check this one out too
http://www.regalgs.org/obd2.htm
If you can read that chart without getting dizzy it might help

[Phredawgy]

Or if you use the chart on this cadillac site(which looks to be put together in an understandable manner and is the same as the other link) it might give you a better clue



http://myweb.accessus.net/~090/dtcobd2m.html#man
so if I am reading this right
U=Network code
1=Manufacturer Code
3=Ignition System Or Misfire
01=General Sensor Fault

[nivlem7]

That would make sense to me, as far as pointing to the ECTS.

The Cadillac link also mentions the the code : DTC 14 - Coolant Temp Voltage Low which would be U1314, I believe. I didn't know that the ECTS had any specific codes, and am surprised that I didn't see that one.

Thanks for the links!

[Phredawgy]

Originally Posted by nivlem7

That would make sense to me, as far as pointing to the ECTS.

The Cadillac link also mentions the the code : DTC 14 - Coolant Temp Voltage Low which would be U1314, I believe. I didn't know that the ECTS had any specific codes, and am surprised that I didn't see that one.

Thanks for the links!

Yeah.....either that or didn't you have an cylinder misfire code when this first showed up.....it could have been just stuck in the memory...but the ECTS can cause wierd idle and on occasion misfire problems for various reasons

[nivlem7]

Originally Posted by Phredawgy

Yeah.....either that or didn't you have an cylinder misfire code when this first showed up...

Actually, I did have the cyl 1 misfire code originally (P0301, IIRC), along with the U1301. Had the IMG replaced, which eliminated the misfire code, but the U1301 kept coming back, until I replaced the ECTS.

Originally Posted by Phredawgy

.....it could have been just stuck in the memory..

So would you say it's rather inconclusive as to whether or not the ECTS was the cause of that code?

[Phredawgy]

Originally Posted by nivlem7

Actually, I did have the cyl 1 misfire code originally (P0301, IIRC), along with the U1301. Had the IMG replaced, which eliminated the misfire code, but the U1301 kept coming back, until I replaced the ECTS.




So would you say it's rather inconclusive as to whether or not the ECTS was the cause of that code?

No, If it was in the history it would have said so...and since ECTS issues can cause a misfire that could have been your problem

[nivlem7]

They're baaaack.

Yesterday, my mom borrowed my car and drove about 150 miles round trip. This morning, I noticed the SES light was on, and she said it illuminated about 25 miles before she got home. The code went away after about 10 minutes of me driving. I scanned the codes and got the two that I haven't seen since I replaced the ECTS 4 and 1/2 months ago:

P0172 - System Too Rich
U1301 - Class 2 Short to Battery - this one is a "pending" code.

Freeze frame data from the scanner says:

Calc Load (%) = 58.4
Coolant (deg F) = 185
ST FRM1(%) = - 1.5 (yes, it's a negative)
LT FRM1(%) = - 21.8 (again, negative)
MAP (in. hg) = 20.4
ENGINE(RPM) = 2177
VEH SPEED (MPH) = 21
ABSLT TPS(%) = 14.1
Second Air = ERROR

All applicable I/M status' are ok

Can anyone tell me what the ST FRM1 and LT FRM1 are?

Also, is it possible that the PCM "learned" my style of driving, and created a too rich mixture based on my mom's driving?

Also, could it be related to a blown parking lamp fuse a few days ago?

This is driving me nuts.

[fdryer]

When you replaced the ECTS did you check the two-wire connector for any signs of corrosion from leaking coolant? The corrosion may act to restrict voltage, basically doing the same as if the coolant sensor wasn't replaced and still causing a rich running condition. The rich running condition is shown as the short and long term fuel trims as negative values. The short term trims are for everyday driving and skew the overall a/f ratios while the long term trims are based on the average short term trims. Does the engine idle higher than 800-900 rpm when fully earmed up? Is the thermostat operating at temperature and not below? An open thermostat or leaking O-ring from the thermostat housing may allow the engine to run cooler than normal and the coolant sensor may detect this, informing the PCM as an engine not up to operating temperatures and continue running it rich as reflected by the trim percentages. Negative numbers indicate rich a/f mixtures while positive numbers reflect lean conditions. Plus or minus 8% would be considered normal, so the minus 21% is way over and probably set off the P0172 code. Just my 2-cents.

ST FRM1(%) = - 1.5 (yes, it's a negative)
LT FRM1(%) = - 21.8 (again, negative)

Some light reading; http://www.aa1car.com/library/2004/cm100428.htm and http://www.lt1howto.com/articles/pcmtuning.htm may give you some more information to help understand what's going on.