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acm 1312 high side temperature short circuit


joshpb

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I have a 1999 cadillac deville. Just figured out how to use the OBD. current code is acm 1312. I've read in different forums it could be the sensor or wiring. Where is the sensor? I've changed the coolant temp sensor?? Any help or ideas? If you do please bare with me im fairly new to mechanical lingo. 

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The high side temp sensor or thermistor is located on the AC line that runs along the firewall toward the brake booster.  It is item #3 in the diagram below.

AC diagram.jpg

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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Unplug the sensor, then turn the ignition to ON and enter diagnostics.  If the code changes to the "High side temp. open, then the sensor is bad.  You will need to recover the refrigerant in order to change the sensor.  Don't just unscrew it or you'll have a massive refrigerant leak.

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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Does the 1312 code say current or history?  I would clear the codes, then run the ac and see what code shows up.  If it is the same code if the sensor is plugged in or not, then it sounds like a wiring issue, and you need to look for damaged wires, or corrosion in the connectors, etc. 

 

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With the sensor unplugged, clear the codes, then re-enter diagnostics.  If the shorted code is still current, then there is a short in the wiring to the sensor.

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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Does that mean I have to replace the whole wiring?? Because i did just what was told. Disconnected the wire from sensor. And ran diagnostic again. Yes the code is still current. Any videos or play by play of how to replace the wiring?

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Trying to find more data on this, and realising they're connected, like i said Im new to this mechanical stuff. Awhile ago, the screen was saying low on ac Freon. But just as fast as it came on, it went away. Could giving it more freon help here? I apologize in advance if i should have started with that. 

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1 hour ago, joshpb said:

Does that mean I have to replace the whole wiring?? Because i did just what was told. Disconnected the wire from sensor. And ran diagnostic again. Yes the code is still current. Any videos or play by play of how to replace the wiring?

Since the code is still current with the wiring disconnected, that means the two wires that connect to the sensor are shorted somewhere.  Visually inspect the wires for chafing as far back into the main harness as far as you can.  The plug could also be damaged,

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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10 hours ago, joshpb said:

What is the actual name for the sensor? So i can find the connection/plug. Any help as to when/if i find problems along the wires? 

Per the diagram I posted, it is #3 - High Side Thermistor.  I am confused - you state you're looking for the plug?  I thought you unplugged the sensor and re-ran diagnostics?

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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Ivd been looking that up and havent been able to find a place that sales a thermistor. I apologize. Im not looking for the location of the plug on the vehicle itself. I meant to look for a place that sales the part. Incase thats a problem i know where to purchase another. I should have been more specific. 

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Did u try www.rockauto.com

?

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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9 hours ago, joshpb said:

Ivd been looking that up and havent been able to find a place that sales a thermistor. I apologize. Im not looking for the location of the plug on the vehicle itself. I meant to look for a place that sales the part. Incase thats a problem i know where to purchase another. I should have been more specific. 

I just looked up the ACM 1312 code up in the shop manual - that is the code for the high side temp sensor OPEN CIRCUIT, not shorted.  If the ACM 1312 code is set with the sensor plugged in and unplugged, it would appear that the sensor is opened.  Unplug the sensor and jumper the pins on the harness, then enter diagnostics.  Does the ACM 1312 code turn to history and is ACM 1313 now set (the shorted code)?  If so, the issue is the sensor since you simulated a shorted sensor by jumping the pins on the harness.

You will need to have the refrigerant recovered in order to replace the sensor as there is not a Schrader valve in the fitting?

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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Woow.. Im sorry for the misinformation. I just have a way bigger problem now.. Thank you KHE for all the advice it is highly appreciated! But now my car will not start at all. I believe it is bc of the VATs? It does not click over. I try but only get a ticking noise coming from the fuse box under the hood. The security light is flashing on the dash. Most weirdest part of it all is i try to plug a scanner and  the car is making the scanner malfunction. When the car starts ticking the scanner starts flashing. Before the scanner went crazy it did say low battery voltage. When we used a multimeter on the battery it showed it was pumpin 11 volts. Is that good or bad? And before any1 says anything. I did make a new thread about this. But received no replies. Yet..

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Check connections at the battery for corrosion and tightness, have the battery load tested to be sure its good.  It sounds like your battery is toast.

You need to check codes, and report them here with all DIC messages.  The only way to make sure that its VATS is via codes.   Codes are your best friend.  Your car will give you BODY and CHASSIS codes which will give us more info as to what the problem might be.

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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Okay back on this thread! Bobby you were correct about it being the battery! Many thanks for that! I thought it was something waay worse. Buut once i ran the on board diagnostics. And like originally, acm 1312. High side temp OPEN circuit, as i know now is tje correct meaning for the code thanks to KHE. And PCM 1660 cooling fan control circuit. KHE, can you explain to me the play by play of how to what you were saying? I am already low on refrigerant as the car is saying. And are there any suggestions for the PCM code?? I know im asking alot for free help but its highly appreciated! 

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25 minutes ago, joshpb said:

Okay back on this thread! Bobby you were correct about it being the battery! Many thanks for that! I thought it was something waay worse. Buut once i ran the on board diagnostics. And like originally, acm 1312. High side temp OPEN circuit, as i know now is tje correct meaning for the code thanks to KHE. And PCM 1660 cooling fan control circuit. KHE, can you explain to me the play by play of how to what you were saying? I am already low on refrigerant as the car is saying. And are there any suggestions for the PCM code?? I know im asking alot for free help but its highly appreciated! 

Read my last post - I described the steps on how to verify that the sensor is bad.  The last thing you want to do is go through all the trouble of replacing the sensor and not have the sensor be the problem.

Once you verify the sensor is the problem, you will need to have the refrigerant recovered in order to change the sensor but before doing that, you will need to have the system checked for leaks, recover the refrigerant, repair any leaks so the new charge of refrigerant does not leak out, then have the system evacuated and charged with 2.0 lbs. of R-134a.

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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2 minutes ago, joshpb said:

When i remove the sensor will refrigerant come out? I will do what you said to check the sensor but the rest seems like something i should take to the shop to do. Thank you KHE. 

Yes, as KHE mentioned you need to take it to a shop to depressurize and collect the Freon, so you can change the sensor, and then recharge it after its changed. 

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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