OynxSTS Posted May 28, 2010 Report Share Posted May 28, 2010 So yesterday I take the 2002 STS into the dealer to have a keyfob programmed that I scored on ebay for next to nothing... All went well Fob programmed without any fuss while I waited... The car returns and now it is issuing a B1321 code that I can't clear and the A/C system is off line. dead. So after a short bit of reading (and my handy dandy eSi system) I discover that this is an low temperature sensor out of range... From the service manual... "When the refrigerant is cold, the sensor resistance and signal voltage are high. When the refrigerant is warm, the sensor resistance and signal voltage are low" Also per the service manual they recommend that you first check for a correct signal voltage... I measure across the pins of the connector and I get a near perfect 4.99 volts. After a little bit of investigation I was lead to believe that you could "test" and "trick" this circuit with a 4K-8K resistor and basically prove that the thermistor is bad. So I stick in a 4.7K ohm resistor and... Still dead.. hmmm... Does anyone know what resistor I should try on a 2002 STS to "fake" this switch? I know that this switch is common to almost all NorthStar cars... And I know that others have reported success with the 4K ohm trick. Any thoughts? My conspiracy question is: Is there anyway that the dealer could have "forced a code" into the A/C system to force a return visit? My wife thinks it is way too coincidental that right after the Fob gets programmed the A/C is dead.... Where does the programing for the Key Fob live in the DIM (Dash integrated module)? Is there a chance that the tech made a mistake and changed a setting on my A/C system? As always thanks for your help guys. Easin' down the highway in a new Cadillac, I had a fine fox in front, I had three more in the back ZZTOP, I'm Bad I'm Nationwide Greg Link to comment Share on other sites More sharing options...
BodybyFisher Posted May 28, 2010 Report Share Posted May 28, 2010 This is interesting. Suprisingly the SI does not speak to diagnosing the sensor by substituting a resistor. Maybe its possible that your resistor value is off. They did say this also Inspect for poor connections at the harness connector of the dash integration module. There seem to be two dash intergration modules... I wonder if the key fob interacts with the dash integration module? 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 Link to comment Share on other sites More sharing options...
OynxSTS Posted May 28, 2010 Author Report Share Posted May 28, 2010 I don't know... But it is really weird... A quick back probe of the A/C switch/sensor yields a 3.2K Ohm reading (which is right in spec for ambient temperatures) I stick the 4.7K Ohm resistor back in the conector and I measure the voltage drop across the resistor and it gives me a 1.7V... Again, right in the range you would expect... AND the range that the DIM computer should be happy with (at least it should be as per the Service manual) A little ohms law and I get that the sensor (at ambient temperature) would yeild a voltage signal of 1.15V which is well within the values that the car should be happy with.... I think I smell a rat. Easin' down the highway in a new Cadillac, I had a fine fox in front, I had three more in the back ZZTOP, I'm Bad I'm Nationwide Greg Link to comment Share on other sites More sharing options...
BodybyFisher Posted May 28, 2010 Report Share Posted May 28, 2010 I trust you have disconnected the battery? I wonder if false codes can be locked into the PCM?, I would be surprised What about the DIMs?, if they unplugged something? Did you find the DIM in the SI? 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 Link to comment Share on other sites More sharing options...
OynxSTS Posted May 28, 2010 Author Report Share Posted May 28, 2010 I trust you have disconnected the battery? Great minds think alike, I just got off the phone to a trusted mechanic... He said that it would be next to impossible for the dealer tech to force a code or a permanent setting on the car... His suggestion, disconnect the battery and let it sit for 20 minutes or so. I'm sceptical, but I'm also desperate. It is resting without power... right now I wonder if false codes can be locked into the PCM?, I would be surprised What about the DIMs?, if they unplugged something? Did you find the DIM in the SI? In theroy there are codes that get locked into the PCM... like Airbag deployment... that can only be reset with a special code from GM HQ... I wonder if A/C is now added to this list? AS far as I can tell the DIM is tucked under the access cover in the passengers foot well... The Fob programming procedure makes no mention of working on the DIM... though it is easy to get to... I will take a look this weekend if the battery "re-boot" doesn't work. They only had the car for 25-30 minutes... I don't think they had time to fiddle with the DIM... but who knows. Easin' down the highway in a new Cadillac, I had a fine fox in front, I had three more in the back ZZTOP, I'm Bad I'm Nationwide Greg Link to comment Share on other sites More sharing options...
Cadillac Jim Posted May 28, 2010 Report Share Posted May 28, 2010 B1321 A/C Low Side Temperature Sensor Fault I would just clean the connector on the sensor and make sure that it was tight and plug it back in, then clear all the codes and see if that does it. See the link in my signature block for instructions on clearing the codes. -- Click Here for CaddyInfo page on "How To" Read Your OBD Codes-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data -- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC Yes, I was Jims_97_ETC before I changed cars. Link to comment Share on other sites More sharing options...
OynxSTS Posted May 28, 2010 Author Report Share Posted May 28, 2010 Have cleaned, plugged and unplug the sensor several times... Cleared the codes even more times... Battery "re boot" also failed... It is interesting that the car's PCM does not perform like the Service manual says it should. The Service manual is very clear, that once it senses this error, it defaults the sensor value to a default value of 5°C (41°F) And that the A/C system should continue to work. But on my car the DIM has forced the A/C "off" Your signature link is broken... needs to be .html not htm Easin' down the highway in a new Cadillac, I had a fine fox in front, I had three more in the back ZZTOP, I'm Bad I'm Nationwide Greg Link to comment Share on other sites More sharing options...
BodybyFisher Posted May 28, 2010 Report Share Posted May 28, 2010 Hmmm, a puzzle, I must look at the wiring diagrams. When you said forced off, do you mean the AC is off, or the AC compressor wont engage? 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 Link to comment Share on other sites More sharing options...
OynxSTS Posted May 28, 2010 Author Report Share Posted May 28, 2010 Hmmm, a puzzle, I must look at the wiring diagrams. When you said forced off, do you mean the AC is off, or the AC compressor wont engage? The compressor won't engage... I can get the blower to blow and the car even tries its best in AUTO mode... but even in "auto mode the A/C pannel reads "A/C OFF" and there is nothing that I can do to turn it on. I will crall under and check the connectors at the DIM. It just seems really odd that I have a good 5V reading at the sensor, I have a good resistance reading at the sensor and when I force a known resistance (that is within a correct and expected range) the computer acts like it is blind to that sensor. No other codes... Weird Easin' down the highway in a new Cadillac, I had a fine fox in front, I had three more in the back ZZTOP, I'm Bad I'm Nationwide Greg Link to comment Share on other sites More sharing options...
BodybyFisher Posted May 28, 2010 Report Share Posted May 28, 2010 For the hell of it, check the connector at the compressor, maybe someone 'accidently' disconnected it, and check the low pressure switch, I know you are not getting a code but just for the hell of it check it, that sensor when engaged or bad, shuts down the compressor from engaging 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 Link to comment Share on other sites More sharing options...
Cadillac Jim Posted May 29, 2010 Report Share Posted May 29, 2010 Thanks for the heads-up about the bad link. It's a bit strange that something like that should crop up. I checked the link when I first stored the signature and I've been using that signature for some time now and never noticed that before. From the behavior of your system it looks like something is setting B1321 other than the sensor itself. My FSM doesn't have a blurb on B1321. Check the details of yours at the beginning of the section and see what the conditions are that set B1321. -- Click Here for CaddyInfo page on "How To" Read Your OBD Codes-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data -- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC Yes, I was Jims_97_ETC before I changed cars. Link to comment Share on other sites More sharing options...
OynxSTS Posted May 29, 2010 Author Report Share Posted May 29, 2010 Thanks for the heads-up about the bad link. It's a bit strange that something like that should crop up. I checked the link when I first stored the signature and I've been using that signature for some time now and never noticed that before. From the behavior of your system it looks like something is setting B1321 other than the sensor itself. My FSM doesn't have a blurb on B1321. Check the details of yours at the beginning of the section and see what the conditions are that set B1321. From my FSM, Conditions for Setting the DTC: The DIM detects the signal circuit is less than 0.09 V or greater than 4.90 V. Which is the confusing part... I have personally verified that with a 4.7K ohm resistor in place instead of the thermistor sensor, the signal circuit was 1.7V right in the "meat" of what the computer is looking for... It should turn off the code. Easin' down the highway in a new Cadillac, I had a fine fox in front, I had three more in the back ZZTOP, I'm Bad I'm Nationwide Greg Link to comment Share on other sites More sharing options...
OynxSTS Posted May 30, 2010 Author Report Share Posted May 30, 2010 Update... Still broken So I crawled underneath the car and unplugged the low pressure sensor to see if that would generate a permanent code too... It immediately triggered a P0532 CURRENT... Plugged it back in and the code became history and was easily cleared. So then I pull the passenger foot well apart to investigate the DIM. Wires all look fine... Unplugged all of the connectors and a quick back probe of A6 and A7 on the blue connector and I can see the temperature sensor (it was now registering 1.8K ohms.. or 0.7V which is still within "Happy computer range"). So the wires are all good. Any other thoughts? So far we have a good sensor, good connectors, good wires, and a voltage signal within correct range... All that I can see that's left is a dead DIM... Just a coincidence that my DIM dies at the same time they program a key fob? Easin' down the highway in a new Cadillac, I had a fine fox in front, I had three more in the back ZZTOP, I'm Bad I'm Nationwide Greg Link to comment Share on other sites More sharing options...
BodybyFisher Posted May 31, 2010 Report Share Posted May 31, 2010 That is odd. Would they swap in a bad DIM? Did you get the code immediately after leaving the dealer? 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 Link to comment Share on other sites More sharing options...
OynxSTS Posted May 31, 2010 Author Report Share Posted May 31, 2010 That is odd. Would they swap in a bad DIM? Did you get the code immediately after leaving the dealer? I don't think its a new/different DIM... I still wonder if they could set some code in it to turn off the A/C Yes, message was displayed immediately after leaving the dealer. Easin' down the highway in a new Cadillac, I had a fine fox in front, I had three more in the back ZZTOP, I'm Bad I'm Nationwide Greg Link to comment Share on other sites More sharing options...
BodybyFisher Posted May 31, 2010 Report Share Posted May 31, 2010 an odd coincidence, I would make a call to them and see if they think they caused it 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 Link to comment Share on other sites More sharing options...
OynxSTS Posted May 31, 2010 Author Report Share Posted May 31, 2010 Talked to dealer, they were adamant that there was nothing that they could do with a Tech II to turn off the AC or permanently set a B1321 code. They were adamant that this was all a odd coincidence and that they would be happy to make an appointment when I would like to have the AC system looked at... grumble grumble grumble... From everything that I can see, it looks like this one function of the DIM just happened to die, at the exact same time that the BCM went into program mode and added a new fob... I hate coincidences like this. At work we have a Snap On Scanner that can reset various GM codes... I will see what that says. Easin' down the highway in a new Cadillac, I had a fine fox in front, I had three more in the back ZZTOP, I'm Bad I'm Nationwide Greg Link to comment Share on other sites More sharing options...
OynxSTS Posted June 1, 2010 Author Report Share Posted June 1, 2010 So the guys at out fleet garage hooked up there scanner to the car... I need to spend some time with that scanner... Not a tech II but it looked just like one... The garage guy knew all about the car and all about Tech II's he was confident that his scanner could program fob and do many things that were "Tech II only" territory. Any who after about 15 minutes with the scanner... he comes back with the bad new... Refrigerant pressure on the low side is 16.8 PSI... (should be about double that)... R134a is a real pain to buy in Canada... Easin' down the highway in a new Cadillac, I had a fine fox in front, I had three more in the back ZZTOP, I'm Bad I'm Nationwide Greg Link to comment Share on other sites More sharing options...
JimD Posted June 1, 2010 Report Share Posted June 1, 2010 ....he comes back with the bad new... Refrigerant pressure on the low side is 16.8 PSI... (should be about double that)... I hope that is your answer. It would at least put the "coincidence" question to rest and might even resolve your A/C situation. R134a is a real pain to buy in Canada... Why is that? Vehicles assembled in Canada (Ontario) for domestic consumption or export to the US have been factory filled with R134 for many years. Jim Drive your car. Use your cell phone. CHOOSE ONE ! Link to comment Share on other sites More sharing options...
OynxSTS Posted June 2, 2010 Author Report Share Posted June 2, 2010 To buy R134a in Canada (at least in BC) you need to be a licensed technician. It is legal to use and to own, just not legal to buy.. (Unless it is aready in a Car, a Fridge, an A/C unit, etc) I'm still investigating if it is legal to import... It is not legal to ship via commercial air. I see a drive to Bellingham in my near future. Easin' down the highway in a new Cadillac, I had a fine fox in front, I had three more in the back ZZTOP, I'm Bad I'm Nationwide Greg Link to comment Share on other sites More sharing options...
Cadillac Jim Posted June 2, 2010 Report Share Posted June 2, 2010 It's not legal to buy Freon in the US either, unless you're licensed and reclaim Freon from systems, not just bleed them down. -- Click Here for CaddyInfo page on "How To" Read Your OBD Codes-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data -- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC Yes, I was Jims_97_ETC before I changed cars. Link to comment Share on other sites More sharing options...
JimD Posted June 2, 2010 Report Share Posted June 2, 2010 You can buy all the R134 you want at WalMart. You need a license to buy R12. Jim Drive your car. Use your cell phone. CHOOSE ONE ! Link to comment Share on other sites More sharing options...
OynxSTS Posted June 3, 2010 Author Report Share Posted June 3, 2010 It's not legal to buy Freon in the US either, unless you're licensed and reclaim Freon from systems, not just bleed them down. Its not Freon, its R134a. Pretty sure they haven't used Freon in any Caddy since the early 90's Easin' down the highway in a new Cadillac, I had a fine fox in front, I had three more in the back ZZTOP, I'm Bad I'm Nationwide Greg Link to comment Share on other sites More sharing options...
Cadillac Jim Posted June 3, 2010 Report Share Posted June 3, 2010 Got me. It's been too long since I have done any hands-on A/C work. Please forgive any misunderstandings. -- Click Here for CaddyInfo page on "How To" Read Your OBD Codes-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data -- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC Yes, I was Jims_97_ETC before I changed cars. Link to comment Share on other sites More sharing options...
JimD Posted June 3, 2010 Report Share Posted June 3, 2010 Done deal. Jim Drive your car. Use your cell phone. CHOOSE ONE ! Link to comment Share on other sites More sharing options...
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