HVAC fault codes question.

[gregsmy]

Did a little work with my AC issues. One of my possible issues might have had to do with the actuators. So I connected my bi-directional scan tool and checked for codes and ran the learn function for the actuators as well as a few other tests. There where a number of codes stored in the system. I went ahead and ran a report and then erased codes. There are a number of codes that just comeback immediately, like a hard fault. Looking for any insight as to what the problem might be. These are the codes listed under the HVAC control module:

B0413-04 Temperature control 1 feedback circuit open
B0433-04 Temperature control 3 feedback circuit open
B3782-04 Air flow control 10 feedback circuit open

The HVAC seems to operate normally other than my low freon situation.

There is also a code listed for the Body Control Module that keeps coming back:

U0200-00 Lost communication with the door control module B

And a couple listed for the Vehicle Comm. Interface Module:

B1000-3C Electronic control unit (ECU) performance
B2470=04 Cellular phone antenna open circuit

And a code under the Engine Control Module:

P0521-00 Engine oil pressure sensor performance

This one relates to the weird situation I have with my oil pressure gauge. Most of the time the gauge reads correctly, but occasionally the needle will swing back and forth like 20 pounds. I was planning on starting a separate post in the engine section about this problem and what I have already done and replaced.

 

[OR VietVet]

And a code under the Engine Control Module:

P0521-00 Engine oil pressure sensor performance

This one relates to the weird situation I have with my oil pressure gauge. Most of the time the gauge reads correctly, but occasionally the needle will swing back and forth like 20 pounds. I was planning on starting a separate post in the engine section about this problem and what I have already done and replaced.


@gregsmy, use your scanner live data function and get the voltage readings for your oil pressure. That will tell you if the sender/sensor is working or not. If that is accurate, then, like my recent oil pressure fluctuation problems, the stepper motor in the dash cluster is likely the problem. Then find a cluster fixer upper or do some digging on replacing the stepper motor yourself.

See oil pressure voltages below:

 

[gregsmy]

And a code under the Engine Control Module:

P0521-00 Engine oil pressure sensor performance

This one relates to the weird situation I have with my oil pressure gauge. Most of the time the gauge reads correctly, but occasionally the needle will swing back and forth like 20 pounds. I was planning on starting a separate post in the engine section about this problem and what I have already done and replaced.


@gregsmy, use your scanner live data function and get the voltage readings for your oil pressure. That will tell you if the sender/sensor is working or not. If that is accurate, then, like my recent oil pressure fluctuation problems, the stepper motor in the dash cluster is likely the problem. Then find a cluster fixer upper or do some digging on replacing the stepper motor yourself.

See oil pressure voltages below:

View attachment 450819

I will see if I can find that information with my scan tool. Did you have a thread on your issue?

 

[Fless]

2007-up should have a PID for oil pressure; there shouldn't be a need to convert sensor voltages.

 

[OR VietVet]

@Fless gave me that voltage info but that was for a 2004 Silverado

 

[swathdiver]

Did a little work with my AC issues. One of my possible issues might have had to do with the actuators...

What are you driving friend?

 

[Fless]

What are you driving friend?

2010 Suburban from his other thread: https://www.tahoeyukonforum.com/threads/ac-charge-question.153110/

It would be helpful to have vehicle info in the signature so it's always there to reference.

 

[swathdiver]

Did a little work with my AC issues. One of my possible issues might have had to do with the actuators. So I connected my bi-directional scan tool and checked for codes and ran the learn function for the actuators as well as a few other tests. There where a number of codes stored in the system. I went ahead and ran a report and then erased codes. There are a number of codes that just comeback immediately, like a hard fault. Looking for any insight as to what the problem might be. These are the codes listed under the HVAC control module:

B0413-04 Temperature control 1 feedback circuit open
B0433-04 Temperature control 3 feedback circuit open
B3782-04 Air flow control 10 feedback circuit open

The HVAC seems to operate normally other than my low freon situation.

There is also a code listed for the Body Control Module that keeps coming back:

U0200-00 Lost communication with the door control module B

And a couple listed for the Vehicle Comm. Interface Module:

B1000-3C Electronic control unit (ECU) performance
B2470=04 Cellular phone antenna open circuit

And a code under the Engine Control Module:

P0521-00 Engine oil pressure sensor performance

This one relates to the weird situation I have with my oil pressure gauge. Most of the time the gauge reads correctly, but occasionally the needle will swing back and forth like 20 pounds. I was planning on starting a separate post in the engine section about this problem and what I have already done and replaced.

Keep your GM vehicle all GM. The computers in these trucks don't like aftermarket components.

All of those actuators are in need of replacement if those are current and not historical codes.

B1000 C3, Your ECM has an internal short and ought to be replaced.

U0200 00, Might be related to the B1000, don't know, it's not in my list.

P0521 00, You need a new oil pressure sensor. If AFM is active, replace the filter underneath it too.

B2470 04, I used to get this one. It was caused by water getting past the roof antenna and running down the celluar coax cable. Code went away when it dried out. A thin bead of clear RTV around the base of the antenna fixed this. Car Washes wear away the RTV over time, beware.

 

[OR VietVet]

So, I guess the oil pressure voltage readings that @Fless gave me, are for GMT800 trucks?

 

[gregsmy]

What are you driving friend?

Updated my signature line with vehicle info.

 

[Fless]

So, I guess the oil pressure voltage readings that @Fless gave me, are for GMT800 trucks?

Yes

 

[gregsmy]

Keep your GM vehicle all GM. The computers in these trucks don't like aftermarket components.

All of those actuators are in need of replacement if those are current and not historical codes.

B1000 C3, Your ECM has an internal short and ought to be replaced.

U0200 00, Might be related to the B1000, don't know, it's not in my list.

P0521 00, You need a new oil pressure sensor. If AFM is active, replace the filter underneath it too.

B2470 04, I used to get this one. It was caused by water getting past the roof antenna and running down the celluar coax cable. Code went away when it dried out. A thin bead of clear RTV around the base of the antenna fixed this. Car Washes wear away the RTV over time, beware.

AFAIK it has all the original GM actuators. Definitely the blend door actuator, as I removed it to confirm operation of the actuator and manually move the door to verify it was working. I opened up the actuator to look inside and everything looked good, went ahead and cleaned the location strips with a little alcohol.

Do you know which actuators are 1,3 and 10? I can command them and see what information I get back. It seems like everything related to the doors (defrost, dash, floor, etc.) seems to be operating correctly.

B1000 C3, Your ECM has an internal short and ought to be replaced.

What ECM is this and where is it located?

 

[gregsmy]

P0521 00, You need a new oil pressure sensor. If AFM is active, replace the filter underneath it too.

I got the burb from a friend after the transmission died. It has a lot of miles and needed a fair bit of work other than the trans. So I went thru it from one end to the other looking for problems, known problems, and any maintenance it could need. I replaced the oil pressure sensor and screen with genuine GM parts. I also dropped the pan and replaced the pickup oring and installed a "baffle" on the oil squirter that was a TSB. Also replaced the valve cover on one side that was also covered by a TSB for oil consumption. I also use the recommended Delco oil filter. The engine was super clean inside as they had synthetic oil changes done on a regular basis. I also sent the engine ECU off to have the AFM turned off, but have not replaced any of the AFM internal parts. Engine runs great, no noises, minimal oil consumption for having 275,000 miles on the clock.

The gauge movement is strange to me. Its steady most of the time, but then without explanation the gauge will just swing up 20 pounds and back to normal. It might do this 2-3 times and then quit. Sometimes on a long drive it will move 5-10 pounds at a steady speed and engine rpm. I have found that if its in tow mode and not going into 6th gear so the rpm is higher, I dont see the gauge move as much on long rides.

 

[gregsmy]

For the HVAC actuators, I think I figured out that:

B0413 = Drivers Side air temperature actuator
B0433 = Auxiliary air temperature actuator (rear unit)
B3762 = Auxiliary mode actuator (rear unit)

Since I dont ride in the back I havent noticed an issue even though I leave the rear ac on all the time. I will get the scan tool connected and see what I can figure out on those.

 

[swathdiver]

What ECM is this and where is it located?

Your engine computer, under the dash behind the driver's side battery tray.

The gauge movement is strange to me. Its steady most of the time, but then without explanation the gauge will just swing up 20 pounds and back to normal. It might do this 2-3 times and then quit. Sometimes on a long drive it will move 5-10 pounds at a steady speed and engine rpm. I have found that if its in tow mode and not going into 6th gear so the rpm is higher, I dont see the gauge move as much on long rides.

New parts can fail, especially counterfeit ones.

For the HVAC actuators, I think I figured out that:

 

[gregsmy]

New parts can fail, especially counterfeit ones.

This is true. I think I have the old one I removed that was probably the original. I only replaced it because it was a known issue and to check the screen below it. If I can find it then I could swap it and see if the issue persists. If it changes or solves the problem then get another new one.

 

[gregsmy]

B1000 C3, Your ECM has an internal short and ought to be replaced.

This what I found from the manual:

DTC B1000 3C
- Electronic Control Unit (ECU) Performance Internal Communications Failure
Conditions for Clearing the DTC

* A current DTC clears when the malfunction is no longer present.
* A history DTC clears when the module ignition cycle counter reaches the reset threshold of 100, without a repeat of the malfunction.

Diagnostic Aids

* This DTC may be stored as a history DTC without affecting the operation of the control module.
* Do not replace a control module based only on DTC B1000 being set in history with the exception of the following control modules:

- Sensing and Diagnostic Module (SDM)
- Rollover Sensor
- Passenger Presence System Module


Not sure what its affecting currently, but I will see if anything changes before I would replace it.

 

[gregsmy]

Did a little thinking and then some research. I think the B1000 3C code in the ECU may be from the tuner "switching off" the AFM within the ECU. I had shipped the ECU off and had it done while I had the burb torn apart. I thought the idea of not having one of the Range products plugged into the obd port was better. Apparently you can get some of these codes if any tuning for performance has been done. The better tuners know about these issues and how to write the code without causing a problem. Again this is only a researched guess. But since it doesnt seem to cause a problem, and I wouldnt know about it unless I had my new scan tool I am not going to worry about it for now.

 

[gregsmy]

Update on the actuator codes. I used my scan tool to go in and test them and just look to see what I could do with it. After that I did the calibration a couple of times. Once with the ac on and then again with the hvac turned off. After a couple of days those codes have not come back yet. All the controls seem to operate correctly. I still need to put my gauges on it. I haven’t noticed it freezing up at the drier, but it did get to the 80’s past couple of days.

 

[gregsmy]

I was investigating the U0200-00 code for the door control module B communication. First I was trying to figure out which module that is and I think its the passenger side front door switch/control module. Next I double checked the operation of the mirror, door lock and window operation. From the drivers side I can operate everything normally. Next I went and opened the passenger door and tried to lower the window and lock the doors but nothing happened. I got inside the truck and closed the door and tried again and everything worked normally. Double checked the back doors and drivers door and they all work with the door open or closed. Any ideas?