HELP — external temperature showing three dashes -- NO HEAT OR AC

[Zachfinch76]

I assumed this is because of the ambient temp sensor located in the front bumper l. So I changed it this morning. No dice. Still just see 3 dashes. What else could it be?

 

[ProjectSHO89]

What else could it be?

It could be the wiring or it could be the HVAC module.

[edit] Or the PCM... or something in between all that.

 

[Zachfinch76]

It could be the wiring or it could be the HVAC module.

Thank you! I did a bit or checking on wiring and I didn’t see any suspects. Other than the ambient temp showing three dashes I also have no air coming out of the hvac no matter what setting. High low auto nothing works not ac or heat. So maybe it is that hvac control module. Where is that located in the car? Thank you!

 

[peterk9]

Thank you! I did a bit or checking on wiring and I didn’t see any suspects. Other than the ambient temp showing three dashes I also have no air coming out of the hvac no matter what setting. High low auto nothing works not ac or heat. So maybe it is that hvac control module. Where is that located in the car? Thank you!

Welcome to the Forum.
I found the following in the 2011-2015 component views. Look at the bottom near the #5. Is that what you're looking for?

Peter

 

[Zachfinch76]

Welcome to the Forum.
I found the following in the 2011-2015 component views. Look at the bottom near the #5. Is that what you're looking for?

View attachment 431679



Peter

Thank you and Thank you! I read somewhere that to swap out this hvac ecu I am supposed to back up the programming of the existing one and restore it into the new one using some tool? Is that really true? It seems kind of strange since if the unit is bad who knows if I can even read any data from it?

 

[peterk9]

Sorry, I'm not familiar with that. I don't work on my own vehicles but perhaps another member may be able to answer that. Good luck.

Peter

 

[ProjectSHO89]

You're getting the cart before the horse. You don't even know what the fault is so any replacement activity discussion is premature.

If there is no valid ambient air temperature data, the system will not enable the operation of the A/C system.

You need to scan both the PCM and the HVAC module for any fault codes so you have a good starting point for diagnostics. You'll either need to become your own technician or you'll need to hire one to perform the needed diagnostic.

 

[Zachfinch76]

You're getting the cart before the horse. You don't even know what the fault is so any replacement activity discussion is premature.

If there is no valid ambient air temperature data, the system will not enable the operation of the A/C system.

You need to scan both the PCM and the HVAC module for any fault codes so you have a good starting point for diagnostics. You'll either need to become your own technician or you'll need to hire one tp perform the needed diagnostic.

Thank you. Can I use a pc and some software to do that? What cable do I need?

 

[ProjectSHO89]

Windows PC with free extended license.

Go to www.forscan.org for details included recommended interfaces.

 

[Zachfinch76]

Windows PC with free extended license.

Go to www.forscan.org for details included recommended interfaces.

Thanks. Does Forscan have the ability to detect and distinguish the difference between a wiring issue vs the hvac ecu module etc?

 

[peterk9]

I assumed this is because of the ambient temp sensor located in the front bumper l. So I changed it this morning. No dice. Still just see 3 dashes. What else could it be?

Did you perform a reset? According to a post in another thread that has to be done.
NOTE: If replacing the Ambient Air Temperature sensor a reset must be performed. Select the A/C and Recirc buttons simultaneously, then release both, Within 2 seconds select A/C button again.

Peter

 

[Zachfinch76]

Did you perform a reset? According to a post in another thread that has to be done.
NOTE: If replacing the Ambient Air Temperature sensor a reset must be performed. Select the A/C and Recirc buttons simultaneously, then release both, Within 2 seconds select A/C button again.

Peter

Can you point me tot he post? Like do I hold down those 2 buttons for a few seconds or? And is this with the climate system on or off? Car running or not? thanks

 

[peterk9]

It doesn't say much more than what I posted. Ambient Air Temp Sensor Replacement You can try it with the vehicle running and with it OFF. I would think that it would at least have to be in accessory mode in order to power those buttons.
There is also another thread on the ambient air issue and here is the first post; Ambient Air Temperature Issue

Peter

 

[Zachfinch76]

It doesn't say much more than what I posted. Ambient Air Temp Sensor Replacement You can try it with the vehicle running and with it OFF. I would think that it would at least have to be in accessory mode in order to power those buttons.
There is also another thread on the ambient air issue and here is the first post; Ambient Air Temperature Issue

Peter

Strange, this morning when I first turned on the car it did show an external temp reading -- so to test the system I press max ac and it turned on and blew full blast. I then turned it back off and drove about 5 min to the store. By the time I got back in the car it was stuck on the same temp reading, 61F on the screen, but --- in the small info area in the instrument cluster area, and would no longer engage the hvac system when I pressed the button. So I do not know what this points to. A short? A reset needed? A bad component that is finicky? Not sure. I ordered the Forscan usb attachment so I will see if I am able to get any useful info once I have it.

 

[Zachfinch76]

Strange, this morning when I first turned on the car it did show an external temp reading -- so to test the system I press max ac and it turned on and blew full blast. I then turned it back off and drove about 5 min to the store. By the time I got back in the car it was stuck on the same temp reading, 61F on the screen, but --- in the small info area in the instrument cluster area, and would no longer engage the hvac system when I pressed the button. So I do not know what this points to. A short? A reset needed? A bad component that is finicky? Not sure. I ordered the Forscan usb attachment so I will see if I am able to get any useful info once I have it.

I should also mention that all within a relatively short period of time I also have two other issues: TPMS fault, although the tire place said all sensors are functioning, making me thing it is the module. Keyless entry not working. And lastly, GPS signal is gone most of the time, comes for a second or two and is lost again.

 

[Zachfinch76]

Latest on this is I ran Forscan and I got DTC errors for HVAC Module not communicating with BCM Module. I reset both modules but it comes back every time when rerun. I do not know if this is sufficient info for me to assume the HVAC module is bad or if it could still be a wiring issue. I suppose I will not know until I try and replace the unit?

 

[ProjectSHO89]

Post the actual DTCs.

If the HVAC module cannot communicate with the PCM, the HVAC module can't get the AAT data which comes from the PCM via the BCM which acts as the gateway (bridge) between the HS-Can and MS-CAN busses.

 

[peterk9]

Latest on this is I ran Forscan and I got DTC errors for HVAC Module not communicating with BCM Module. I reset both modules but it comes back every time when rerun. I do not know if this is sufficient info for me to assume the HVAC module is bad or if it could still be a wiring issue. I suppose I will not know until I try and replace the unit?

Did you try the reset?

 

[Zachfinch76]

Did you try the reset?

OK I will copy/paste the DTCs later today. Thanks

I tried the reset following the steps, there were two I found, the AC and Recirc method and another which said power and defrost, both did not seem to do anything. I also pulled the fuse and also disconnected the battery. And also reset the module from within Forscan, none of that made any difference.

 

[Zachfinch76]

Post the actual DTCs.

DTCs:
APIM:
Code: U0140 - Lost Communication With Body Control Module

Status:
- DTC Present at Time of Request
- Malfunction Indicator Lamp is Off for this DTC

Module: Accessory Protocol Interface Module

FCIM:
Code: U0155 - Lost Communication With Instrument Panel Cluster (IPC) Control Module

Status:
- DTC Present at Time of Request
- Malfunction Indicator Lamp is Off for this DTC

Module: Front Controls Interface Module


IPC:

Code: U0424 - Invalid Data Received From HVAC Control Module

Additional Fault Symptom:
- Invalid Serial Data Received

Status:
- Previously Set DTC - Not Present at Time of Request
- Malfunction Indicator Lamp is Off for this DTC

Module: Instrument Panel Control Module

Code: U0424 - Invalid Data Received From HVAC Control Module

Additional Fault Symptom:
- Alive/Sequence Counter Incorrect/Not Updated

Status:
- DTC Present at Time of Request
- Malfunction Indicator Lamp is Off for this DTC

Module: Instrument Panel Control Module


RTM:

Code: U0140 - Lost Communication With Body Control Module

Additional Fault Symptom:
- Missing Message

Status:
- DTC Maturing - Intermittent at Time of Request
- Malfunction Indicator Lamp is Off for this DTC
- Test not complete

Module: Radio Transceiver Module

HVAC:
Code: U0140 - Lost Communication With Body Control Module

Status:
- Previously Set DTC - Not Present at Time of Request
- Malfunction Indicator Lamp is Off for this DTC
- Test not complete

Module: Heating Ventilation Air Conditioning

GPSM:
Code: U0140 - Lost Communication With Body Control Module

Status:
- Previously Set DTC - Not Present at Time of Request
- Malfunction Indicator Lamp is On for this DTC

Module: Global Positioning System Module