TPMS service light

Yes. Most likely this is the module. I attached the process. However, you need to run through the test I attached and see if the cluster is the issue. I doubt it is but just make sure this is ok as it is an easy test.

More than likely the module is just not picking up the signal from one of the sensors and it is turning this warning on.

Let us know what you find and we can go from there. Thanks

This depends on a number of things and could be related to each other. However, the transmission control code is not related to the TPMS issue.

If both codes were set at the same time then neither of them could be related to the TPMS issue.

It is very common for general bus issues to cause issues in the TPMS because this operates on an RF signal and are sensitive to bus interruptions.

Do you know which module set the U0073? That will tell us if there is something else going on or not.

Ok. Did the scan tool tell you which module it came from? I am sure the P0700 was from the TCM but the U0073 is what we need to confirm.

Okay. That makes sense that it could be the TCM but that will probably not fix the TPMS issue.

Okay. You are partly correct. You have two types of bus networks on this vehicle. A high speed bus and a low speed bus. The High speed is used for the modules to communicate with each other and when one of them like the TCM is offline the BCM will set a U code against that module like you have. However, the difference is if the TCM were offline all the time, you would have a lot of codes and the performance of the vehicle would be effected. This means that the TCM had an issue at some point and it set these bus off performance codes but it is not active currently. That means there is no real way to diagnose that code because the issue is not currently there.

One way to test this is to go to the TCM or BCM and check for proper bus voltage. If you get on any of the bus wires, you should have about 2.5volts. Basically the + and - bus wires need to add up to 5 volts so if one is 2.7 volts the other should be 2.3 volts when measured with a multi-meter. The bus off performance code happens when one leg of this network get pulled high or low and the total voltage no longer equals 5 volts. For example the + is 3.5v and the - is normal at 2.3 v.

All this to say, the TPMS light is currently on correct? If that is the case then you have an issue with that system but unless these bus codes are currently active they are unlikely the cause of the TPMS light.

Also, as for the replacement or re-flash of the TCM, that may work if the TCM is in fact the issue. At this point, based on experience I don't see enough to say the TCM will fix these codes or turn off the TPMS light.

What I would suggest is measuring the bus voltage and going from there. If the bus is off then the TPMS is the most sensitive module. So if we can get a little more evidence then we would have more to go on and replacing the TCM won't be so much of a guess.

Okay. That is a good idea. If they return then that means that the issues is continuing to happen but with a bus issue it may only be a momentary issue. So by the time you test it, the issue is no longer there.

As for testing the bus voltage, it doesn't matter. It is the same anywhere you test it. Think of it like a closed circuit television. No matter where you view the TV it is the same picture if you are on that closed circuit.

Okay. That is good news. Now we can rest assured that we are dealing with just a TPM issue and not a greater electrical issue.

Based on the fact that the light is on and you are getting a message in the message center you have a malfunction in the TPM system. Since the sensors are all new, we can assume it is the remote control door lock receiver module as this is what the BCM uses to pick up the RF signal from the sensors and transmits them to the BCM who shares it with the cluster.

The proper way to diagnose this is using a scan tool but if it were me, I would just replace it and then relearn the module and then all the sensors. Unfortunately you will need to program this module using a scan tool but any shop that has one capable can do that pretty easily.

Sounds great. Let us know what happens. Thanks

There is a specific procedure that must be performed to have the CAN work with the sensors.

Tire Pressure Indicator Sensor Learn

Special Tools

- EL-46079/J-46079 Tire Pressure Monitor Diagnostic Tool

Learn Mode Description

The tire pressure monitor (TPM) system uses the instrument panel cluster (IPC), body control module (BCM), remote control door lock receiver (RCDLR), keyless entry transmitter, 4 radio frequency transmitting pressure sensors, and the serial data circuit to perform the TPM learn mode functions. The sensor learn procedure must be performed after every tire rotation, RCDLR replacement, or sensor replacement. Once the learn mode has been enabled, each of the sensors unique identification codes can be learned into the RCDLR memory. When a sensor ID has been learned, the RCDLR sends a serial data message to the BCM to sound a horn chirp. This verifies the sensor has transmitted its ID and the RCDLR has received and learned it. The RCDLR must learn the sensor IDs in the proper sequence to determine correct sensor location. The first learned ID is assigned to the left front location, the second to right front, the third to right rear and the fourth to left rear. The turn signals will individually illuminate indicating which location is to be learned in the proper sequence.

Sensor Functions Using J-46079

Each sensor has an internal low frequency coil. When the EL-46079/J-46079 is used in activate mode, it produces a low frequency transmission that activates the sensor. The sensor responds to a low frequency activation by transmitting in learn mode. When the RCDLR receives a learn mode transmission while in TPM learn mode, it will assign that sensors ID to the location on the vehicle relative to the order in which it was learned.

Sensor Functions Using Pressure Increase/Decrease Method

Each sensor takes a pressure measurement sample once every 30 seconds while in stationary mode. If the tire pressure increases, or decreases by more than 8.3 kPa (1.2 psi) from the last pressure measurement, another measurement will occur immediately to verify the change in pressure. If a pressure change has indeed occurred, the sensor transmits in Learn mode. When the RCDLR receives a Learn mode transmission while in TPM learn mode, it will assign that sensor's ID to the location on the vehicle relative to the order in which it was learned.

Learn Mode Cancellation

The learn mode will cancel if the ignition is cycled to OFF or if more than 2 minutes has elapsed for any sensor that has not been learned. If the learn mode is cancelled before the first sensor is learned, the original sensor IDs will be maintained. If the learn mode is canceled after the first sensor is learned, the following will occur:

- All stored sensor IDs will be invalidated in the RCDLR memory.
- If equipped, the DIC will display dashes instead of tire pressures.
- DTC C0775 will be set.

These conditions will now require the learn procedure to be repeated for the system to function properly.

TPM Learn Procedure

Important: If using the scan tool to enable the learn mode, the EL-46079/J-46079 must be used to activate the sensors. When this preferred method is used, any stray sensor signals will not affect the learn procedure. In the event a particular sensor's information is displayed on the special tool upon activation but the horn does not chirp, it may be necessary to rotate the wheel valve stem to a different position due to the sensor signal is being blocked by another component. If using the keyless entry transmitter or DIC buttons to enable the learn mode, the EL-46079/J-46079 or Pressure Increase/Decrease Method may be used. Before proceeding with this method, ensure that no other learn procedure is being performed simultaneously or that tire pressures are not being adjusted on another TPM equipped vehicle within close proximity. Stray signals from other TPM equipped vehicles just driving by can be inadvertently learned. If any random horn chirps are heard from the vehicle while performing the learn procedure, most likely a stray sensor has been learned and the procedure will need to be cancelled and repeated. Under these circumstances, performing the TPM Learn Procedure away from other vehicles would be highly recommended. In the event a particular sensor activation does not cause the horn to chirp, it may be necessary to rotate the wheel valve stem to a different position due to the sensor signal is being blocked by another component.

Preferred Scan Tool Learn Enable Method

1. Using a scan tool, initiate the TPM Learn Mode. A double horn chirp will sound indicating the Learn Mode has been enabled. The left front turn signal will also be illuminated.
2. Starting with the left front tire, active the sensor by holding the antenna of the EL-46079/J-46079 aimed upward against the tire sidewall close to the wheel rim at the valve stem location. Press and release the Activate button and wait for a horn chirp. Once the horn chirp has sounded, the sensor information is learned and the turn signal in the next location to be learned will illuminate.
3. After the horn chirp has sounded and the right front turn signal is illuminated, repeat step 2 for the remaining 3 sensors in the following order:

3.1 Right front
3.2 Right rear
3.3 Left rear

4. When the left rear sensor has been learned and a double horn chirp has sounded, the learn process is complete and the RCDLR exits the learn mode.
5. Ignition OFF, adjust all tires to the recommended pressures. Refer to Vehicle Certification, Tire Placard, Anti-Theft, and Service Parts ID Label.

Alternate Keyless Entry Transmitter or DIC Learn Enable Method

1. Ignition ON, initiate the TPM Learn Mode using one of the following procedures:

- On vehicles equipped with keyless entry, simultaneously press the keyless entry transmitters lock and unlock buttons until a double horn chirp sounds indicating the Learn Mode has been enabled. The left front turn signal will also be illuminated.
- On vehicles not equipped with keyless entry, press and release the driver information center (DIC) INFO button until the TIRE LEARN message appears on the DIC display. Press and hold the SET/RESET button until a double horn chirp sounds indicating the Learn Mode has been enabled. The left front turn signal will also be illuminated.

2. Starting with the left front tire, learn the tire pressure using one of the following methods:

- Hold the antenna of the EL-46079/J-46079 aimed upward against the tire sidewall close to the wheel rim at the valve stem location. Press and release the activate button and wait for a horn chirp. Once the horn chirp has sounded, the sensor information is learned and the turn signal in the next location to be learned will illuminate.

Caution: Over inflating tires may cause personal injury or damage to the tires and wheels. When increasing tire pressure do not exceed the maximum inflation pressure as noted on the tire sidewall.

- Increase/decrease the tire pressure for 8 10 seconds then wait for a horn chirp. The horn chirp may occur before or up to 30 seconds after the 8 10 second pressure increase/decrease time period has been reached. Once the horn chirp has sounded, the sensor information is learned and the turn signal in the next location to be learned will illuminate.

3. After the horn chirp has sounded and the right front turn signal is illuminated, repeat step 2 for the remaining 3 sensors in the following order:

3.1 Right front
3.2 Right rear
3.3 Left rear

4. When the left rear sensor has been learned and a double horn chirp has sounded, the learn process is complete and the RCDLR exits the learn mode.
5. Ignition OFF, adjust all tires to the recommended pressures. Refer to Vehicle Certification, Tire Placard, Anti-Theft, and Service Parts ID Label.

Also you can see whats going if with a simple CAN scanner you can get from amazon for about $40.00. here is a video to show you how:

https://youtu.be/InIlnsjOVFA

Please run down this guide and report back.

Okay. The fact that this is acting the way it is, you are correct that the DIC is the issue or there is a greater issue.

Keep in mind, the TPS is the most sensitive module on the vehicle and it requires communicating between the PCM, Cluster, RCDLR, DIC.

It communicates on this CAN network and if there is a interruption on this then something is not able to communicate. With this system being the most sensitive then it would explain the erratic action you are seeing.

However, it sounds like the RCDLR is sending out the signal to the DIC but this may not be broadcasting the signal on the BUS. So if it were me I would replace it and see what happens.