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Direct, indirect TPMS on Grand Prix

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Direct, indirect TPMS on Grand Prix

SUBJECT VEHICLE: 2004-08 Pontiac Grand Prix.

RELEARN PROCEDURE? Yes.

SPECIAL TOOLS NEEDED? Yes, on 2007-08 models, a J-46079 TPMS activation tool is needed.

The tire pressure monitoring system (TPMS) on Pontiac Grand Prix vehicles manufactured between 2004 and 2008 differ depending on the year range. In this article procedures are listed separately for 2004-06 models and 2007-08 vehicles.

TPMS 2004-06

NOTE: 2004-06: When a wheel is replaced or rotated, tire pressure has been adjusted or vehicle’s battery has been disconnected, the TPMS will need to be recalibrated. See tire pressure monitor system recalibration (2004-06).

NOTE: 2004-06 vehicles are equipped with indirect TPMS and DO NOT have tire pressure sensors mounted on the wheels.

The TPMS alerts the driver when a large change in the pressure of one tire exists while the vehicle is being driven. It uses the electronic brake control module (EBCM), anti-lock brake system (ABS) wheel speed sensor inputs, class 2 serial data circuit, instrument panel cluster (IPC) message center, and the driver information center (DIC) to perform the system functions. The EBCM contains the software to calculate relative tire pressure differences.

Once the TPMS has learned the tire pressure calibration, the EBCM monitors the ABS wheel speed sensor inputs. If the pressure increases or decreases in a tire, that tire’s circumference and radius will change, causing that wheel speed sensor input to change.

The EBCM recognizes this change in wheel speed as a tire pressure condition. If the pressure in one tire becomes at least 7 psi to 10 psi (48 to 69 kPa) lower or higher than the others, the EBCM commands the IPC to illuminate a low pressure tire warning indicator and the DIC to display a “CHECK TIRE PRESSURE” warning message (unless the pressure is high or low in more than one tire, if vehicle speed is above 70 mph (113 km/h), or the system is not completely calibrated). The system does not alert the driver to which tire pressure is high or low.

CAUTION: Any ABS or traction control operation may temporarily suspend TPMS operation.

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NOTE: The IPC message center “CHECK TIRE PRESSURE” warning message is ranked as lowest priority, and may not be displayed if a higher priority display is requested at the same time. Under the following conditions, the system may not function properly:

• More than one tire is low.

• Only one tire is replaced with a new tire during service.

• The vehicle is moving faster than 70 mph (113 km/h).

• The system is not yet calibrated.

• Tire tread wear is uneven.

• A compact spare tire is installed.

• Tire chains are being used.

• The vehicle is being driven on a rough or frozen road.

• If the ABS warning light is on.

TPMS 2007-08

NOTE: 2007-08: The sensor learn procedure must be performed after every tire rotation, remote control door lock receiver (RCDLR) replacement, or sensor replacement. See tire pressure sensor learn (2007-08).

NOTE: 2007-08 vehicles are equipped with direct TPMS and the vehicles DO HAVE sensors mounted on the wheels.

The system uses the IPC, DIC, RCDLR, keyless entry transmitter(s), rear window antenna grid, a radio frequency transmitting pressure sensor in each wheel/tire assembly, and the serial data circuit to perform the system functions.

The sensors continuously compare their last pressure sample to their current pressure sample and will transmit in re-measure mode if a 1.2 psi change in tire pressure has been detected in either a stationary or rolling state.

TPMS recalibration 2004-06

NOTE: On the GXP models, the front and rear tires are different sizes, and tire rotation is not recommended. CAUTION: DO NOT recalibrate TPMS until all problems are fixed and tire pressure in all four tires has been adjusted. If recalibration is done when tire pressures are incorrect, the TPMS will not work properly and may not set an alert when a tire pressure is low or high.

1. Turn the ignition to OFF.

2. Ensure all tire pressures are adjusted according to the tire pressure label.

3. Turn the ignition switch to the ON position, with engine off.

4. Press the vehicle information button until “TIRE INFLATION MONITOR SYSTEM PRESS (down/left arrow) SWITCH TO RESET” is displayed.

5. If the system is being reset due to a low tire pressure condition, press and hold the down/left arrow button until “TIRE INFLATION MONITOR SYSTEM HAS BEEN RESET” is displayed. If the system is being reset due to a tire rotation, press and hold the down/left arrow button for five seconds.

6. Release the down/left arrow button and “TIRE PRESSURE NORMAL” is displayed.

7. After resetting, the TPMS requires up to five miles of flat, smooth road, straight line driving in each of the four speed ranges (about 10-20 minutes in each range) to complete the calibration process: 19 to 40 mph; 40 to 59 mph; 59 to 74.5 mph; and 74.5 to 90 mph.

NOTE: The learning process does not need to be completed during a single trip.

Tire pressure sensor learn 2007-08

NOTE: The sensor learn procedure must be performed after every tire rotation, RCDLR replacement, or sensor replacement. A J-46079 TPMS activation tool is needed.

Once the learn mode has been enabled, each sensor’s unique identification codes can be learned into the RCDLR memory, when it 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 learned IDs are assigned in the following order: left-front; right-front; right-rear; and left-rear. The turn signals will individually illuminate indicating which location is to be learned in the proper sequence.

Each sensor takes a pressure measurement sample once every 30 seconds while in stationary mode. If the pressure increases or decreases by more than 8.3 kPa (1.2 psi) from the last measurement, another measurement will occur immediately to verify the change in pressure.

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If a pressure change has indeed occurred, the sensor transmits in learn mode. When the RCDLR receives a learn mode transmission while in TPMS learn mode, it will assign that sensor ID to the location on the vehicle relative to the order in which it was learned.

NOTE: The learn mode will cancel if the ignition is cycled to OFF or if more than two 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.

IMPORTANT: Before proceeding, ensure that no other learn procedure is being performed simultaneously or that tire pressures are not being adjusted on another TPMS-equipped vehicle within close proximity. Stray signals from other TPMS-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 TPMS learn procedure away from other vehicles is highly recommended. In the event particular sensor pressure increase/decrease 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 being blocked by another component.

1. Place the ignition switch in the proper position as follows:

• With a standard ignition switch, place the switch in the RUN position.

• With an electronic keyless ignition, place the switch in the ACCY position.

2. Use one of the following methods to enable learn mode:

• Using a scan tool, initiate the TPMS learn mode. A double horn chirp will sound indicating the learn mode has been enabled. The left-front turn signal will also be illuminated.

• On vehicles equipped with keyless entry, simultaneously press the keyless entry transmitter’s 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 DIC INFO button until the RELEARN TIRE POSITIONS message appears on the DIC display. Press the SET/RESET button until a double horn chirp sounds and the DIC displays TIRE LEARNING ACTIVE, indicating the learn mode has been enabled.

3. Use one of the following methods to activate each sensor:

• Hold the antenna of the 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; the turn signal in the next location to be learned will illuminate.

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

4. After the horn chirp has sounded and the right-front turn signal is illuminated, repeat step 3 for the remaining three sensors in the following order: right-front; right-rear; left rear.

5. After the left-rear sensor has been learned, a double horn chirp will sound indicating all sensors have been learned.

6. Turn off the ignition to exit the learn mode.

7. After the learn mode has been exited, adjust all tires to the recommended pressures. Refer to the vehicle’s certification, tire placard, anti-theft and service parts ID label.

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Demounting/mounting procedures

NOTE: If the vehicle’s tires are replaced with those not having a TPC Spec number, the TPMS may give an inaccurate low pressure warning. Non-TPC Spec tires may give a low pressure warning that is higher or lower than the proper warning level achieved by TPC Spec-numbered tires.

NOTE: 2007-08: The sensor learn procedure must be performed after every tire rotation, RCDLR replacement, or sensor replacement. See tire pressure sensor learn 2007-08.

Tire pressure indicator sensor replacement 2007-08

1. Raise the vehicle on a suitable support.

2. Remove the tire/wheel assembly from the vehicle. IMPORTANT: Before the tire is removed from the wheel, note the following items to avoid tire pressure sensor damage.

• Place the sensor’s cap and valve on a dry, clean surface after removal. The cap is aluminum and the valve is nickel-plated to prevent corrosion and are not to be substituted with a cap or valve made of any other material.

• When separating the tire bead from the wheel, position the bead-breaking fixture 90 degrees from the valve stem.

• Position the mounting/demounting head so the tire iron or pry bar can be inserted slightly clockwise of the sensor body when prying the tire bead up and over the mounting/demounting head.

• Rotate the tire/wheel assembly clockwise when transferring the tire bead to the outside of the wheel rim.

• Repeat items for the inner bead.

IMPORTANT: If any tire sealant is noted upon tire demounting; remove all residual liquid sealant from the inside of the tire and wheel surfaces.

3. Remove the tire from the wheel.

4. Remove the tire pressure sensor nut.

5. Remove the tire pressure sensor.

Installation procedure

1. Clean any dirt or debris from the grommet sealing area.

2. Insert the sensor in the wheel hole with the air passage facing away from the wheel. See Figure 1.

IMPORTANT: Before reinstalling the tire on the wheel, note the following items to avoid tire pressure sensor damage upon tire mounting.

• Position the mounting/demounting head 180 degrees from the valve stem.

• Position the bead transition area 45 degrees counter clockwise of the valve stem.

• Rotate the tire/wheel assembly clockwise when transferring the tire bead to the inside of the wheel rim.

• Repeat items for the outer bead.

3. Install the sensor nut and position the sensor body parallel to the inside wheel surface while torquing. See Figure 2. Tighten the sensor nut to 7 Nm (62 in.-lbs).

IMPORTANT: A service replacement tire pressure sensor is shipped in the OFF mode. In this mode the sensor’s unique identification code cannot be learned into the RCDLR memory. The sensor must be taken out of OFF mode by spinning the tire/wheel assembly above 25 mph (40 km/h) in order to close the sensors internal roll switch for at least 10 seconds.

4. Install the tire on the wheel.

5. Install the tire/wheel assembly on the vehicle.

6. Lower the vehicle.

7. Learn the tire pressure sensors. Refer to tire pressure sensor learn (2007-08).    ■

Information for this column comes from Mitchell 1’s ”Tire Pressure Monitoring Systems Guide” for domestic and import vehicles through 2012. Headquartered in Poway, Calif., Mitchell 1 has provided quality repair information solutions to the automotive industry for more than 80 years. For more information, visit www.mitchell1.com.

 

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