Tire Pressure Monitor Systems Acura MDX I

MODEL COVERAGE

Models Covered

DESCRIPTION & OPERATION

Note. When a tire pressure sensor is replaced or tires are rotated, the sensor ID must be memorized by the TPMS control unit. See RESET PROCEDURES .

TIRE PRESSURE MONITOR (TPM) SYSTEM

Whenever the engine is running, the TPMS control unit continuously monitors all 4 tires and the system. The system has 6 indicators: 4 tire indicators, a low pressure indicator and a TPMS system indicator.

If the TPMS control unit detects pressure below the lower limit (as detailed in the table below for each model covered by this article), it alerts the driver by turning on the low pressure indicator, turning on the appropriate tire(s) indicator on the multi-information display, and setting a Diagnostic Trouble Code (DTC) in the control unit. When the tire pressure is increased to above the upper limit (as detailed in the table below for each model covered by this article) the control unit will turn off the indicators and store the DTC(s).

Tire Pressure Warning Threshold Limits

When 2 or more tire pressures are low, the low pressure indicator comes on about 5 seconds before the appropriate tire indicator. Once low pressure is detected, the system scans all 4 pressure sensors to ensure that it turns on the correct tire indicator.

If a problem is detected in the system, the TPMS indicator will come on. If low tire pressure and a problem in the system are detected, only the TPMS indicator comes on. When the system detects a problem, the TPMS control unit sets a code, but shifts to fail-safe mode, and does not alert the driver to low tire pressures. If the TPMS control unit loses power or fails, the TPMS indicator will come on, but no DTC will be set.

Each tire pressure sensor is an integrated unit made up of the tire valve stem, a pressure sensor, and a transmitter. The unit is attached to the inside of the wheel, around the valve stem. Each low pressure sensor has its own ID to prevent jamming by similar systems on other vehicles. After memorizing all the sensor ID(s), the control unit receives only those specific signals. An ID can be memorized manually or automatically.

An initiator for each wheel (located in wheelhousing) is hardwired to the control unit. Every time the ignition is turned ON (II), the control unit asks each initiator for a sensor ID. The initiators then transmit the sensor ID(s), and the control unit receives and memorizes them. The control unit then knows which ID belongs to each tire location. This recurring ID confirmation prevents any confusion in the system as a result of normal tire rotation.

TIRE PRESSURE MONITOR WARNING INDICATORS

Note. If a flat tire is replaced with the spare tire, and the flat tire is stored in the cargo area, the low pressure indicator will stay on but the appropriate tire indicator will go off. This prevents the customer from thinking there is a problem with the spare tire. When the flat tire is taken out of the vehicle for repair, the warning light will come on because the system is no longer receiving the signal from the tire's transmitter.

Note. If the temperature drops and then rises, tire pressure could decrease just enough to turn on the low pressure and tire(s) indicators, but later increase enough to turn them off. This can be an indication that tires pressures are near the minimum acceptable specification.

Note. If the outside temperature is at or below -40°F (-40°C), the system may not function properly.

If the TPMS control unit detects pressure below the lower limit (see Tire Pressure Warning Threshold Limits table), it turns on the low pressure indicator and the appropriate tire indicator(s) on the multi-information display, as well as the message indicator. When the tire pressure is increased to normal the control unit will turn off the indicators.

When 2 or more tire pressures are low, the low pressure indicator comes on about 5 seconds before the appropriate tire indicator.

If a problem is detected in the system, the TPMS indicator will come on. If low tire pressure and a problem in the system are detected, only the TPMS indicator comes on. When the system detects a problem, the TPMS control unit sets a code, but shifts to fail-safe mode, and does not alert the driver to low tire pressures. If the TPMS control unit loses power or fails, the TPMS indicator will come on.

If low tire pressure indicator and multi-information display indicator(s) are lit continuously due to low pressure in one or more tires, adjust tire inflation to proper pressure as indicated on the tire and loading information placard. The light will remain on until tire pressure is properly set. If warning light is still illuminated or the TPMS indicator is lit continuously, there is a problem in the TPM system. See appropriate manufacturer service information.

RESET PROCEDURES

Note. When a tire pressure sensor is replaced or tires are rotated, the sensor ID must be memorized by the TPMS control unit. See Memorizing Sensor ID (Automatically) . If the TPMS control unit has also been replaced, the Honda Diagnostic System (HDS) or a OBD-II compatible scan tool must be used to program information into new TPMS control unit. See Memorizing Sensor ID (Using HDS) .

When the tire pressure warning light illuminates and warning message appears, immediately check air pressure of all tires and adjust to the specified pressure. Ensure warning indicators go out.

TIRE PRESSURE SENSOR REGISTRATION

Note. Misalignment of the control unit and initiators could interfere with sending and receiving signals. Ensure brackets on TPMS control unit and front initiators are not bent.

Note. To ensure the control unit memorizes the correct ID, the vehicle with the new sensor must be at least 3 m (10 ft.) from any other TPMS pressure sensor not installed on that vehicle.

Memorizing Sensor ID (Automatically)

1. After rotating the tires or replacing a tire pressure sensor, drive the vehicle for at least 40 seconds at a speed of 15 mph (24 km/h) or more, and all the sensor ID(s) will be memorized automatically.
2. After the ID(s) are memorized, reduce the pressure in all 4 tires to less than the appropriate specification, and check to see that the 4 tire indicators come on.

Memorizing Sensor ID (Using HDS)

1. With the ignition switch in OFF position, connect the HDS to the 16-pin Data Link Connector (DLC) located under the left side of the dashboard.
2. Turn the ignition switch to ON position, and memorize the ID of the tire pressure sensor by following the screen prompts on the HDS. If all ID(s) are memorized properly, go to step 4 . If TPM control unit fails to memorize one or more sensor ID(s) during learning process, go to next step.
3. If one or more ID(s) fail to learn, causing DTC(s) to set, the HDS will provide a procedure to fix this that involves raising the vehicle. To solve this problem much faster, perform the following: Using HDS, clear all DTC(s). Using an assistant, start the learning process while driving the vehicle under 10 MPH. TPM control unit should now learn all 4 sensor ID(s). If TPM control unit is still having trouble learning ID(s), refer to appropriate service information.
4. After the ID(s) are memorized, reduce the pressure in all 4 tires to less than the appropriate specification, and check to see that the 4 tire indicators come on.

DISMOUNTING/MOUNTING PROCEDURES

Note. When a tire pressure sensor is replaced or tires are rotated, the sensor ID must be memorized by the TPMS control unit. See RESET PROCEDURES .

Note. Vehicles equipped with TPM system must use wheels made for the system, or system will not work. The original equipment wheels have an "STK" mark and a "TPMS" mark on them (some older wheels only have the "TPMS" mark), and a counterweight cast into the opposite side of the spoke to balance the weight of the sensor. (Scheme 4)

Scheme 4

TIRE PRESSURE SENSOR

Removal

1. Raise the vehicle, and support it with safety stands in the proper locations.
2. Remove wheel with faulty sensor.
3. Remove tire valve cap and valve core, and let the tire deflate.
4. Remove any balance weights, and then remove the tire from the wheel with a commercially available tire changer. Note these items to avoid damaging the tire pressure sensor: Do the outside of the wheel first. Position the wheel as shown so the valve stem is 90 degrees from the bead breaker. (Scheme 5) DO NOT position bead breaker of tire changer too close to the rim. Position the wheel so the tire machine and tire iron are next to the valve stem, and will move away from it when the machine starts. Then remove the tire from the wheel. (Scheme 6)
5. Remove and discard valve stem nut, then remove the tire pressure sensor and valve stem from the wheel and go to step 7. If valve stem nut cannot be removed by hand, spray valve stem with rust penetrant, then CAREFULLY remove the cap with pliers. If valve stem nut is seized on the valve stem, go to next step.
6. Slowly turn valve stem counterclockwise until tire pressure sensor drops off the end of the valve stem. Discard the screw, but keep the sensor. Ensure valve stem grommet is removed. Being careful not to damage wheel, use a power drill with a 11-mm drill bit to drill out the hole in the valve stem ball just enough to remove valve stem from wheel. (Scheme 7)
7. Remove and discard the valve stem and screw from the tire pressure sensor. (Scheme 8) NOTE: The valve stem grommet might stay in the wheel; make sure to remove it.

Scheme 5

Scheme 6

Scheme 7

Scheme 8

Installation

Note. Use a new nut, valve stem and screw.

1. Assemble the new valve stem, new screw, and the sensor-transmitter. (Scheme 8)
2. Before installing tire pressure sensor, clean the mating surfaces on the sensor and the wheel.
3. Install tire pressure sensor to the wheel, and tighten valve nut finger tight. Make sure sensor is resting on the wheel. see scheme 6
4. Tighten valve nut to 35 INCH lbs. (4 N.m) while holding the tire pressure sensor toward the wheel and taking the following precautions: Do not reuse any nuts that have been tightened (even one time) to the specified torque, as they are deformed inside. Do not use air or electric impact tools to tighten a valve stem nut. Tightening the nut beyond the specified torque can damage the nut. You may hear a snap or pop as you tighten the nut. This is normal. Make sure that there is no space between the sensor and the wheel.
5. Lube the tire bead, and position the wheel so the tire machine and tire iron are next to the valve stem and will move away from it when the machine starts. Then install the tire onto the wheel. (Scheme 6)
6. Inflate the tire to 44 psi (300 kPa) to seat the tire bead to the rim, then adjust the tire pressure to specification as indicated on the tire and loading information placard, and install the valve stem cap. NOTE: Make sure the tire bead is seated on both sides of the rim uniformly.
7. Check and adjust the wheel balance, then install the wheels to the vehicle.
8. Remove the safety stands, and lower the vehicle.
9. Memorize the pressure sensor ID(s). See «RESET PROCEDURES»(/acura/mdx/i-2000-2006/remont/reset-procedures/#tire-pressure-monitor-systems__reset-procedures).

TORQUE SPECIFICATIONS

TORQUE SPECIFICATIONS

See also:
• RESET PROCEDURES
• Tire Pressure Warning Threshold Limits
• Memorizing Sensor ID (Automatically)
• Memorizing Sensor ID (Using HDS)