Tire Pressure Monitoring, Part 2

BY TONY CALLAS AND TOM PRINE

I n Part 1, we examined 's 959 tire pressure monitoring system, a world first. That system, known as Reifen Druck Kontrolle (or Tire Pressure Control) was added to Rest of World 928s for 1989 and to U.S. 928s built for 1990. Despite its promise, RDK was discontin- ued after just a few years. Why? The sys- tem was expensive, and some found it more of a hassle than a help. For 2004, Porsche introduced a new, more advanced RDK system on its Cay- enne SUV. The Carrera GT also got RDK, and the system became avail- able as an option on 2005's 997-based Carrera and 987-based Boxster. RDK became standard equipment on all Por- sches built for sale in the U.S. after Sep- tember 2007. While Porsche service documentation for the 997 refers to the system as Tire Pressure Monitoring Sys- tem (TPMS), the RDK designation is used in all other models. You can, however, consider the two names interchangeable. RDK has made a comeback because While the car was stationary, we induced a Stage 2 warning—as seen on this 997 Turbo's it had to. All new vehicles weighing less central information screen. The TPMS alert symbol with its exclamation point is on, as well. than 10,000 pounds sold in the U.S. after September 1, 2007 had to have a tire As a tire loses air pressure, its rotational tages of tire pressure monitoring through pressure monitoring system. The man- diameter becomes smaller. At any given racing and had developed a system for date comes under the Transportation vehicle speed, a smaller-diameter tire will production vehicles — one more exam- Recall Enhancement, Accountability, and rotate faster than a fully inflated tire. ple of how racing improves all cars. Documentation (TREAD) Act, signed into Indirect systems identify a faster rotating This time around, Porsche has devel- law on November 1, 2000 as a direct tire over a period of time; if the trend con- oped a Direct Reading system that re- response to over 100 deaths caused by tinues, the system determines the tire sponds quickly to changes and provides roll-over accidents attributed to tread has lost pressure. If the rotational speed the driver with internal tire-pressure data separation on under-inflated tires. differential changes quickly enough, the to help maintain the best handling per- Two general types of TPM technology system decides that the tire is going flat formance while maximizing fuel econ- exist: Direct Reading and Indirect Read- and alerts the driver. Indirect TPMS sys- omy. Besides safety and performance ing. Porsche has always utilized Direct tems are less expensive to manufacture, aspects, Porsche documentation identi- Reading systems, which use a sensor in but do not respond as quickly while tend- fies extended tire life as a benefit of cor- direct contact with the air pressure inside ing to provide more false alerts. rect inflation pressure. That's because of the tire to transmit data to the car's on- When it became clear that tire pres- reducing tire air pressure by just 4.3 psi board monitoring system. sure monitoring would become manda- from the recommended inflation can Most Indirect Reading systems mon- tory in the U.S., Porsche AG was already reduce a tire's service life by 25 percent. itor the rotational speed of each tire ahead of the game. Back in the 1980s, This Tech Forum, then, will examine through the anti-lock brake (ABS) system. the company had recognized the advan- Porsche's latest take on RDK.

APRIL 2010 excellence 121 RDK for the 21st Century The wheel sensor's lithium battery has RDK System Learning The newer system utilizes advance- an expected useful life of five to ten years, When a wheel is removed for clean- ments in electronics and battery tech- with seven years considered the aver- ing, brake work, or tire installation and nologies to allow for a system commu- age. built for sale in North and then reinstalled at the same position or nication approach using high-frequency South America or Europe utilize wheel the car, the RDK system should not be radio transmissions. The primary com- sensors that transmit at a radio fre- affected. However, if a new wheel sen- ponents are four wheel-mounted sen- quency of 433 MHz, while Porsches built sor is installed or if the positions of exist- sors (one per wheel), four signal-receiv- for Asia or Africa utilize 315 MHz. Note: ing wheel sensors are moved (such as ing antennae, a system control unit, and System components with one frequency during a tire change or rotation), the sys- a pictogram display on the instrument range are not compatible with those tem must go through a multi-part identi- cluster. Each wheel-mounted sensor using the other frequency. fication and learning process. contains a pressure-and-temperature- sensing unit, control electronics, a lithium battery, and a signal-transmitting antenna attached to each wheel rim at the valve stem. One RDK signal-receiv- ing antenna is mounted in each of the four wheel housings, hidden from view by the fender liners. Each antenna sends its signals directly to the RDK control unit via a wiring harness. The pic- togram responds to output information from the control unit. Like the RDK system found in the 959 and 928, this more advanced RDK/TPMS system provides a two-stage warning. A pressure loss of 2.9-5.8 psi triggers a Stage 1 notification, where the pictogram illuminates and indicates the internal air pressure reading of the affected tire in real time. In the event of a Stage 1 warning, Porsche recom- mends drivers stop at the next suitable opportunity to correct the pressure loss. A loss greater than 5.8 psi (or a loss of more than 2.9 psi in less than one minute) triggers a Stage 2 alert, causing the pictogram to illuminate in red and indicate that the affected tire is going flat. In a Stage 2 warning, Porsche says that the driver should reduce speed and TOP LEFT: Close-up view of wheel sensor stop immediately to inspect the tire. and valve stem shows how valve stem ar.-2 Each wheel sensor transmits specific sensor attach with a thread-locking sere information to the control unit including A Valve stem mounts through wheel with the sensor's unique ID number, the cur- black gasket sealing against inside of 1.,:h rent absolute pressure in the tire, the air rim. Lower left corner of the wheel sense- temperature in the tire, the status of the has a reference to 433 MHz. TOP RIGHT: internal battery, and the status of the sen- 2008 wheel sensor, Porsche part number sor's electronics. The sensor determines 997.606.021.01; a quarter provides a sense the interval at which data will be transmit- of sensor's size. ABOVE: 433 MHz receiving ted, either in the normal or high-speed antenna next to a quarter; one is mounted mode. If tire pressure readings remain at each corner of the car and hidden by the consistent, the sensor transmits data in wheel liner. LEFT: Making a choice here the normal operating mode, measuring starts the wheel sensor learning process pressure and temperature every three seconds and transmitting the values once every 54 seconds. If the sensor measures Because each wheel sensor transmits To initiate the learning process a pressure loss of 2.9 psi in less than a its unique ID number, the RDK control make the system aware that a char minute, it starts to transmit in the high- unit will learn and remember each wheel has taken place through the on-board speed mode, where both measurements sensor's ID number and, most impor- computer's "RDK Settings" menu. Far and signal take place every tantly, which position on the car that sen- safety reasons, this menu can only 0.8 second. If the pressure loss is cor- sor ID number is mounted. This is how accessed by the driver when the vence rected and remains stable, the sensor the system can identify pressure loss at is stationary. In Cayennes, enter or re returns to the normal mode. a specific wheel. confirm wheel size; in 987/997 Boxsters.

122 excellence APRIL 2010 Carreras, or Caymans, enter or reconfirm tion Information System (PIWIS) should system's warning threshold of 5.8 psi, between winter and summer tires. be utilized. However, other code readers the display illuminates. However, the Your entry will trigger RDK's learning or diagnostic testers may provide system warning cannot be cleared when pres- mode, where it identifies specific wheel- access; when using an aftermarket code sure is corrected — even after repairing sensor ID numbers as well as where reader, check with the equipment man- or replacing the tire. each sensor is located. Failure to initiate ufacturer for its recommendations. The problem can be repaired by re- the learning phase will cause the system The most common problem with mod- setting the RDK control unit. To do so, to stop functioning. That's because RDK ern RDK occurs when a wheel sensor's briefly — with the ignition off— remove will identify that the wheel-sensor ID num- battery voltage drops below the minimum and reinstall fuse #24 on the dashboard ber(s) and/or locations have changed as threshold value necessary to continue fuse box to interrupt power. The fault soon as the vehicle is driven. The instru- operation. Another common problem is memory can now be erased and the RDK ment cluster will then display "Wheel wheel sensor electronics failure. When system should operate. If this problem Change? Check Settings." RDK remains this happens, the warning pictogram may persists frequently, replacing the original non-operational until the learning pro- illuminate with dashed lines next to the control unit (part number 955 618 160 03) cess is completed. wheels (----), indicating that no signal is with the later version (part number 955 The vehicle must be driven during the being received from the sensor. 618 160 04) will resolve this issue. two learning phases that follow. The sys- To test the wheel sensors of a Cay- Another issue with the Cayenne RDK tem receives each of the four wheel sen- enne, a technician will connect a Porsche system is its first-generation wheel sen- sors' radio-transmitted ID numbers mul- tester to the car, proceed to the TPM sec- sor electronics, which are not compati- tiple times (once every 54 seconds). As tion, and select the "Last Identification ble with second-generation units. Corro- the system continues to receive the same Received" category. In the next screen, sion at grounding connections and at four signals repeatedly, it begins to rec- he or she should choose all four options: crimped wiring locations can also create ognize these four specific ID numbers 1. Wheel Identification; 2. Wheel Elec- issues; cleaning the contacts is the solu- and then expects to receive them. Be tronics; 3. Remaining Service Life of tion. Additional issues with damage to sure that no other wheel sensors are in Identification; 4. Relative Tire Pressure wheel-sensor antennae as well as cable the car during this phase, as another sig- (actual). After hitting "Enter," the next routing have also been identified. nal may prevent the system from identi- screen should show the ID number of the fying the pertinent sensors. wheel sensor in question; however; the 997/987-specific RDK Problems Since no pressure monitoring occurs critical information is Remaining Service Some 2005-08 997 sensors provide during the first part of the learning pro- Life of Identification. The sensor is either incorrect tire-pressure values, which can cess, the RDK warning display remains "10" (in operating specification) or "NIO" vary from relatively minor to significant illuminated. Once RDK has learned (not in operating specification). Any sen- inaccuracies. To confirm proper opera- the four wheel-sensor ID numbers, the sor showing NIO must be replaced. tion, check the values on the RDK/TPMS warning display turns off and it begins All other Porsche models use another readout against those taken with a high- the next step. As the car continues to process to identify a wheel sensor's re- quality tire-pressure gauge when the be driven, RDK's control system asso- maining battery life. After connecting a tire's temperature is cold (68° F). ciates each wheel sensor ID number Porsche or other suitable testing system The right and left tires on each axle with a wheel position on the vehicle. to the vehicle, access the TPM section should be set at the same pressure. An Each wheel housing has an RDK signal- and choose the "Actual Values" option, example would be 36 psi for front tires receiving antenna and the control unit then choose "Remaining Service Life of and 44 psi for the rears. If the tire-pres- identifies the antenna at which the Battery." The system tester will then iden- sure gauge's reading indicates that both strongest signal is received for each tify the expected remaining battery life in left and right front tires have a consistent wheel-sensor ID number, then assigns months. If the sensor shows zero battery pressure reading of 36 psi while the RDK the sensor to that location. life, it must be replaced. system indicates that the left front is 36.5 Porsche says that the overall learning To avoid having a wheel sensor bat- psi while the right front reads 29 psi, a dis- process can take up to 30 minutes. Keep tery expire unexpectedly, remaining bat- crepancy obviously exists. The system in mind that, after initiation of the learn- tery life should be determined before should be checked with a PIWIS tester, ing phase, the vehicle must be moving replacing tires — as access to the wheel but it's likely that a front wheel sensor for the remainder of the process. Wheel- sensor is only possible when the tire is needs to be replaced. It should be noted sensor ID numbers and their positions on off of the wheel. Consider the miles you that absolute pressure value readings the car will remain in the system's mem- drive per month to determine the approx- between the RDK system and a tire-pres- ory until a change is detected or the sys- imate timeframe when your new tires will sure gauge may vary somewhat. tem is prompted to restart the learning be worn and require replacement. The Another issue seen on 2005-08 997s process. Each time the ignition is turned remaining sensor battery life must easily occurs when a driver goes to open the on, the system will reconfirm all data in exceed expected tire life. If not, the sen- TPMS settings menu to set tire type to its memory and, if changes are detected, sor(s) should be replaced. start the learning function and the menu RDK will stop functioning. cannot be found because the informa- Cayenne-specific RDK Problems tion window on the instrument panel has System Problems A problem relating to the 2004 (man- gone blank. This problem requires a full Any fault in the RDK system will cause ufactured in 2003) Cayenne S and reprogramming of the instrument cluster. the system to shut down and no display Cayenne Turbo is a loss of communica- will be available. In order to access and tion between the RDK control unit and Second-generation 997 RDK diagnose all issues within the RDK/TPMS the multi-function instrument cluster dis- The 2009-on 997 comes with a num- system, a Porsche Integrated Worksta- play. When pressure loss exceeds the ber of technical and system advances.

APRIL 2010 excellence 123 111117A,S One is the second-generation Tire Pres- sure Monitoring System. Pressure infor- mation is displayed much sooner after 4,1r."4- 0 V" Beaverton, Oregon www.SunsetImports.com engine start and the learning process for wheel-sensor ID numbers as well as sen- sor position has been improved. The system configuration also changed to utilize a digital central antenna Porsche Parts At Excellent Prices located in the center tunnel, between the Sunset Porsche offers all factory Porsche Parts (USA spec) at special prices for Excellence magazine readers. coolant lines. This antenna receives Samples of our pricing are listed below. signals from the wheel electronics. which are digitized at the antenna anc Factory Brake Rotors & Brake Pads sent to the control unit via two Loca 0 Cayenne S & Turbo O Boxster Boxster S Interconnect Network (LIN) bus lines. Each of the four wheel housings sti e Cayenne 6 Cylinder Front Brake Rotors — Brake Pads Front Brake Rotors - Brake Pads Brake Rotors - Brake Pads have an antenna, but these units no', send a 125 KHz triggering signal to their Front 4‘.111.1114_ N respective wheel sensor electronics a: each corner of the car. The triggering signal tells the wheel sensor that it's time to send data to the central antenna. The INNOI 997-2 TPMS control unit is designed tc

.9' • receive both 433 and 315 MHz signals. Rear However, if a replacement control unit ;s installed, the unit must be coded receive the zone-appropriate frequency North and South America and Europe retain the 433 MHz signal.

O Cayenne IS & most Turbot 2003 -2010 Cayenne le Cylinder) 2003-2010 Boxster 1907-2004 The wheel sensor includes pressure Front Rotors 955.351.401/402.51 Front Rotors 955.351.401/402.41 Front Rotors 986.351.401.05 and temperature sensors, a roll switcr Was $170.uea. Now $123.29ea. Was $153.0ea. Now $110.85ea. Was $149.0ea. Now $106.56ea. measuring and control electronics. a 955.351.939.15 Front Pad Set 955.351.939.04 Front Pad Set 986.351.939.15 Front Pad Set receiver, a transmitter, and a battery. Tr* Was $214." Now $155.°2 Was $190.56 Now $138.28 Was $145.36 Now $103.63 roll switch identifies whether the wheel Rear Rotors 955.352.401.31 Rear Rotors 955.352.401.31 Was $128. 56ea. Now $93.13ea. Was 5128.56ea. Now $93.13ea. 0 Donator S 2000-2004 turning or stationary and switches the Front Rotors 996.351.405/406.01 Rear Pad Set 955.352.939.03 Rear Pad Sat 955.352.939.03 wheel electronics off when it's stationan), Was $201.32ea. Nov $143.54ea. Was $150.56 Now $109. 8 Was 5150.5, Nov $108:* for a long period of time. Front Pad Set 996.352.949.03 Was $181. 14 Now $129.14 Each wheel sensor's electronics recetve a send request (trigger) from the contra unit to send information once per mir when the vehicle is moving. Each trio:- = - We offer our excellent prices on EVERY PORSCHE PART. sequence starts with the left front wnei. Call us with your needs. and goes clockwise around the car to left rear wheel. The use of this trigger —

* Subject to availability. Prices subject to change without notice. All orders will be charged shipping. U.S. only. All signal and sequence makes it easie. - the control unit to identify and learn orders must be shipped - no Will Call' orders. Returns most be accompanied by a return authorization number. All .. orders filled within two weeks unless back ordered from Porsche. Allow app. two weeks for delivery. USA-Spec. only. wheel sensor's ID number and post=.: Mention This Ad To Get Your EXCELLENCE Price. because each wheel sensor is respc - :-

SAVE EVEN MORE - NO SALES TAX IN OREGON ing to the control unit's request. The process of learning the ID r_ --- bers and their position on the car r- _ still take place. However, once the : Sunset Porsche type is entered in the TPMS menu ti - Beaverton, Oregon the car is driven, the learning proce s 1-800-346-0182 should take only a few minutes. E. e • Parts Hours M-F 8am-5pm Pacific Time 1=01=1 01-1 time the vehicle is unlocked, a trig email: [email protected] sequence takes place so that tire pres- sures will be available about five sec- onds after the engine is started, If ore wheel sensor fails, the system will cor- SUNSET PRICE = DEALER COST+ tinue to operate — a clear advantage over the earlier system. EVERY Audi PART, EVERY DAY The latest system generates "soft* Sunset Audi All Sunset Audi Parts Priced At Dealer Cost + 20 9/o" "hard" warnings depending on press Plus Shipping. All orders must be shipped - no 'Will Call' orders. Returns must be 1-800-346-0182 accompanied by a return authorization number. All orders filled within two weeks loss and vehicle speed. A soft warning [email protected] unless back ordered from Audi. Allow app. two weeks for delivery. USA-Spec. only.

issued if tire pressure is down 4.0-7.0 psi PATRICK MOTORSPORTS.com over a long period of time and a vehicle PORSCHE & MID-ENGINE CONVERSION SPECIALISTS speed between 0 and 100 mph is main- tained. The soft warning illuminates for Complete Concours Lightweight Flywheel & Clutch Packages Restoration... approximately 10 seconds in white text Race Proven Exclusive! when the ignition is turned on or off. A 5.50 Inch Single or Multi Disc Package For 901 Trans. Race Winning hard (or puncture) warning comes when From $1545.00 Preperation! tire pressure loss exceeds 7.0 psi for 4. Available Now! "LARGEST STOCKING DISTRIBUTOR Proud to Feature: speeds up to 100 mph, or if pressure loss OF PORSCHE & IMPORT CLUTCHES" exceeds 6.0 psi at speeds over 100 mph All Models In Stock Testing & TunIng Services and/or if tire pressure is decreasing faster from 356 to 997 Transmission Sales, Service & Conversions than 3.0 psi per minute. The hard warn- G50 Short Bell Housing ing display illuminates in red whenever 911 & 914 - 6 Product Specials Conversions the pressure losses or speed criteria is • 911 & 914 FUEL SAFE' Fuel Cells, from $ 1975 exceeded; this display will remain on until • 914-6 Chromoly Bulk Head Engine Mount $ 459 • 914 Rear Sport Coil-Over Shock Kit $ 595 the pressure is corrected. • 914/911 Front Suspen. DELRIN' 1 Bushings $ 98 • 914 Rear Trailing Arm DELRIN' Bushings $ 88 Conclusion • 914 Rear Trailing Arm Box Kit $ 89 • 914 Rear Chassis Stiffening Kit $ 149 Whether your Porsche has a tire pres- • 914-6 Engine Sheet Metal Set $ 445 • 901, 915, 930, G50, G-50/50 sure monitoring system or not, check tire • 911 & 914-6 Front Oil Cooler Kits, from $ 595 • Fu! Service & Race Preparation inflation values at least once a month and • 914-6 Conversion Oil Tanks, Aluminum $ 795 • Mid Engine Transaxle Specialists • 914-6 Stainless Steel Headers with Heat $ 1975 • Huge Inventory/ New & Used correct them as needed. If your RDK/TPMS • 911 & 914 Solid Engine Mount Set $ 98 • Limited-Slip & TQ Biasing Diffs system is not working properly, find out • 914/901 Solid Transmission Mount Set $ 98 • CENTERFORCE' Clutch Kits why and get it corrected — as this tech- $ 1975 • 915 WEVO Tail Shift Transmission Kit • RSR Ring & Pinion / Gear Sets nology can pay real dividends. IP • 914 GT LW Body Pannels In Stock! • Shifter System & Components CS, [mil &WM:1M, Also Featuring: Some information in this article is copy- sort CWT Industries otaast SM HS Computerized Balancing Systems righted by and used with the permission ecopy, xopa Par xi., (.6n. • agNsw move of Porsche Cars North America. Photos Phone: 602-244-0911 Fax: 602-244-0900 by Tom Prine. Have a tech question? Write Phoenix, Arizona, 85U34 - USA i All Major Credil Colds AoL.epled Worldwide Freight us at: techforum Q excellence-mag.com

©2010 Porsche Cars North America. Porsche recommends belt usage and observance of all traffic laws at all times. Plus freight, and remember we don't charge a "handling fee," while supplies last. PLEASE BE SURE TO CHECK OUT OUR MAIL ORDER PRICING FOR YOUR GENUINE PORSCHE PARTS.

WATCH SALE* Retail Special Retail Special Retail Special Womens Panamera Chrono 911 Turbo Sport Chrono Boxster Sport Classic Chrono WAP-070-006-0A 675.00 545.00 WAP-070-002-19 649.00 525.00 WAP-070-011-19 649.00 525.00 Panamera Swarovski Panamera Turbo Chrono GT-3 Sport Classic Chrono WAP-070-007-0A 389.00 315.00 WAP-070-005-0A 719.00 580.00 WAP-070-008-19 699.00 565.00 Womens Panamera Chrono Ltd. Edition 911 Sport Classic Chrono WAP-070-008-0A 675.00 545.00 WAP-070-005-19 649.00 525.00

Hennessy Porsche NORTH ATLANTA Porsche Perfect Service Award Winner 770-643-6100, 888-416-7053 990 Mansell Road, Roswell, GA 30076 GA 400 to Mansell Rd., One Mile West HennessyPorsche.com P =

126 excellence APRIL 2010