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Car Forum / Nissan / Nissan Cars / March 2007Low Tire Pressure Warning
I have a brand new (bought in January) 2007 Versa. When I got it the tire pressure on all 4 was set at 40 PSI. I have left it at that value since the dealer/factory set it. Last Friday I took a short road trip, less than a hundred miles. About 2/3 of the way there the Low Tire Pressure light came on. I immediately pulled over and checked the tires. None seemed to be low, so I got out the pressure gauge and checked them. I found that the 2 front tires were up around 44 or 45 PSI. The rear tires were still around 40. I reduced the pressure on the front tires to 40 and started on down the road. The light went out and has stayed out ever since. I have made that trip twice before since I got the car but this is the first time when the temperature has been in the 70s. The last 2 times it was much colder. Does any body know what could have caused that? Does the system check more for a difference in pressure, rather than an actual pressure? Thanks for any help Bill Gill Nissan says in the car handbook that tire pressures should be set to 32 psi. 40 psi is a bit high and will give you a rough ride and not too good handling in wet weather. I have a brand new (bought in January) 2007 Versa. When I got it the tire pressure on all 4 was set at 40 PSI. I have left it at that value since the dealer/factory set it. Last Friday I took a short road trip, less than a hundred miles. About 2/3 of the way there the Low Tire Pressure light came on. I immediately pulled over and checked the tires. None seemed to be low, so I got out the pressure gauge and checked them. I found that the 2 front tires were up around 44 or 45 PSI. The rear tires were still around 40. I reduced the pressure on the front tires to 40 and started on down the road. The light went out and has stayed out ever since. I have made that trip twice before since I got the car but this is the first time when the temperature has been in the 70s. The last 2 times it was much colder. Does any body know what could have caused that? Does the system check more for a difference in pressure, rather than an actual pressure? Thanks for any help Bill Gill Normally these systems use the difference in the rotation speed to sense the low pressure in one of the tires. Not sure about this one in particular though. > I have a brand new (bought in January) 2007 Versa. When I got it the > tire pressure on all 4 was set at 40 PSI. [quoted text clipped - 18 lines] > > Bill Gill "Difference in rotation speed"? Want to think about that a little? According to the little bit of physics I've learned your response is unhelpful and unaccurate. If you take your Nissan to a shop with the right reader the pressure in each tire down to one decimal point can be read. The reading is very accurate, too, BTW. The problem is in one or more of the tire sensors or in the reader/indicator module which triggers the instrument panel indicator. Typically shops don't like to spend much time on diagnosing LTP warning malfunctions. My local dealer's service manager stated that he wished they had never put the damn things on the cars. According to him about 99% of the warnings were due to owner inattention to TP or to improper pressure adjusted by owners. Last week, after the third time in the shop for my low TP indicator malfunction they reset the receiver/indicator module instead of simply adding air. Hopefully this will do the trick. Butch > Normally these systems use the difference in the rotation speed to sense > the low pressure in one of the tires. Not sure about this one in [quoted text clipped - 22 lines] >> >> Bill Gill The company I work for manufactures tire pressure monitoring sensors and receivers (among other things). I thought I would give you a brief explanation of how they work. The sensor is banded to the wheel inside the tire. There are different flavours of sensors, but usually they are either continuously transmitting or they have a switch inside that transmits only when the wheel is turning. These sensors measure actual pressure inside the tire. They transmit via RF to the receiver inside the car. The receiver is the "brains" of the system. It will throw a warning when a sensor fails or when a tire pressure is a certain percentage different from the others and/or it's initial value. The sensors have batteries inside them and will last typically longer than the life of the tire. DS > "Difference in rotation speed"? Want to think about that a little? > According to the little bit of physics I've learned your response is [quoted text clipped - 44 lines] >>> >>> Bill Gill > The company I work for manufactures tire pressure monitoring sensors and > receivers (among other things). I thought I would give you a brief [quoted text clipped - 11 lines] > > DS I have looked the tires over, and looked on the web to try to find out about the way the system works. I found out that there are some that do work by difference in rotational speed. At least some of these tap into the ABS wheel speed sensor to check the wheel speed. If one is significantly different from the others it triggers the alarm. There are several systems that use a sensor inside the tire to measure the pressure. They typically transmit the pressure to an on-board sensor for processing. This is very similar to the set up described by DS. It appears that the one used by Nissan is one that is built into the valve stem. The sensor is actually located inside of the tire. I never did find anything that said exactly how the Nissan system works, other than the integral sensor. But I found at least one car that did have an over pressure warning included. It was set to trigger at 39 PSI. That would be in line with my having gotten a warning when my pressure gauge said the pressure was 44 or 45 PSI. Especially if my gauge happens to read high. Some Nissan models do have the complete read-out on the dash board display. The Versa doesn't, just the pressure alarm. I plan on getting a new, and hopefully more accurate, pressure gauge. That should keep me better informed on what is going on with my tires. Thanks for all the good answers. Bill Gill Yes, difference in the rotation speed: http://www.nhtsa.dot.gov/cars/rules/rulings/TirePressure/LTPW2.html I made clear " Not sure about this one in particular though. " Whose response is unhelpful and INaccurate? Through the years I have come to realize that people who know the most are mostly humble. > "Difference in rotation speed"? Want to think about that a little? > According to the little bit of physics I've learned your response is [quoted text clipped - 45 lines] >>> >>>Bill Gill Interesting link. Did you not say " Normally these systems use the difference in the rotation speed to sense the low pressure in one of the tires?" Does "normally" not indicate that it is the norm? Does the norm not indicate the usual? Did you not notice in the discussion of the ABS based alternative that it does not work well enough at this time as it is too inaccurate to detect pressure losses of at best 20% and more likely 30% and that it has a set of additional proplems making it an unsatisfactory system? For example it will not work at speeds over 70 MPH. In order for the rotational speed of a tire to significantly change due to pressure loss the loss must be large. After all, the tire circumference determines the rotational speed at a given speed, eh? Thank you. Butch > Yes, difference in the rotation speed: > http://www.nhtsa.dot.gov/cars/rules/rulings/TirePressure/LTPW2.html [quoted text clipped - 55 lines] >>>> >>>>Bill Gill > Normally these systems use the difference in the rotation speed to > sense the low pressure in one of the tires. Not sure about this one > in particular though. The Nissan system uses transmitters in the tire. The systems that work on variations in tire rotation aren't very accurate. I had a 2001 Mustang with ABS and if you had a tire that was significantly under inflated, it would cause the ABS system malfunction indicator light to come on. I had a tire with a slow leak and I could count on the ABS light alerting me when it got significantly lower than normal. I know this was not a smart thing to do (ride around with a tire that had a slow leak). I had ordered new replacement tires and was just waiting for them to arrive. GM cars that used the ABS systems to detect under inflation required a significant learning period. They do work, but I am not sure they work well enough to improve safety. I also think system that use ABS sensor require four channel ABS (a sensor on every wheel) instead of the three channel systems used on many rear wheel drive light trucks. Ed > I have a brand new (bought in January) 2007 Versa. When I got it the > tire pressure on all 4 was set at 40 PSI. [quoted text clipped - 18 lines] > > Bill Gill You might want to try a different gauge. The cheap ones are notoriously inaccurate. >I have a brand new (bought in January) 2007 Versa. When I got it the >tire pressure on all 4 was set at 40 PSI. > I have left it at that value since the dealer/factory set it. 40 psi is too high. Check the placard for the correct pressure. Tire pressures are often set higher than recommended for shipping. The dealership should have set the tires to the correct pressure during the pre-delivery inspection process. The pressure will increase as you drive the car, so it is not surprising that the pressure was higher when you checked the tires in the middle of a trip. The pressures are to be set when the tires are cold. You also need to check your tire pressures at least monthly. As the outside average temperature cahnges with the season, your tire pressure will fluctuate as well. Don't put too much faith in the monitoring system. I have a 2006 Frontier with the system. Like you mine came on unexpectedly. I never did find a problem. I believe in my case the system was triggered when we had an exceptionally cold morning. > Last Friday I took a short road trip, less than a hundred miles. > About 2/3 of the way there the Low Tire Pressure light came on. I [quoted text clipped - 4 lines] > and started on down the road. The light went out and has stayed out > ever since. In my opinion, altering the pressure once the tires were hot was a mistake. The front and rear tires ae loaded differently, so it is entirely possible that they will have different "hot" pressures even if they start out with the same "cold" pressure. You should set your pressures to the manufacturer's recommended pressure when the tires are cold. > I have made that trip twice before since I got the car but this is > the first time when the temperature has been in the 70s. The last 2 > times it was much colder. The system only checkes the pressures once your speed exceeds 16 MPH. I would not think a higer external emeprature would ahve triggered the system since this should have raised the pressure in the tires. > Does any body know what could have caused that? Does the system > check more for a difference in pressure, rather than an actual > pressure? Not sure. I belieev it monitors changes in pressure, not the differential. In your case I think it reacted to the rear tires being lower. Did you check your owner's guide? THe following comes form theon line version of the manual: Low tire pressure warning light (if so equipped) Your vehicle is equipped with a Tire Pressure Monitoring System (TPMS) that monitors the tire pressure of all tires except the spare. The low tire pressure warning light warns of low tire pressure or indicates that the TPMS is not functioning properly. After the ignition switch is turned ON, this light illuminates for about 1 second and turns off. Low tire pressure warning: If the vehicle is being driven with low tire pressure, the warning light will illuminate. When the low tire pressure warning light illuminates, you should stop and adjust the tire pressure to the recommended COLD tire pressure shown on the Tire and Loading Information label. The low tire pressure warning light does not automatically turn off when the tire pressure is adjusted. After the tire is inflated to the recommended pressure, the vehicle must be driven over 16 MPH (25 km/h) to activate the TPMS and turn off the low tire pressure warning light. Use a tire pressure gauge to adjust tire pressure to the recommended pressure. For additional information, see "Tire pressure monitoring system (TPMS)" in the "Starting and driving" section. TPMS malfunction: If the TPMS is not functioning properly, the low tire pressure warning light will flash for approximately 1 minute when the ignition switch is turned ON. The light will remain on after the 1 minute. Have the system checked by a NISSAN dealer. For additional information, see "Tire pressure monitoring system (TPMS)" in the "Starting and driving" section. WARNING * If the light does not illuminate with the ignition switch turned ON, have the vehicle checked by a NISSAN dealer as soon as possible. * If the light illuminates while driving, avoid sudden steering maneuvers or abrupt braking, reduce vehicle speed, pull off the road to a safe location and stop the vehicle as soon as possible. Serious vehicle damage could occur and may lead to an accident and could result in serious personal injury. Check the tire pressure for all four tires. Adjust the tire pressure to the recommended COLD tire pressure shown on the Tire and Loading Information label to turn the low tire pressure warning light OFF. If the light still illuminates while driving after adjusting the tire pressure, a tire may be flat. If you have a flat tire, replace it with a spare tire as soon as possible. * When a spare tire is mounted or a wheel is replaced, tire pressure will not be indicated, the TPMS will not function and the low tire pressure warning light will flash for approximately 1 minute. The light will remain on after 1 minute. Contact your NISSAN dealer as soon as possible for tire replacement and/or system resetting. * Replacing tires with those not originally specified by NISSAN could affect the proper operation of the TPMS. CAUTION * The TPMS is not a substitute for the regular tire pressure check. Be sure to check the tire pressure regularly. * If the vehicle is being driven at speeds of less than 16 MPH (25 km/h), the TPMS may not operate correctly. * Be sure to install the specified size of tires to the 4 wheels correctly. ------- SYSTEM (TPMS) (if so equipped) Each tire, including the spare (if provided), should be checked monthly when cold and inflated to the inflation pressure recommended by the vehicle manufacturer on the vehicle placard or tire inflation pressure label. (If your vehicle has tires of a different size than the size indicated on the vehicle placard or tire inflation pressure label, you should determine the proper tire inflation pressure for those tires.) As an added safety feature, your vehicle has been equipped with a tire pressure monitoring system (TPMS) that illuminates a low tire pressure telltale when one or more of your tires is significantly under-inflated. Accordingly, when the low tire pressure telltale illuminates, you should stop and check your tires as soon as possible, and inflate them to the proper pressure. Driving on a significantly under-inflated tire causes the tire to overheat and can lead to tire failure. Under-inflation also reduces fuel efficiency and tire tread life, and may affect the vehicle's handling and stopping ability. Please note that the TPMS is not a substitute for proper tire maintenance, and it is the driver's responsibility to maintain correct tire pressure, even if under-inflation has not reached the level to trigger illumination of the TPMS low tire pressure telltale. Your vehicle has also been equipped with a TPMS malfunction indicator to indicate when the system is not operating properly. The TPMS malfunction indicator is combined with the low tire pressure telltale. When the system detects a malfunction, the telltale will flash for approximately one minute and then remain continuously illuminated. This sequence will continue upon subsequent vehicle start-ups as long as the malfunction exists. When the malfunction indicator is illuminated, the system may not be able to detect or signal low tire pressure as intended. TPMS malfunctions may occur for a variety of reasons, including the installation of replacement or alternate tires or wheels on the vehicle that prevent the TPMS from functioning properly. Always check the TPMS malfunction telltale after replacing one or more tires or wheels on your vehicle to ensure that the replacement or alternate tires and wheels allow the TPMS to continue to function properly. Additional information: * The TPMS does not monitor the tire pressure of the spare tire. * The TPMS will activate only when the vehicle is driven at speeds above 16 MPH (25 km/h). Also, this system may not detect a sudden drop in tire pressure (for example a flat tire while driving). * The low tire pressure warning light does not automatically turn off when the tire pressure is adjusted. After the tire is inflated to the recommended pressure, the vehicle must be driven at speeds above 16 MPH (25 km/h) to activate the TPMS and turn off the low tire pressure warning light. Use a tire pressure gauge to check the tire pressure. * Tire pressure rises and falls depending on the heat caused by the vehicle's operation and the outside temperature. Low outside temperature can lower the temperature of the air inside the tire which can cause a lower tire inflation pressure. This may cause the low tire pressure warning light to illuminate. If the warning light illuminates in low ambient temperature, check the tire pressure for all four tires. For additional information, see "Low tire pressure warning light" in the "Instruments and controls" section and "Tire pressure monitoring system (TPMS)" in the "In case of emergency" section. WARNING * If the low tire pressure warning light illuminates while driving, avoid sudden steering maneuvers or abrupt braking, reduce vehicle speed, pull off the road to a safe location and stop the vehicle as soon as possible. Serious vehicle damage could occur and may lead to an accident and could result in serious personal injury. Check the tire pressure for all four tires. Adjust the tire pressure to the recommended COLD tire pressure shown on the Tire and Loading Information label to turn the low tire pressure warning light OFF. If you have a flat tire, replace it with a spare tire as soon as possible. (See "Flat tire" in the "In case of emergency" section for changing a flat tire.) * When a spare tire is mounted or a wheel is replaced, the TPMS will not function and the low tire pressure warning light will flash for approximately 1 minute. The light will remain on after 1 minute. Contact your NISSAN dealer as soon as possible for tire replacement and/or system resetting. * Replacing tires with those not originally specified by NISSAN could affect the proper operation of the TPMS. * Do not inject any tire liquid or aerosol tire sealant into the tires, as this may cause a malfunction of the tire pressure sensors. CAUTION Do not place metalized film or any metal parts (antenna, etc.) on the windows. This may cause poor reception of the signals from the tire pressure sensors, and the TPMS will not function properly. FCC Notice: Changes or modifications not expressly approved by the party responsible for compliance could void the user.s authority to operate the equipment. This device complies with Part 15 of the FCC Rules and RSS-210 of Industry Canada. Operation is subject to the following two conditions: (1) This device may not cause harmful interference, and (2) this device must accept any interference received, including interference that may cause undesired operation of the device. -------- TIRE PRESSURE MONITORING SYSTEM (TPMS) (if so equipped) This vehicle is equipped with the tire pressure monitoring system (TPMS). It monitors tire pressure of all tires except the spare. When the low tire pressure warning light is lit, one or more of your tires is significantly under-inflated. If the vehicle is being driven with low tire pressure, the TPMS will activate and warn you of it by the low tire pressure warning light. This system will activate only when the vehicle is driven at speeds above 16 MPH (25 km/h). For more details, refer to "Warning/indicator lights and audible reminders" in the "Instruments and controls" section, and "Tire pressure monitoring system (TPMS)" in the "Starting and driving" section. > Thanks for any help > > Bill Gill |
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