Top News

AUTO ADVICE: Tire pressure is fine, but the light stays on

What do you do when your tires are properly pressurized but the indicator light insists on staying lit?
What do you do when your tires are properly pressurized but the indicator light insists on staying lit? - 123RF Stock Photo


My father has a 2002 Hyundai XG350. It will start, go, stop, start again, maybe for days and maybe only once! He jumps it and away it goes, maybe for days and maybe tomorrow! When it’s dead it’s completely dead. No lights, no horn, no nothing. He had all the usual suspects checked: battery, spark plugs etc. Any thoughts? He reads the paper every day so he will see your answer. Thanks.



Start by having the battery checked again and check the connections between the battery cables, the vehicle grounds and the starter. I have seen batteries that tested good a couple times but failed completely when tested a third time. This happens because of an intermittent connection between cells inside the battery. Also, clean and tighten cable connections before going on to other tests.

It is possible that a light in staying on in the vehicle and draining the battery. Glove box, trunk and underhood lights can drain a battery overnight if the battery isn’t fully charged and may not be easily noticed. You can test for electrical drains with an ammeter but a visual check may spot the problem first.

Finally, one of the vehicle computers may not be powering down properly when you shut the vehicle off. This can drain the battery in a few hours, depending on what is still powered up. Test for electrical drains by placing an ammeter in series with one of the battery cables but be sure to have all electrical devices on the car turned off first or you will damage the ammeter. 

The drain on the battery should be less than 50 milliamps and ideally less than 25 milliamps. If the electrical drain is high, pull one fuse at a time till the drain drops (do not reinstall each fuse).  When the drain drops, this is the circuit that is causing the problem and you can check the wiring diagram to locate what is on that electrical circuit. 

To access fuse boxes inside the car, prepare the car before connecting the ammeter by opening the door and then manually latching the door latch or taping the door jamb switch so the interior lights are not on. Then you can leave the door open to remove fuses inside the car if necessary. 


We have a 2010 Toyota Corolla with 66,000 km. We have the winter tires mounted on separate rims. After driving for about 20 minutes the tire pressure monitor light comes on despite the fact that the pressure in all four tires is fine. After a two-plus hour of rest the indicator light is off until driving for another 20 minutes. This has been occurring through two sets of winter tires. Summer tires are fine. A mechanic told us that to find the problem would be time consuming and therefore expensive. Any ideas on how to isolate the problem tire? 


The first thing to check is the pressure in the spare tire. The Toyota system monitors all the tires including the spare with the Tire Pressure Monitoring System (TPMS), and this tire is often overlooked.

Whenever you replace a sensor, module or install a second set of wheels such as winter tires, the new IDs for the sensors must be programmed into the system through the OBD-II connection. The ID numbers can be found on the sensors. If you didn’t record the sensor numbers, TPMS tools can collect the ID number by either capturing the signal from a sensor or by activating the sensor by letting pressure out of the tire so that the pressure drops more than six PSI within 30 seconds. This also tests the output of the sensors. 

If tire pressure is good and the sensors have been programmed into the system, then try resetting the TPMS. With the ignition key on but engine not running, hold the reset button (either on the dash, in the glove box or beneath the steering column) for several seconds until the tire pressure warning light flashes at least three times. Wait for a minimum of three minutes while the receiver gets signals from the tire pressure sensors and then turn the key off for a couple minutes. 

You will likely have to drive the vehicle at speeds of 30 kph for more than an hour before the system completely initializes again. Rotating tires or switching between summer and winter tires and wheels will require the system to be reset again so the receiver is getting the correct signals from the sensors.


Did this story inform or enhance your perspective on this subject?
1 being least likely, and 10 being most likely

Recent Stories