[diff]

Ok. Just bought a clean 2008 SC and after 30 miles the pressure system detected low pressure and started blinking. After filling a low tire the system is still indicating a problem. (also checked the spare) Is it coincidence or is there a low tech way to reset it or a way to trouble shoot it. With all the searching i tried nothing came up on it that was in the least bit helpful except that the module is in the front headliner? Seems like there is a scanner to help test? reset it.

 

[diff]

Finally found another thread on the subject. Brutal. So will see if it clears after more driving. If not I will have to look further.

 

[anvilrob]

The TPMS module is in the REAR of your 2008 car, behind the trunk trim panel on the right side (looking toward the front of the vehicle, from behind).

Check the spare wheel tire pressure and if less than 42psi, inflate it to at least that psi.

Recheck the front tire pressures (cold) and inflate to 38 (oem door sticker will recommend 36psi).

Recheck the rear tire pressures (cold) and inflate to 44 (oem door sticker will recommend 42psi).

Discount Tire (here in the US) has a tool which can measure the signal strength of each tire valve sensor.

The valve stem sensors do lose their energy after several years so it is possible to have a wheel with good inflation yet poor signal strength.

If all the wheel sensors' signal strengths are OK, and the tire pressures indicate the correct psi on a trusted tire pressure gauge, it's probably the TPMS module that needs replacing

Rob

 

[diff]

Thank you for a very clear answer. Will report back. Makes good sense to give the tires an extra shot of air.

 

[MARK_C]

My RF tire would report low on my 06 everytime it got cold out (< about 36 degrees). The battery in the tire sensor was dying. Put new tires on back in February of this year with new sensors and the problem went away (so far). Does it tell you a specific tire, or just check tire pressure. If a single tire is to low (or to high) it will report that specific tire, if it just says check tire pressure that means there is more than one tire is out of spec, or possibly a fault in the TPMS module itself. Faults in the module are usually indicated by the little tire pressure symbol on the dash staying on after the 2 second lamp check for all the dash lights when you turn the key to position 2. If you have installed a new sensor in the spare tire and it has never been on a driving wheel, it will not be monitored by the TPMS and its sensor is rejected as a foreign sensor until it is installed on a wheel and driven on for about 15 minutes above 12 mph. Same with any new sensor going directly onto a driven wheel in the 4 corners of the car. A check tire pressure warning should reset after the car is parked for 15 minutes, and if still active will re-report the fault, otherwise it is still present in the IPC display as an existing condition. The TPMS module is in the back right corner of the truck, the RF receiver for the tire pressure sensors is mounted behind the overhead console in the roof.

 

[diff]

Thank you Mark. I came in tonite to "test drive" the 08. Warning icon still on periodically but this time it came up during the drive as to check the spare tire. So I will overfill as suggested. Will also see if light stays on in pos. 2. Hard to believe how little rust is on this beast for being in Canada but it did spend some time in florida each winter. The underside almost looks like it just rolled off the assembly line. I just hope the innards will hold up.

 

[sowr]

A couple of times my TPMS has come up with "Right Rear Tyre Pressure Low" and I know the pressure are fine. After a short while the alarm will switch to "Right Front Tyre Pressure Low", which is also fine. Then it will go away. Sometimes these monitoring systems are more trouble than they're worth. I connect my LRII diagnostic tool to see if i could turn the TPMS off - but couldn't find that option anywhere in the menus.

 

[diff]

On ours the icon now flashes for the bulb check as mentioned and then goes out. So finally that seems back to proper operation. It did take quite a while. Just in time to put on my 19's with winter tires on them and no sensors in the wheels.

 

[JerrytheK]

No help here, but I concur that TPMSs are more trouble than they are worth.

I also have a 2008 BMW X3 and 2008 328xi and the TPMSs are ALWAYS acting up.

On the RR, with snow tires mounted without TPMS sensors, I've simply put a pice of black electrical tape on the plastic dash cover to cover the 'nag' light.

 

[diff]

I found a set of very lightly used pirelli winters for our 04 20 inch rims and they are on now and I cannot believe it but they must have working sensors as no lights are on.

 

[LAJohn]

Here's a curveball question. New tires, perfect pressures and still TPMS is on/off on/off
The curveball is I brought the iLand software and one of the data streams on the ECU is for tire pressures. is showing 339/338/380/380/393 Kpa
Using an online converter that equates to an average of 48/56 psi!
Tire pressures are at 36/42 cold. I could raise to 38/44 but what's up with the ECU readings, if anyone has an in with iLand people
.

 

[MARK_C]

Kpa is an absolute pressure reading equal to -14.7 psig, or 0 psia. 1 psig is equal to 108 kpa's, and increases about 7kpa per 1 PSIG increase. Knock 14.7 psig off of each reading you got and you have the proper tire pressure reading.

 

[LAJohn]

Oh, of course, that makes sense now.... 14.7 x 4 x23.09/ 35 - 14.7 and I get 36 42 psi, what a fool I am! iland people I hope you read this Just kidding Mark, THANK you.