TPMS reading low(?)

**wvstar** · 11-04-10, 06:20 AM

My TPMS sensors showed a 29 PSI reading for both my front tires the other day (cold) and bumped up to like 31 after a short drive. I stopped to add air but the gauge showed the tires had like 35 lbs. (Hmmm?) Which do I believe? I figured add a little air and see what happens. I bumped the (air gauge) reading up to just under 40 lbs to see how the TPMS sensors responded. They never changed. Also, each time I drive the car, they report 29 PSI and bump up to 31 later.

Been using my hand-held gauge. Do the TPMS sensors normally fail to read properly when their batteries going low / bad? Or do they just quit working?

Also, how does the dash/display react when a sensor goes bad or you do not have the sensors (say on wheels w/o TPMS installed)? I know you would not get readings (of course)...but does the system beep / alarm ,etc or anything else annoying?

As you can tell...I've only had my Vette a few months now so not real familiar with a lot of the workings, etc.

Definitely looking to upgrade wheels over the winter. Am running stock steelies (17" & 18") and would like to bump up to maybe 18" - 19" setup. Would I be better off buying new sensors or having my existing sensors installed on the new wheels (i.e. if I can replace the batteries and get them working correctly)? Sounds like maybe my sensors are going to crap anyway.

Thanks for any input!

**napacruzerC5** · 11-06-10, 10:27 PM

Depending on when your '99 first hit the road, your TPMS sensors could be over 12 years old. I can't rely on my mine on my '01. Usually use my manual gauge now. The problem with replacing yours is the 1997-2000 models cost over twice as much as 2001-2004 and you can't use the newer model on your 1999. Looks like its time to bite the bullet and get new ones. There is someone (you'll have to search the forums) who will rebuild your old sensors with new batteries but doesn't sound like a DIY project.

**wvstar** · 11-07-10, 08:14 AM

Thanks for the reply.

Can someone tell me how the dash/display reacts when you do not run sensors at all? Just no readings (?) or is there some annoying alarm?

Having the dash info is nice...but I really have no issues with using a manual gauge if the dashboard does not alarm/tone when it does not find sensors. Especially when I upgrade wheels/tires.

**redvett** · 11-07-10, 01:44 PM

Never use the TPMS to set tire pressure only use a good handheld Gauge and check only when tires are cold. Driving just a little ways will increase tire pressure.

**napacruzerC5** · 11-07-10, 03:33 PM

Originally Posted by wvstar

Thanks for the reply.

Can someone tell me how the dash/display reacts when you do not run sensors at all? Just no readings (?) or is there some annoying alarm?

Having the dash info is nice...but I really have no issues with using a manual gauge if the dashboard does not alarm/tone when it does not find sensors. Especially when I upgrade wheels/tires.

The DIC will probably show:

LF xxx RF xxx

At least that's what shows on mine when it can't read the TPMS.

**redvett** · 11-07-10, 04:23 PM

One light will light for low PSI and another will light up for TPMS problem evertime you start up the car.

**wvstar** · 11-08-10, 01:35 PM

Originally Posted by redvett

One light will light for low PSI and another will light up for TPMS problem evertime you start up the car.

I've not seen any lights as yet...and the TPMS sensors do not show any reading at all until after the car has moved forward several feet. The DIC displays "LF RF " and "LR RR " until they report - but no lights at all (?). Course the sensors are there.

Sounds like it's worth their cost to avoid the annoyance.