Tire Pressure Gauge
Thread Starter
Cruising
Joined: May 2007
Posts: 10
Likes: 0
Tire Pressure Gauge
Hi. I own a 1999 C5 and all 4 tire pressure gauges are off -6 or -7. I tried calibrating through the DIC using a magnet around the inflation stem as per some of the postings I found, but after the car recognizes the gauges I still get the same readings.
Are there any otehr options?
Are there any otehr options?
Safety Car
Joined: Aug 2000
Posts: 4,933
Likes: 30
From: San Rafael CA
Hi. I own a 1999 C5 and all 4 tire pressure gauges are off -6 or -7. I tried calibrating through the DIC using a magnet around the inflation stem as per some of the postings I found, but after the car recognizes the gauges I still get the same readings.
Are there any otehr options?
Are there any otehr options?
Buy a new tire pressure gauge. Your gauge is wrong .... not the four sensors .....
Safety Car
Joined: Jan 2001
Posts: 4,386
Likes: 689
From: Boise ID
The relearn procedure just teaches the sensor location but in no way is it a calibration. My old sensors were a good 2 psi low compared to two different digital gauges. My new sensors are pretty much on the money.
Safety Car
Joined: Aug 2000
Posts: 4,933
Likes: 30
From: San Rafael CA
.... the re-learn is a position issue ... there is no calibration.Note that these sensors, in conjunction with the RFA, are quite accurate, even adjusting for changes in altitude .... which MIGHT explain a one or 2 pound difference between the sensors and a couple of digital gauges.
When you first start the vehicle the RFA reads the BARO (barometric pressure) from the PCM (which gets it from the MAP sensor prior to engine turnover). The TPMS are sending the "absolute" pressure they are reading inside the tire to the RFA ... and the RFA deducts BARO to then get "tire pressure".
So let's say you are sitting at sea level and you start the car. The BARO is 14.7 PSI (let's make it 15 PSI just to keep this simple ...) and the TPMS are reporting absolute tire pressure as 45 PSI. Your displayed tire pressure will be (45 - 15) = 30 PSI
Now we have driven up a mountain, turn off the car, and start it up later. The absolute pressure inside the tires hasn't changed (let's assume same temperature, and that the tire is so "stiff" it can't "grow" with the lower external pressure) but the BARO is now lower because of the higher altitude (say 13 PSI) so on start-up the displayed tire pressure will be (45 - 13) = 32 PSI.
Neat, huh ????
Tech Contributor
Joined: Oct 1999
Posts: 41,044
Likes: 9,808
From: Charlotte, NC (formerly Endicott, NY)
They meant you should buy a new hand held gauge. The gauges at the auto parts stores are not calibrated either. It is possible to buy 20 gauges and get 20 different readings when measuring the same tire at the same time. I have a large dial gauge that I use for the track. When I set a tire at 25 lbs I don't know for sure that is 25 lbs but I do know a 25 reading on that gauge gets me the performance I want.
To replace the sensors you will have to buy another set (in the range of $85-100 each depending on year) and then have the tires broken down by a shop so the sensors can be replaced. A lot of money just to make your sensors read the same as a cheap gauge and there is a high likelihood that it won't work anyway.
Bill
To replace the sensors you will have to buy another set (in the range of $85-100 each depending on year) and then have the tires broken down by a shop so the sensors can be replaced. A lot of money just to make your sensors read the same as a cheap gauge and there is a high likelihood that it won't work anyway.
Bill
Burning Brakes
Joined: Mar 2006
Posts: 1,195
Likes: 25
From: Tacoma WA
They meant you should buy a new hand held gauge. The gauges at the auto parts stores are not calibrated either. It is possible to buy 20 gauges and get 20 different readings when measuring the same tire at the same time. I have a large dial gauge that I use for the track. When I set a tire at 25 lbs I don't know for sure that is 25 lbs but I do know a 25 reading on that gauge gets me the performance I want.
To replace the sensors you will have to buy another set (in the range of $85-100 each depending on year) and then have the tires broken down by a shop so the sensors can be replaced. A lot of money just to make your sensors read the same as a cheap gauge and there is a high likelihood that it won't work anyway.
Bill
To replace the sensors you will have to buy another set (in the range of $85-100 each depending on year) and then have the tires broken down by a shop so the sensors can be replaced. A lot of money just to make your sensors read the same as a cheap gauge and there is a high likelihood that it won't work anyway.
Bill
As long as it's consistent it doesn't have to be accurate. Just learn how much it's off, and do the math from there.
-Dan
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Safety Car
Joined: Mar 2000
Posts: 4,077
Likes: 27
From: Northeast South Dakota
Yeah, your handheld tire pressure gauge is off. But it doesn't really matter, just get used to how far off it is and fill the tire up to what the dash says. You don't really need to know exactly how much air is in the tires, just when one starts to drop which will show you a leak.
-Justin
-Justin
