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I recently killed a rim on my '90 and ordered a replacement which has been installed. Now, my Service LTPWS light is coming on. How does the low tire pressure system work? Where is the sensor? Inside the rim? How do I find another sensor?
From: The land of 10,000 lakes ,Minnesota 89 coupe 6speed with 383 and 89 roadster 6speed bonestock with XXX low miles
I do know they are straped on the inside of the wheel and all 4 wheels
the sensors are the same code
When the sensor detects vibration it trips the light on the dash
Last edited by 89sleeper; Jan 1, 2006 at 07:55 PM.
'89 is somewhat different than the '90, but the problem here is probably a trouble code generated by either a missing sensor or one that isn't reporting in. Sensors generate a radio signal when vibrated sufficiently - generally above 25 mph with tire pressures greater than 25 psi - and each time you drive it, a receiver listens for a signal from each wheel - no signal the first time you drive it and it recognizes there might be a problem. The '89 doesn't have any codes - simply an idiot light. The later models have a light and a code which is usually accessible through the CCM interface.
OEM sensors run anywhere from $100 or so used to about $200 or more new. They are color coded by wheel and mounted inside the rim opposite the valve stem. If you've replaced it, you need to erase the code, so disconnecting and reconnecting the battery should do the trick or some cars provide an erase function through the dash controls.
Stupid question...Are the sensors inside of the rim covered up by the tire where you can't see them, or should you see them on the inside of the rim if you pull the wheel off?
There is a pressure sensor/transmitter inside each wheel. I think they trip at anything less than 25 PSI. The receiver is in the car. Each sensor is specific to the wheel it is on and shouldn't be moved around the car. My guess is when you got your wheel replaced they didn't put the sensor back on the rim before they mounted the tire. Your out at least 100 to 200 bucks.
Don't be "out" the bucks - go to the shop where your had the work done and get it done correctly. That's what you paid for.
The sensors strap around the rim before the tire is installed, and are hidden by the tire - they're inside. There are two different generations -early and late. I think the cutoff date is '91, but don't count on my old memory. There are definitely four units of each gen - one for each wheel. That's so you can tell by code which wheel is bad (or low). Most of them are still available from GM, but they are getting very pricey. There is a market for them used - right here on the CF, among others.
My '95 will trip a LTPWS light if the pressure gets to about 28.
Also, always check with a tire shop that they have someone who can break the bead without killing the sensors-- ExpertTire actually called me to let me know they were having a certain guy do my '95 because he had experience with the LTPWS on C4 Vettes. That was pretty cool of them.
Originally Posted by Greenvetter
There is a pressure sensor/transmitter inside each wheel. I think they trip at anything less than 25 PSI. The receiver is in the car. Each sensor is specific to the wheel it is on and shouldn't be moved around the car. My guess is when you got your wheel replaced they didn't put the sensor back on the rim before they mounted the tire. Your out at least 100 to 200 bucks.