The Throttle Position Switch on my 2001 Prizm (110,000K miles) shows 10% on my scan tool when the throttle plate is closed. As far as I can tell there are no opens or shorts and the voltage and resistance change smoothly (no dead spots) as I advance the throttle manually (engine off in run). My Haynes book doesn't help much. With the (large) resistance range it quotes I should be OK.
Is this normal/acceptable for this vehicle? All other cars that I've scanned show 0% when the throttle is closed. The manual says it's not adjustable and that the computer self-calibrates at idle w.r.t. the reference voltage.
I ask because the long term trim is more than 10% rich. I noticed this TPS quirk when diagnosing my O2 sensors. I periodically get a MIL light with a 420 code. It's the only one and I have no overt drivability problems other than fuel efficiency. I get ~26 mpg in short hops and haven't been on any long trips lately.
I'll find/fix whatever's wrong with the CAT/O2 system,
but I'd like to resolve this question first.
Thanx
Is this normal/acceptable for this vehicle? All other cars that I've scanned show 0% when the throttle is closed. The manual says it's not adjustable and that the computer self-calibrates at idle w.r.t. the reference voltage.
I ask because the long term trim is more than 10% rich. I noticed this TPS quirk when diagnosing my O2 sensors. I periodically get a MIL light with a 420 code. It's the only one and I have no overt drivability problems other than fuel efficiency. I get ~26 mpg in short hops and haven't been on any long trips lately.
I'll find/fix whatever's wrong with the CAT/O2 system,
but I'd like to resolve this question first.
Thanx
Oct 15, 2009 at 2:57 PM
