Mechanics

READ A DROPPING VOLTAGE FROM THE THROTTLE POSITION SENSOR

1994 Oldsmobile Bravada • 146,000 miles

What could be causing an analyzer to read a dropping voltage from the throttle position sensor as the RPM increases? I have replaced the TPS three times and the PCM yet the analyzer still continues to say the TPS is bad and shows the voltage dropping as I increase the RPM. It doesn't shift until above 2500 RPM and then shifts very hard. It also is running 200 RPM faster than normal at highway speeds even though it is in OD.
Avatar
PaulHomerJr
July 16, 2012.




What code is comming up?
AD


Docfixit
Jul 16, 2012.
22 TPS Sensor Low


Tiny
PaulHomerJr
Jul 16, 2012.
Will need a DVOM see diagrams back probe TPS connector Black lead on bottom sensor ground and middle one RED probe. Key on at idle voltage less than 1 volt(.5 v best). Then operate throttle from idle to full meter should go up steady to 4.5 V


Docfixit
Jul 16, 2012.
Opps


Docfixit
Jul 16, 2012.
It starts out at.27 and drops as the throttle is opened.


Tiny
PaulHomerJr
Jul 16, 2012.
Check reference voltag must be 5V


Docfixit
Jul 16, 2012.
Reference voltage is 5.02. Checked the ground and it's fine also. The low voltage has been the same for all 3 new TPS.


Tiny
PaulHomerJr
Jul 16, 2012.
Makes no sence if have 5v REF all TPS is a variable resistor so you say at idle.27v and as open throttl goes to zero


Docfixit
Jul 16, 2012.
My point exactly. Could this be an issue with one of the tranny sensors?


Tiny
PaulHomerJr
Jul 16, 2012.
Unplug tps use jumper wire from 5v ref and then jumper ground on bottom wire hook up meter across ground and TPS signal open throttle what does it do?


Docfixit
Jul 16, 2012.

AD