READ A DROPPING VOLTAGE FROM THE THROTTLE POSITION SENSOR

1994 Oldsmobile Bravada

Tiny

PaulHomerJr

July, 16, 2012 AT 5:57 PM

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.

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12 Answers

Tiny

Docfixit

July, 16, 2012 AT 6:01 PM

What code is comming up?

Tiny

PaulHomerJr

July, 16, 2012 AT 6:32 PM

22 TPS Sensor Low

Tiny

Docfixit

July, 16, 2012 AT 6:43 PM

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

Tiny

Docfixit

July, 16, 2012 AT 6:44 PM

Opps

Tiny

PaulHomerJr

July, 16, 2012 AT 6:54 PM

It starts out at.27 and drops as the throttle is opened.

Tiny

Docfixit

July, 16, 2012 AT 7:03 PM

Check reference voltag must be 5V

Tiny

PaulHomerJr

July, 16, 2012 AT 7:45 PM

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

Docfixit

July, 16, 2012 AT 7:52 PM

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

Tiny

PaulHomerJr

July, 16, 2012 AT 8:00 PM

My point exactly. Could this be an issue with one of the tranny sensors?

Tiny

Docfixit

July, 16, 2012 AT 8:35 PM

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?

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