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Code 21, surging
Topic Started: Oct 28 2012, 07:42 PM (1,237 Views)
Shinrin
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So, on the way home from work my check engine light started flickering. On my last mile stretch, if i let off the gas in gear the engine would surge and i started to lose speed fast.

Checked the code when I got in, and its code 21 - TP Sensor Circuit Signal Voltage High

So I suppose my TPS is giving me problems? What do you guys suggest checking?
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busteriver
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[ *  *  *  *  * ]
Code 21 - Throttle Position Sensor (TPS) Circuit (Signal Voltage High)



Circuit Description

The Throttle Position Sensor (TPS) provides a voltage signal that changes relative to the throttle blade. Signal voltage will vary from about 0.5 at idle to about 5 volts at wide open throttle.

The TPS signal is one of the most important inputs used by the ECM for fuel control and for most of the ECM control inputs.

Problem Description:

Code 21 will set if:

Engine running less than 1600.
TPS signal voltage is greater than 2.5 volts.
All conditions met for 2 seconds.
MAP less than 70 kPa.
With throttle closed the TPS should read less than 1.25 volts. If it doesn't replace TPS.

Diagnostic Aids:

A Scantool reads throttle position in volts. It should read less than 1.25 volts with throttle closed and ignition on or at idle. Voltage should increase at a steady rate as throttle is moved toward WOT.

An open in CKT 452 will result in a Code 21.

"Scan" Diagnostics:

Throttle closed.

Does scantool display TPS over 2.5 volts?

NO YES
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Woodie
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Bad sensor ground
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Shinrin
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I got it figured out, probably the simplest thing it could be. My clip holding the wire onto the tps is missing, and the wire had come loose. It was just barely making contact.
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