Cliff: Created page with "'''Throttle position sensor''' refers to the throttle-position sensor used by the Pontiac Fiero ECM. The throttle position sensor tells the ECM how far the throttle is opened. The ECM uses this information for fuel control, acceleration enrichment, idle behavior, deceleration behavior, and diagnostic trouble code decisions. == Overview == The throttle position sensor, often abbreviated as TPS, is mounted on the throttle body and is connected to the throttle sh..."

2026-07-06T20:29:04Z

Created page with "'''Throttle position sensor''' refers to the throttle-position sensor used by the Pontiac Fiero ECM. The throttle position sensor tells the ECM how far the throttle is opened. The ECM uses this information for fuel control, acceleration enrichment, idle behavior, deceleration behavior, and diagnostic trouble code decisions. == Overview == The throttle position sensor, often abbreviated as TPS, is mounted on the throttle body and is connected to the throttle sh..."

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'''Throttle position sensor''' refers to the throttle-position sensor used by the [[Pontiac Fiero]] [[ECM]].

The throttle position sensor tells the ECM how far the throttle is opened. The ECM uses this information for fuel control, acceleration enrichment, idle behavior, deceleration behavior, and diagnostic trouble code decisions.

== Overview ==

The throttle position sensor, often abbreviated as TPS, is mounted on the throttle body and is connected to the throttle shaft.

As the throttle opens and closes, the TPS signal changes. The ECM uses this signal to determine driver demand and engine operating conditions.

A faulty, misadjusted, disconnected, or poorly connected TPS can cause drivability problems and may set diagnostic trouble codes.

== Location ==

{{Image wanted|Photo or diagram showing the throttle position sensor location on the Fiero throttle body. Ideally include both the 2.8L V6 and 2.5L four-cylinder locations if different.}}

The throttle position sensor is mounted on the throttle body.

On the 2.8L V6, the TPS is mounted on the side of the throttle body and is operated by the throttle shaft.

On the 2.5L four-cylinder, the TPS is also mounted on the throttle body, though the exact appearance and access may vary by year and engine configuration.

The TPS should not be confused with the [[Idle air control valve]], which is also associated with the throttle body but performs a different function.

== Sensor operation ==

The TPS sends a variable voltage signal to the ECM.

In general:

* Closed throttle produces a low voltage signal.
* Opening the throttle increases the voltage signal.
* Wide-open throttle produces a high voltage signal.

The signal should change smoothly as the throttle is opened and closed.

== Related trouble codes ==

Throttle-position-sensor-related diagnostic trouble codes include:

* [[Code 21]] - Throttle position sensor circuit, high voltage
* [[Code 22]] - Throttle position sensor circuit, low voltage

== Code 21 ==

[[Code 21]] indicates that the ECM is seeing a TPS signal voltage that is higher than expected.

Possible causes include:

* Misadjusted throttle position sensor
* Faulty throttle position sensor
* TPS connector problem
* TPS wiring problem
* Short to voltage in the TPS signal circuit
* Throttle linkage or throttle plate not returning correctly
* ECM input problem

== Code 22 ==

[[Code 22]] indicates that the ECM is seeing a TPS signal voltage that is lower than expected.

Possible causes include:

* Disconnected throttle position sensor
* Misadjusted throttle position sensor
* Faulty throttle position sensor
* TPS connector problem
* TPS wiring problem
* Open circuit in the TPS signal wire
* Short to ground in the TPS signal circuit
* ECM input problem

== Symptoms ==

Possible symptoms of a TPS or TPS circuit problem include:

* Check engine light
* Hesitation
* Poor throttle response
* Poor acceleration
* High idle
* Rough idle
* Stalling
* Surging
* Poor fuel economy
* Unusual drivability behavior

== Diagnosis ==

Basic diagnostic checks include:

# Check for stored diagnostic trouble codes.
# Inspect the TPS connector.
# Check whether the TPS is disconnected.
# Inspect TPS wiring for damage.
# Check that the throttle linkage moves freely.
# Check that the throttle plate returns fully.
# Check TPS adjustment if applicable.
# Check TPS voltage with the throttle closed and while opening the throttle.
# Watch for sudden jumps, dropouts, or dead spots in the signal.
# Check ECM connector condition if the sensor and wiring appear correct.

== Throttle body relationship ==

The TPS is mounted on the throttle body and follows throttle movement. Problems with the throttle body or linkage can therefore affect TPS readings.

Related topics:

* [[Throttle body]]
* [[Idle air control valve]]
* [[Idle problems]]
* [[Vacuum leaks]]

== ALDL data ==

Live ECM data through [[ALDL diagnostics]] can be useful when diagnosing TPS problems.

If ALDL data shows an incorrect throttle position at idle, or if the value does not change smoothly as the throttle is opened, the TPS, connector, wiring, or adjustment should be checked.

== Notes ==

A TPS trouble code does not automatically mean the TPS itself has failed.

Wiring faults, poor connectors, misadjustment, throttle linkage problems, and ECM input problems can all cause TPS-related trouble codes.

Do not adjust unrelated throttle-body settings unless the service procedure calls for it. Incorrect throttle-body adjustment can create additional idle and drivability problems.

== See also ==

* [[Diagnostic trouble codes]]
* [[ALDL diagnostics]]
* [[ECM]]
* [[Throttle body]]
* [[Idle air control valve]]
* [[Idle problems]]
* [[Code 21]]
* [[Code 22]]
* [[Code 35]]

[[Category:Fieropedia]]
[[Category:Diagnostics]]
[[Category:Electrical system]]
[[Category:Engine]]

Throttle position sensor - Revision history