P0121-TP SENSOR VOLTAGE DOES NOT AGREE WITH MAP
When Monitored: With the engine running and no MAP sensor or TPS DTC’s set. Engine
speed must be greater than 1600 RPM.
Set Condition: The PCM performs two separate tests. When the manifold vacuum is low,
the TPS signal should be high. When the manifold vacuum is high, the TPS signal should
be low. If the proper TPS voltage is not detected when the two conditions are met, a DTC
will be set after 4 seconds.
POSSIBLE CAUSES
GOOD TRIP EQUAL TO ZERO
RESISTANCE IN (K7) MAP 5-VOLT SUPPLY CIRCUIT
(K7) MAP 5-VOLT SUPPLY SHORTED TO GROUND
MAP SENSOR
RESISTANCE IN THE (K1) MAP SENSOR SIGNAL CIRCUIT
(K1) MAP SENSOR SIGNAL CIRCUIT SHORTED TO GROUND
RESISTANCE IN (K4) MAP SENSOR GROUND CIRCUIT
TP SENSOR OPERATION
RESISTANCE IN (K7) TP SENSOR 5-VOLT SUPPLY CIRCUIT
(K7) TP SENSOR 5-VOLT SUPPLY CIRCUIT SHORTED TO GROUND
THROTTLE POSITION SENSOR
RESISTANCE IN THE (K22) TP SENSOR #1 SIGNAL CIRCUIT
(K22) TP SENSOR #1 SIGNAL CIRCUIT SHORTED TO GROUND
RESISTANCE IN (K4) SENSOR GROUND CIRCUIT
PCM
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DRIVEABILITY - GAS
TEST ACTION APPLICABILITY
1 NOTE: Diagnose any TP Sensor or MAP component DTCs first before
continuing.
NOTE: If the P0500 - No Vehicle Speed Signal is set along with this DTC,
refer to the P0500 diagnostics before continuing.
NOTE: The throttle plate and linkage should be free of binding and carbon
build up.
NOTE: Ensure the throttle plate is at the idle position.
Ignition on, engine not running.
NOTE: Repair any vacuum leaks that are present before continuing.
With the DRBIIIt, read DTCs and record the related Freeze Frame data.
Is the Good Trip displayed and equal to zero?
All
Yes ! Go To 2
No ! Refer to the INTERMITTENT CONDITION Symptom (Diagnostic
Procedure).
Perform POWERTRAIN VERIFICATION TEST VER - 5.
2 Start the engine.
With the DRBIIIt, monitor the MAP Sensor voltage.
Snap the throttle.
Does the DRBIIIt display MAP voltage from below 2.0 volts at idle to above 3.5 volts
at WOT?
All
Yes ! Go To 3
No ! Go To 10
3 Ignition on, engine not running.
With the DRBIIIt, monitor the TP Sensor voltage while slowly depressing the
throttle pedal from the idle position to the wide open throttle position.
Does voltage start approximately at 0.8 of a volt and go above 3.5 volts with a smooth
transition?
All
Yes ! Refer to the INTERMITTENT CONDITION Symptom (Diagnostic
Procedure).
Perform POWERTRAIN VERIFICATION TEST VER - 5.
No ! Go To 4
4 Turn the ignition off.
Disconnect the TP Sensor harness connector.
Disconnect the PCM harness connectors.
Measure the resistance of the (K7) 5-volt Supply circuit from the TP Sensor harness
connector to the PCM harness connector.
Is the resistance below 5.0 ohms?
All
Yes ! Go To 5
No ! Repair the excessive resistance in the (K7) TP Sensor 5-volt
Supply circuit.
Perform POWERTRAIN VERIFICATION TEST VER - 5.
5 Measure the resistance between ground and the (K7) 5-volt Supply circuit at the TPS
harness connector.
Is the resistance below 100 ohms?
All
Yes ! Repair the short to ground in the (K7) TP Sensor 5-volt Supply
circuit.
Perform POWERTRAIN VERIFICATION TEST VER - 5.
No ! Go To 6
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DRIVEABILITY - GAS
P0121-TP SENSOR VOLTAGE DOES NOT AGREE WITH MAP — Continued
TEST ACTION APPLICABILITY
6 Turn the ignition off.
Connect the PCM harness connectors.
With the DRBIIIt, monitor the TP Sensor voltage.
Ignition on, engine not running.
Connect a jumper wire between the (K22) TP Sensor #1 Signal circuit and the (K4)
Sensor ground circuit.
Does the DRBIIIt display TP Sensor voltage from approximately 4.9 volts to below
0.5 of a volt?
All
Yes ! Replace the Throttle Position Sensor.
Perform POWERTRAIN VERIFICATION TEST VER - 5.
No ! Go To 7
NOTE: Remove the jumper wire before continuing.
7 Turn the ignition off.
Disconnect the PCM harness connectors.
Measure the resistance of the (K22) TP Sensor #1 Signal circuit from the TP Sensor
harness connector to the PCM harness connector.
Is the resistance below 5.0 ohms?
All
Yes ! Go To 8
No ! Repair the excessive resistance in the (K22) TP Sensor #1 Signal
circuit.
Perform POWERTRAIN VERIFICATION TEST VER - 5.
8 Measure the resistance between ground and the (K22) TP Sensor #1 Signal circuit at
the TP Sensor harness connector.
Is the resistance below 5.0 ohms?
All
Yes ! Go To 9
No ! Repair the short to ground in the (K22) TP Sensor #1 Signal
circuit.
Perform POWERTRAIN VERIFICATION TEST VER - 5.
9 Measure the resistance of the (K4) Sensor ground circuit from the TP Sensor harness
connector to the PCM harness connector.
Is the resistance below 5.0 ohms?
All
Yes ! Go To 16
No ! Repair the excessive resistance in the (K4) Sensor ground circuit.
Perform POWERTRAIN VERIFICATION TEST VER - 5.
10 Turn the ignition off.
Disconnect the MAP Sensor harness connector.
Disconnect the PCM harness connectors.
Measure the resistance of the (K7) 5-volt Supply circuit from the MAP Sensor
harness connector to the PCM harness connector.
Is the resistance below 5.0 ohms?
All
Yes ! Go To 11
No ! Repair the excessive resistance in the (K7) 5-volt Supply circuit.
Perform POWERTRAIN VERIFICATION TEST VER - 5.
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DRIVEABILITY - GAS
P0121-TP SENSOR VOLTAGE DOES NOT AGREE WITH MAP — Continued
TEST ACTION APPLICABILITY
11 Measure the resistance between ground and the (K7) 5-volt Supply circuit at the
MAP Sensor harness connector.
Is the resistance above 100k ohms?
All
Yes ! Go To 12
No ! Repair the short to ground in the (K7) 5-volt Supply circuit.
Perform POWERTRAIN VERIFICATION TEST VER - 5.
12 Turn the ignition off.
Connect the PCM harness connectors.
Ignition on, engine not running.
With the DRBIIIt, monitor the MAP Sensor voltage.
Connect a jumper wire between the (K1) MAP Sensor Signal circuit and the (K4)
Sensor ground circuit .
Cycle the ignition switch from off to on.
Does the DRBIIIt display MAP voltage from approximately 4.9 volts to below 0.5 of
a volt?
All
Yes ! Replace the MAP Sensor.
Perform POWERTRAIN VERIFICATION TEST VER - 5.
No ! Go To 13
NOTE: Remove the jumper wire before continuing.
13 Turn the ignition off.
Disconnect the PCM harness connectors.
Measure the resistance of the (K1) MAP Sensor Signal circuit from the MAP Sensor
harness connector to the PCM harness connector.
Is the resistance below 5.0 ohms?
All
Yes ! Go To 14
No ! Repair the excessive resistance in the (K1) MAP Sensor Signal
circuit.
Perform POWERTRAIN VERIFICATION TEST VER - 5.
14 Measure the resistance between ground and the (K1) MAP Sensor Signal circuit at
the MAP Sensor harness connector.
Is the resistance below 100 ohms?
All
Yes ! Go To 15
No ! Repair the short to ground in the (K1) MAP Sensor Signal circuit.
Perform POWERTRAIN VERIFICATION TEST VER - 5.
15 Measure the resistance of the (K4) Sensor ground circuit from the MAP Sensor
harness connector to the PCM harness connector.
Is the resistance below 5.0 ohms?
All
Yes ! Go To 16
No ! Repair the excessive resistance in the (K4) Sensor ground circuit.
Perform POWERTRAIN VERIFICATION TEST VER - 5.
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DRIVEABILITY - GAS
P0121-TP SENSOR VOLTAGE DOES NOT AGREE WITH MAP — Continued
TEST ACTION APPLICABILITY
16 NOTE: Before continuing, check the PCM harness connector terminals for
corrosion, damage, or terminal push out. Repair as necessary.
Using the schematics as a guide, inspect the wire harness and connectors. Pay
particular attention to all Power and Ground circuits.
If there are no possible causes remaining, view repair.
All
Repair
Replace and program the Powertrain Control Module per Service
Information.
Perform POWERTRAIN VERIFICATION TEST VER - 5.
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DRIVEABILITY - GAS
P0121-TP SENSOR VOLTAGE DOES NOT AGREE WITH MAP —
