Dodge Ram Truck 1500-2500-3500. Manual — part 1157

P0121-TP SENSOR VOLTAGE DOES NOT AGREE WITH MAP (CONTINUED)

2.

MAP SENSOR OPERATION

Start the engine.

With the scan tool, monitor the MAP Sensor voltage.

Snap the throttle.

Does the scan tool display MAP voltage from below 2.0 volts at idle to above 3.5 volts at WOT?

Yes

>> Go To 3

No

>> Go To 10

3.

TP SENSOR OPERATION

Ignition on, engine not running.

With the scan tool, monitor the TP Sensor voltage while slowly depressing the throttle pedal from the idle position
to the wide open throttle position.

Does voltage start at approximately 0.8 of a volt and go above 3.5 volts with a smooth transition?

Yes

>> Refer to the INTERMITTENT CONDITION Diagnostic Procedure. (Refer to 9 - ENGINE - DIAGNOSIS

AND TESTING)

Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

No

>> Go To 4

4.

RESISTANCE IN THE (F855) 5-VOLT SUPPLY CIRCUIT

Turn the ignition off.

Disconnect the TP Sensor harness connector.

Disconnect the PCM harness connectors.

Measure the resistance of the (F855) 5-volt Supply circuit from the TP
Sensor harness connector to the PCM harness connector.

Is the resistance below 5.0 ohms?

Yes

>> Go To 5

No

>> Repair the excessive resistance in the (F855) 5-volt Sup-

ply circuit.

Perform the POWERTRAIN VERIFICATION TEST. (Refer
to 9 - ENGINE - STANDARD PROCEDURE)

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ENGINE - ELECTRICAL DIAGNOSTICS - SRT-10

DR/DH

P0121-TP SENSOR VOLTAGE DOES NOT AGREE WITH MAP (CONTINUED)

5.

TP SENSOR (F855) 5-VOLT SUPPLY CIRCUIT SHORTED TO GROUND

Measure the resistance between ground and the (F855) 5-volt Supply
circuit at the TP Sensor harness connector.

Is the resistance below 100 ohms?

Yes

>> Repair the short to ground in the (F855) 5-volt Supply cir-

cuit.

Perform the POWERTRAIN VERIFICATION TEST. (Refer
to 9 - ENGINE - STANDARD PROCEDURE)

No

>> Go To 6

6.

THROTTLE POSITION SENSOR

Connect the PCM harness connectors.

With the scan tool, monitor the TP Sensor voltage.

Ignition on, engine not running.

Connect a jumper wire between the (K22) TP Sensor No.1 Signal cir-
cuit and the (K900) Sensor ground circuit.

Did the TP Sensor voltage change from approximately 4.9 volts
to below 0.5 of a volt with the jumper

Yes

>> Replace the Throttle Position Sensor.

Perform the POWERTRAIN VERIFICATION TEST. (Refer
to 9 - ENGINE - STANDARD PROCEDURE)

No

>> Go To 7

NOTE: Remove the jumper wire before continuing.

DR/DH

ENGINE - ELECTRICAL DIAGNOSTICS - SRT-10

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P0121-TP SENSOR VOLTAGE DOES NOT AGREE WITH MAP (CONTINUED)

7.

RESISTANCE IN THE (K22) TP SENSOR SIGNAL CIRCUIT

Turn the ignition off.

Disconnect the PCM harness connectors.

Measure the resistance of the (K22) TP Sensor No.1 Signal circuit
from the TP Sensor harness connector to the PCM harness connector.

Is the resistance below 5.0 ohms?

Yes

>> Go To 8

No

>> Repair the excessive resistance in the (K22) TP Sensor

No.1 Signal circuit.

Perform the POWERTRAIN VERIFICATION TEST. (Refer
to 9 - ENGINE - STANDARD PROCEDURE)

8.

(K22) TP SENSOR NO.1 SIGNAL CIRCUIT SHORTED TO GROUND

Measure the resistance between ground and the (K22) TP Sensor
No.1 Signal circuit at the TP Sensor harness connector.

Is the resistance below 5.0 ohms?

Yes

>> Repair the short to ground in the (K22) TP Sensor No.1

Signal circuit.

Perform the POWERTRAIN VERIFICATION TEST. (Refer
to 9 - ENGINE - STANDARD PROCEDURE)

No

>> Go To 9

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ENGINE - ELECTRICAL DIAGNOSTICS - SRT-10

DR/DH

P0121-TP SENSOR VOLTAGE DOES NOT AGREE WITH MAP (CONTINUED)

9.

RESISTANCE IN (K900) SENSOR GROUND CIRCUIT

Measure the resistance of the (K900) Sensor ground circuit from the
TP Sensor harness connector to the PCM harness connector.

Is the resistance below 5.0 ohms?

Yes

>> Go To 16

No

>> Repair the excessive resistance in the (K900) Sensor

ground circuit.

Perform the POWERTRAIN VERIFICATION TEST. (Refer
to 9 - ENGINE - STANDARD PROCEDURE)

10.

EXCESSIVE RESISTANCE IN THE (F855) 5-VOLT SUPPLY CIRCUIT

Turn the ignition off.

Disconnect the MAP Sensor harness connector.

Disconnect the PCM harness connectors.

Measure the resistance of the (F855) 5-volt Supply circuit from the
MAP Sensor harness connector to the PCM harness connector.

Is the resistance below 5.0 ohms?

Yes

>> Go To 11

No

>> Repair the excessive resistance in the (F855) 5-volt Sup-

ply circuit.

Perform the POWERTRAIN VERIFICATION TEST. (Refer
to 9 - ENGINE - STANDARD PROCEDURE)

DR/DH

ENGINE - ELECTRICAL DIAGNOSTICS - SRT-10

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