Dodge Ram Truck 1500-2500-3500. Manual — part 807

P0128-THERMOSTAT RATIONALITY (CONTINUED)

11.

SIGNAL CIRCUIT SHORTED TO GROUND

Measure the resistance between ground and the Sensor Signal circuit
in the Temperature Sensor harness connector.

Is the resistance below 100 ohms?

Yes

>> Repair the short to ground in the Signal circuit.

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

No

>> Go To 12

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ENGINE - ELECTRICAL DIAGNOSTICS - 3.7L/4.7L/5.7L

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P0128-THERMOSTAT RATIONALITY (CONTINUED)

12.

SIGNAL CIRCUIT SHORTED TO THE (K900) SENSOR GROUND CIRCUIT

Measure the resistance between the Signal circuit and the (K900)
Sensor ground circuit in the (K2) ECT Sensor harness connector.

Measure the resistance between the Signal circuit and the (K900)
Sensor ground circuit in the (G31) AAT Sensor harness connector.

Is the resistance below 100 ohms?

Yes

>> Repair the short between the (K900) Sensor ground circuit

and the appropriate Sensor Signal circuit.

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

No

>> Go To 13

13.

PCM

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.

Were there any problems found?

Yes

>> Repair as necessary.

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

No

>> Replace and program the Powertrain Control Module per Service Information.

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

DR/DH

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P0129-BAROMETRIC PRESSURE OUT-OF-RANGE LOW

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P0129-BAROMETRIC PRESSURE OUT-OF-RANGE LOW (CONTINUED)

For the Engine circuit diagram (Refer to 9 - ENGINE - SCHEMATICS AND DIAGRAMS).

For a complete wiring diagram Refer to Section 8W.

•

When Monitored:
With the ignition key on. No Cam or Crank signal within 75 ms. Engine speed less than 250 RPM.

•

Set Condition:
The PCM senses the voltage from the MAP sensor to be less than 2.2 volts but above 0.04 of a volt for 300
milliseconds. One Trip Fault. Three good trips to turn off the MIL. (5.7L ETC lamp will flash)

Possible Causes

(F856) 5-VOLT SUPPLY CIRCUIT SHORTED TO BATTERY VOLTAGE

(F856) 5-VOLT SUPPLY CIRCUIT OPEN

(F856) 5-VOLT SUPPLY CIRCUIT SHORTED TO GROUND

(K1) MAP SIGNAL CIRCUIT OPEN

(K1) MAP SIGNAL CIRCUIT SHORTED TO GROUND

(K1) MAP SIGNAL CIRCUIT SHORTED TO THE (K900) SENSOR GROUND CIRCUIT

MAP SENSOR

PCM

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE -
DIAGNOSIS AND TESTING).

Diagnostic Test

1.

ACTIVE DTC

Ignition on, engine not running.

With a scan tool, read DTCs.

Is the DTC active at this time.

Yes

>> Go To 2

No

>> Refer to the INTERMITTENT CONDITION Diagnostic Procedure.

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

DR/DH

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