Dodge Ram Truck 1500-2500-3500. Manual — part 1103

P0580-LOW VOLTAGE DETECTED AT THE SPEED CONTROL SWITCH (CONTINUED)

For the Engine circuit diagram (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES/ENGINE CON-
TROL MODULE - SCHEMATIC - ELECTRICAL)

For a complete wiring diagram Refer to Section 8W.

•

When Monitored:
While the ignition is on

•

Set Condition:
Speed control MUX switch below 1.0 volts for 5 seconds.

Possible Causes

S/C WIRING HARNESS OBSERVABLE PROBLEM

S/C SWITCH (ON/OFF)

CLOCKSPRING SHORTED TO GROUND

S/C SWITCH (RESUME/ACCEL)

S/C SWITCH SIGNAL CIRCUIT SHORTED TO GROUND

S/C SIGNAL CIRCUIT SHORTED TO SENSOR GROUND

ECM

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

Diagnostic Test

1.

S/C SWITCH VOLTAGE BELOW 1.0 VOLT

Turn the ignition on.

With the scan tool, read the S/C Switch volts status in the ECM.

Is the S/C Switch voltage below 1.0 volt?

Yes

>> Go To 3

No

>> Go To 2

2.

S/C WIRING HARNESS OBSERVABLE PROBLEM

Turn the ignition off.

Using the Schematics as a guide, inspect the Wiring and Connectors.

Were any problems found?

Yes

>> Repair as necessary.

Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 8 - ELECTRICAL/ELEC-
TRONIC CONTROL MODULES/ENGINE CONTROL MODULE - DIAGNOSIS AND TESTING)

No

>> Go To 3

9 - 1334

ENGINE - ELECTRICAL DIAGNOSTICS - DIESEL

DR/DH

P0580-LOW VOLTAGE DETECTED AT THE SPEED CONTROL SWITCH (CONTINUED)

3.

S/C SWITCH (ON/OFF)

Turn the ignition off.

Disconnect the S/C ON/OFF Switch harness connector.

NOTE: Check connectors - Clean/repair as necessary.
Turn the ignition on.

With the scan tool in Sensors, read the S/C Switch volts in the ECM.

Did the S/C Switch volts change to 5.0 volts?

Yes

>> Replace the S/C ON/OFF Switch.

Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 8 - ELECTRICAL/ELEC-
TRONIC CONTROL MODULES/ENGINE CONTROL MODULE - DIAGNOSIS AND TESTING)

No

>> Go To 4

4.

S/C SWITCH (RESUME/ACCEL)

Turn the ignition off.

Disconnect the S/C RESUME/ACCEL Switch harness connector.

NOTE: Check connectors - Clean/repair as necessary.
Ignition on, engine not running.

With the scan tool in Sensors, read the S/C Switch volts in the ECM.

Did the S/C Switch volts go above 4.0 volts?

Yes

>> Replace the Resume/Accel Switch.

Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 8 - ELECTRICAL/ELEC-
TRONIC CONTROL MODULES/ENGINE CONTROL MODULE - DIAGNOSIS AND TESTING)

No

>> Go To 5

5.

CLOCKSPRING SHORTED TO GROUND

Turn the ignition off.

Disconnect the clockspring 6-way harness connector (instrument panel
wiring side).

Turn the ignition on.

With the scan tool in Sensors, read the S/C Switch volts in the ECM.

Did the S/C Switch volts change to 5.0 volts?

Yes

>> Replace the Clockspring.

Perform POWERTRAIN VERIFICATION TEST VER - 1
(DIESEL). (Refer to 8 - ELECTRICAL/ELECTRONIC CON-
TROL MODULES/ENGINE CONTROL MODULE - DIAG-
NOSIS AND TESTING)

No

>> Go To 6

DR/DH

ENGINE - ELECTRICAL DIAGNOSTICS - DIESEL

9 - 1335

P0580-LOW VOLTAGE DETECTED AT THE SPEED CONTROL SWITCH (CONTINUED)

6.

S/C SWITCH SIGNAL CIRCUIT SHORTED TO GROUND

Turn the ignition off.

Disconnect the S/C ON/OFF Switch harness connector.

Disconnect the ECM harness connectors.

NOTE: Check connectors - Clean/repair as necessary.
Measure the resistance between the S/C Switch Signal circuit and
ground (B-) at S/C ON/OFF Switch harness connector.

Is the resistance below 5.0 ohms?

Yes

>> Repair S/C Switch Signal Circuit for a short to ground.

Perform POWERTRAIN VERIFICATION TEST VER - 1
(DIESEL). (Refer to 8 - ELECTRICAL/ELECTRONIC CON-
TROL MODULES/ENGINE CONTROL MODULE - DIAG-
NOSIS AND TESTING)

No

>> Go To 7

7.

S/C SIGNAL CIRCUIT SHORTED TO SENSOR GROUND

Measure the resistance between the S/C Signal Circuit and the Sensor
Ground Circuit at the ON/OFF switch harness connector.

Is the resistance below 5.0 ohms?

Yes

>> Repair S/C Signal Circuit shorted to Sensor Ground.

Perform POWERTRAIN VERIFICATION TEST VER - 1
(DIESEL). (Refer to 8 - ELECTRICAL/ELECTRONIC CON-
TROL MODULES/ENGINE CONTROL MODULE - DIAG-
NOSIS AND TESTING)

No

>> Replace and program the ECM in accordance with the

Service Information.

Perform POWERTRAIN VERIFICATION TEST VER - 1
(DIESEL). (Refer to 8 - ELECTRICAL/ELECTRONIC CON-
TROL MODULES/ENGINE CONTROL MODULE - DIAG-
NOSIS AND TESTING)

9 - 1336

ENGINE - ELECTRICAL DIAGNOSTICS - DIESEL

DR/DH

P0581-HIGH VOLTAGE DETECTED AT THE SPEED CONTROL SWITCH

DR/DH

ENGINE - ELECTRICAL DIAGNOSTICS - DIESEL

9 - 1337