Dodge R1500 1999 Service Manual page 389

made.
* When using a jumper wire, ensure either jumper wire or
circuit is fuse-protected.
* Before disconnecting connector from any control module,
ensure ignition is off before removing connector.
* When checking voltage or continuity at any control module,
probe connector for control module from pin side. DO NOT
backprobe connector or probe wires through insulation.
* DO NOT cause short circuits when performing electrical tests.
This will set additional Diagnostic Trouble Codes (DTCs),
making diagnosis of original problem more difficult.
* Use specified test equipment when performing electrical
tests.
RETRIEVING DIAGNOSTIC TROUBLE CODES
NOTE: Self-diagnostic tests are written specifically for Chrysler's
Diagnostic Readout Box (DRB). If using a generic scan tool,
ensure it is OBD-II certified. A generic scan tool may not be
capable of performing all necessary test functions.
Ensure battery is fully charged. Turn ignition off. Connect
scan tool to Data Link Connector (DLC). DLC is located under left side
of instrument panel. Turn ignition on. Using scan tool manufacturer's
instructions, record all DTCs displayed on scan tool. If ant DTCs are
retrieved, perform appropriate test under DIAGNOSTIC TESTS. Once all
repairs are made, clear DTCs. See CLEARING DIAGNOSTIC TROUBLE CODES.
If no DTCs are retrieved and fault still exists, go to CHECKING SPEED
CONTROL OPERATION under SYSTEM TESTS.
CLEARING DIAGNOSTIC TROUBLE CODES
Ensure ignition is off. Connect scan tool to DLC. Turn
ignition on. Using screen prompts on scan tool, erase DTCs from PCM.
DIAGNOSTIC TESTS
FTC P0720: LOW OUTPUT SPEED SENSOR (OSS) RPM MORE THAN 15 MPH
FTC P0720 will set if output shaft speed is less than 60 RPM
for 2.6 seconds when vehicle speed is more than 15 MPH.
Possible Causes:
* Defective Output Speed Sensor (OSS).
* OSS signal circuit open or shorted.
* OSS ground circuit open or shorted.
* Park/Neutral Position (PNP) switch FTC present.
* Defective PNP switch.
* Defective PCM.
1) Turn ignition on. Using scan tool, read DTCs. If FTC
specific good trip is displayed and equal to zero, go to next step. If
FTC specific good trip is equal to more than zero, go to step 13).
2) If there are any Park/Neutral Position (PNP) switch DTCs,
repair PNP switch FTC first. Perform TEST VER-5A under VERIFICATION
TESTS. If there are no PNP switch DTCs, go to next step.
3) Using scan tool, read PNP switch state. While observing
scan tool, shift transmission through all positions. If scan tool did
not display P/N and D/R in correct positions, repair PNP switch or
circuit as necessary. Perform TEST VER-5A under VERIFICATION TESTS. If