DTC P0791, P0794 [5R55S]

id0502c1814100

DTC P0791

Intermediate shaft speed (ISS) sensor malfunction

DTC P0794

Intermediate shaft speed (ISS) sensor signal noise
DETECTION CONDITION
•  P0791: TCM detects insufficient ISS sensor signal while driving
•  P0794: TCM detects intermittent ISS sensor signal input while driving
POSSIBLE CAUSE
•  ISS sensor malfunction.
•  Short to ground in wiring harness between ISS sensor terminal A (wiring harness-side) and TCM terminal AS (wiring harness-side).
•  Open circuit in wiring harness between ISS sensor terminal A (wiring harness-side) and TCM terminal AS (wiring harness-side).
•  Open circuit in wiring harness between ISS sensor terminal B (wiring harness-side) and TCM terminal AM (wiring harness-side).
•  Damaged connectors between ISS sensor and TCM.
•  TCM malfunction.

Diagnostic procedure

STEP

INSPECTION

ACTION
1
VERIFY FREEZE FRAME DATA HAS BEEN RECORDED
•  Has the FREEZE FRAME DATA been recorded?
Yes
Go to the next step.
No
Record the FREEZE FRAME DATA on the repair order, then go to the next step.
2
VERIFY RELATED SERVICE INFORMATION AVAILABILITY
•  Verify related Service Information availability.
•  Is any related Service Information available?
Yes
Perform repair or diagnosis according to the available Service Information.
•  If the vehicle is not repaired, go to the next step.
No
Go to the next step.
3
INSPECT ISS SENSOR CONNECTOR FOR POOR CONNECTION
•  Turn the engine switch to the LOCK position.
•  Disconnect the ISS sensor connector.
•  Inspect for poor connection (such as damaged/pulled-out pins, corrosion)
•  Is the connection normal?
Yes
Go to the next step.
No
Repair or replace connector and/or terminal, then go to Step 8.
4
INSPECT ISS SENSOR CIRCUIT FOR SHORT TO GROUND
•  Inspect for continuity between ISS sensor connector A (wiring harness-side) and body ground.
•  Is there continuity?
Yes
Repair or replace the wiring harness, then go to Step 8.
No
Go to the next step.
5
INSPECT TCM CONNECTOR FOR POOR CONNECTION
•  Disconnect the TCM connector.
•  Inspect for poor connection (such as damaged/pulled-out pins, corrosion).
•  Is the connection normal?
Yes
Go to the next step.
No
Repair or replace the connector and/or terminals, then go to Step 8.
6
INSPECT ISS SENSOR CIRCUIT FOR OPEN CIRCUIT
•  Inspect the following ISS sensor terminals (wiring harness-side) and TCM terminals (wiring harness-side):
―  A and AS
―  B and AM
•  Is there continuity?
Yes
Go to the next step.
No
Repair or replace the wiring harness, then go to Step 8.
7
INSPECT ISS SENSOR
•  Inspect the ISS sensor.
•  Is ISS sensor normal?
Yes
Go to the next step.
No
Replace the ISS sensor, then go to the next step.
(See INTERMEDIATE SHAFT SPEED (ISS) SENSOR REMOVAL/INSTALLATION [5R55S].)
8
VERIFY TROUBLESHOOTING OF DTC P0791 OR P0794 COMPLETED
•  Make sure to reconnect all the disconnected connectors.
•  Clear the DTC from memory using the IDS/PDS.
•  Perform the “After Repair Procedure”.
•  Are any DTCs present?
Yes
Replace the TCM, then go to the next step.
(See TCM REMOVAL/INSTALLATION [5R55S].)
No
Go to the next step.
9
VERIFY DTCS
•  Are DTCs except for P0791 and P0794 output?
Yes
Go to the applicable DTC inspection.
(See DTC TABLE [5R55S].)
No
DTC troubleshooting completed.