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Electrical Power Steering System (Eps): Specifications Honda S2000 AP1

Electronic Steering 11 illustrations ~1559 words

Torque Sensor Neutral Position

The EPS control unit stores the torque sensor neutral position in the EEPROM. The torque sensor neutral position must be memorized whenever the gearbox, the torque sensor, or the EPS control unit is replaced.

Note. The torque sensor neutral position is not effected when erasing the DTCs.

Torque Sensor

When the steering wheel is turned, twist occurs in the torsion bar between the steering side of the input shaft and the output shaft on the road reaction force side. Inductance is changed by the movement of the core. The amount this voltage changes (varies with the amount of movement, and direction of the core) is amplified with the interface circuitry of the sensor coil, and output to the EPS control unit as a steer signal.

Scheme 1

Scheme 1: Torque Sensor
Scheme 1: Torque Sensor

DTC 12: Torque Sensor PVF

  1. Turn the ignition switch to ON (II).
  2. Clear the DTC with the HDS.
  3. Turn the ignition switch to LOCK (0).
  4. Start the engine.
  5. Wait at least 10 seconds. Does the EPS indicator come on? YES -Go to step 6. NO -Check for loose terminals or poor connections. If the connections are good, the system is OK at this time.
  6. Check for DTCs with the HDS. Is DTC 12 indicated? YES -Check for loose terminals in the EPS control unit connectors. If necessary, substitute a known-good EPS control unit and recheck. NO -Troubleshoot the indicated DTC.

Scheme 2

Scheme 2: DTC 14: Torque Sensor (Resistance)
Scheme 2: DTC 14: Torque Sensor (Resistance)

Scheme 3

Scheme 3
Scheme 3

Scheme 4

Scheme 4
Scheme 4

Scheme 5

Scheme 5
Scheme 5

Scheme 6

Scheme 6
Scheme 6
  1. Turn the ignition switch to ON (II).
  2. Clear the DTC with the HDS.
  3. Turn the ignition switch to LOCK (0).
  4. Start the engine.
  5. Turn the steering wheel fully to the left, and hold it in that position for 10 seconds or more. Does the EPS indicator come on? YES -Go to step 6. NO -Check for loose terminals or poor connections. If the connections are good, the system is OK at this time.
  6. Check for DTCs with the HDS. Is DTC 14 indicated? YES -Go to step 7. NO -Troubleshoot the indicated DTC.
  7. Turn the ignition switch to LOCK (0).
  8. Disconnect the torque sensor 3P connector and EPS control unit connector B (14P).
  9. Check for continuity between torque sensor 3P connector terminals No. 1 and No. 2. Is there continuity? YES -Repair short between the BLU/RED and PNK wires in the torque sensor circuit between the torque sensor and the EPS control unit. NO -Go to step 1 1 .
  10. Check for continuity between torque sensor 3P connector terminals No. 2 and No. 3. Is there continuity? YES -Repair short between the WHT/GRN and BLU/RED wires in the torque sensor circuit between the torque sensor and the EPS control unit. NO -Go to step 1 1 .
  11. Check for continuity between torque sensor 3P connector terminals No. 1 and No. 3. Is there continuity? YES -Repair short between the WHT/GRN and PNK wires in the torque sensor circuit between the torque sensor and the EPS control unit. NO -Go to step 1 1 .
  12. On the sensor side, measure the resistance between the torque sensor 3P connector terminals No. 1 and No. 2, and between terminals No. 2 and No. 3. Is the resistance between 12- 14 ohms (at 68°F, 20°C)? YES -Go to step 1 1 . NO -Replace the torque sensor.
  13. Check for continuity between the appropriate EPS control unit connector B (14P) and torque sensor 3P connector terminals (see table). TERMINAL CONTINUITY REFERENCE Terminal name Torque sensor terminal No. EPS control unit terminal No. VS1 1 3 PVF 2 7 VS2 3 11 Is there continuity? YES -The EPS system is OK at this time. Check for loose terminals in the EPS control unit connectors. If necessary, substitute a known-good EPS control unit and recheck. NO -Repair open in the appropriate torque sensor circuit between the EPS control unit and the torque sensor.

Scheme 7

Scheme 7: DTC 21: Voltage for IG1
Scheme 7: DTC 21: Voltage for IG1

Scheme 8

Scheme 8
Scheme 8
  1. Turn the ignition switch to ON (II).
  2. Check the BATTERY in the DATA LIST with the HDS. Is the voltage at 9.2- 17.4 V? YES -Check for loose terminals or poor connections. If the connections are good, the system is OK at this time. NO -Go to step 3.
  3. Turn the ignition switch to LOCK (0).
  4. Check the No. 5 (7.5 A) fuse in the under-dash fuse/ relay box, and reinstall the fuse if it is OK. NOTE: All indicators except the charging system indicator will not come on when the No. 5 (7.5 A) fuse in the under-dash fuse/relay box is blown. Is the fuse blown? YES -Go to step 5. NO -Reinstall the checked fuse, then go to step 13 .
  5. Disconnect EPS control unit connector B (14P).
  6. Check for continuity between EPS control unit connector B (14P) terminal No. 1 and body ground. Is there continuity? YES -Repair short to body ground in the wire between the EPS control unit and the No. 5 (7.5 A) fuse in the under-dash fuse/relay box. NO -Install a new No. 5 (7.5 A) fuse in the under-dash fuse/relay box, then go to step 7.
  7. Reconnect the EPS control unit connector B (14P).
  8. Turn the ignition switch to ON (II).
  9. Clear the DTC with the HDS.
  10. Turn the ignition switch to LOCK (0).
  11. Start the engine.
  12. Check for DTCs with the HDS. Is DTC 21 indicated? YES -Replace the EPS control unit (see «GEARBOX BRACKET REMOVAL/INSTALLATION»(ref-351951-S34853274442009122900000) ). NO -Troubleshooting is complete. If any other DTCs are indicated, go to the indicated DTCs troubleshooting.
  13. Disconnect EPS control unit connector B (14P).
  14. Turn the ignition switch to ON (II).
  15. Measure the voltage between EPS control unit connector B (14P) terminal No. 1 and body ground. Is there battery voltage? YES -Check for loose terminals in the EPS control unit connectors, and repair if necessary. If no poor connections are found, replace the EPS control unit (see «GEARBOX BRACKET REMOVAL/INSTALLATION»(ref-351951-S34853274442009122900000) ). NO -Repair open in the wire between the EPS control unit and the No. 5 (7.5 A) fuse in the under-dash fuse/relay box.

Memorizing the Torque Sensor Neutral Position

The torque sensor neutral position must be memorized whenever the gearbox is removed or installed, or when the torque sensor or EPS control unit is replaced, and after doing wheel alignment. Note that the torque sensor neutral position is not affected when erasing the DTC.

Scheme 9

Scheme 9: Memorizing the Torque Sensor Neutral Position
Scheme 9: Memorizing the Torque Sensor Neutral Position

Scheme 10

Scheme 10
Scheme 10
  1. With the ignition switch in LOCK (0), connect the HDS to the data link connector (DLC) (A) located under the driver's side of the dashboard.
  2. With the vehicle on the ground, set the front wheels in the straight ahead driving position.
  3. Turn the ignition switch to ON (II).
  4. '06-09 models; make sure the HDS communicates with the vehicle and the EPS control unit. If it doesn't, troubleshoot the DLC circuit (see «DLC CIRCUIT TROUBLESHOOTING»(ref-351945-S34342936082009122900000) ).
  5. Turn the ignition switch to LOCK (0).
  6. Short the SCS circuit using the HDS.
  7. Turn the steering wheel 45 degrees to the left from the straight ahead driving position, and hold the steering wheel in that position.
  8. Turn the ignition switch to ON (II). The EPS indicator comes on, then it goes off after 4 seconds.
  9. Within 4 seconds after the EPS indicator goes off, return the steering wheel to the straight ahead driving position and release the steering wheel. The EPS indicator comes on again 4 seconds after releasing the steering wheel.
  10. Within 4 seconds after the EPS indicator comes on, turn the steering wheel 45 degrees to the left again and hold it in that position.
  11. The EPS indicator goes off after 4 seconds.
  12. Within 4 seconds after the EPS indicator goes off, return the steering wheel to the straight ahead driving position and release the steering wheel. Do not move the steering wheel before turning the ignition switch to LOCK (0). NOTE: If the steering wheel is moved, the torque sensor neutral position cannot be written to memory.
  13. The EPS indicator blinks twice 4 seconds after releasing the steering wheel, then it blinks three times 5 seconds after. Then, the indicator goes off. The torque sensor neutral position is memorized. NOTE: If the EPS indicator stays on, there was an error in writing the torque sensor neutral position to memory. Repeat the procedure starting from step 3.
  14. Turn the ignition switch to LOCK (0).
  15. Disconnect the HDS from the DLC.

Torque Sensor Replacement

Note these items during replacement

  1. Do not allow dust, dirt, or other foreign materials to enter the gearbox.
  2. Do not try to disassemble the torque sensor assembly. If the torque sensor is faulty, replace it as an assembly.
  3. If the torque sensor is replaced, the EPS control unit must memorize the torque sensor neutral position (see «MEMORIZING THE TORQUE SENSOR NEUTRAL POSITION»(ref-351951-S39897370852009122900000) ).

Scheme 11

Scheme 11
Scheme 11
  1. Center the steering rack within its stroke.
  2. Remove the torque sensor assembly (A).
  3. Coat the new O-ring (B) with multipurpose grease, and carefully fit it on the torque sensor housing.
  4. Apply multipurpose grease to the needle bearing (C) in the gearbox housing.
  5. Install the torque sensor assembly on the gearbox housing by engaging the gear. The alphabet stamping (for example "AB") (D) on the pinion shaft aligns with the rack guide screw (E) when the rack is in the straight ahead driving position. When installing the torque sensor assembly, make sure the "alphabet" stamping ("AB") is within the range shown.
  6. Tighten the 8 mm flange bolts (F) to the specified torque.

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