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Code 1-2: Pump Motor Circuit

  1. Check ABS fuses and replace if necessary. Remove pump motor relay. Test relay and replace if necessary. See RELAY TEST  under DIAGNOSIS & TESTING. If relay is stuck in ON position, pump motor may be damaged. If relay is okay, bleed high pressure fluid from modulator bleed screw. See RELIEVING SYSTEM PRESSURE  under BLEEDING BRAKE SYSTEM.
  2. Remove pump motor relay. Connect jumper wire between "B+" terminal and motor terminal of pump motor relay holder. See Fig 1 . If pump motor runs, go to next step. If pump motor does not run, go to step 8).
  3. Remove jumper wire. Disconnect 3-pin connector from underhood ABS fuse/relay box. Turn ignition on. Measure voltage between motor terminal of pump motor relay holder and ground. If battery voltage does not exist, go to step 11). If battery voltage exists, go to next step.
  4. Measure voltage between Black/Yellow wire of 3-pin connector and ground. If battery voltage is present, go to next step. If battery voltage does not exist, repair open Black/Yellow wire between underdash fuse/relay box and underhood ABS fuse/relay box.
  5. Reconnect 3-pin connector to underhood ABS fuse/relay box. Install pump motor relay. If pump motor operates, go to step 14). If pump motor does not operate, backprobing connector, measure voltage between Yellow/Red wire terminal of underhood ABS fuse/relay box 3-pin connector and ground. If battery voltage exists, go to next step. If battery voltage does not exist, replace underhood ABS fuse/relay box.
  6. Backprobing connector, measure voltage between Yellow/Red wire terminal of ABS control unit 22-pin connector and ground. If battery voltage does not exist, repair open Yellow/Red wire between underhood ABS fuse/relay box and ABS control unit. If battery voltage exists, go to next step.
  7. Reconnect connectors. Bleed high pressure fluid. See RELIEVING SYSTEM PRESSURE  under BLEEDING BRAKE SYSTEM. Add clean brake fluid if necessary. Start engine and check for DTC 1-2. If DTC 1-2 is still present, replace ABS control unit.
  8. Measure voltage between battery terminal of underhood ABS fuse/relay box and ground. If battery voltage does not exist, repair open White wire between battery and underhood ABS fuse/relay box. If battery voltage is present, measure voltage between underhood ABS fuse/relay box 3-pin connector White wire terminal and ground. If battery voltage is not present, replace underhood ABS fuse/relay box. If battery voltage is present, go to next step.
  9. Disconnect ABS pump motor 2-pin connector. Measure voltage between White wire terminal of pump motor connector and ground. If battery voltage exists, go to next step. If battery voltage does not exist, repair open White wire between underhood ABS fuse/relay box and pump motor.
  10. Measure voltage between pump motor connector terminals. If battery voltage exists, replace pump motor. If battery voltage does not exist, check pump motor ground connection. If ground connection is okay, repair open Black wire between pump motor and ground.
  11. Disconnect 4-pin connector from underhood ABS fuse/relay box. Measure voltage between Brown/Yellow wire terminal of 4-pin connector and ground. If battery voltage does not exist, go to next step. If battery voltage exists, replace underhood ABS fuse/relay box.
  12. Backprobing connector, measure voltage between Brown/Yellow wire terminal of ABS control unit 26-pin connector and ground. If battery voltage exists, repair open Brown/Yellow wire between underhood ABS fuse/relay box and ABS control unit. If battery voltage does not exist, go to next step.
  13. Check for loose ABS control unit connectors. If connectors are okay, install known-good ABS control unit and retest.
  14. Remove pump motor relay. Disconnect 3-pin connector from underhood ABS fuse/relay box. Check continuity between PMR terminal of pump motor relay holder and ground. See Fig 1 . If continuity does not exist, go to next step. If continuity exists, replace underhood ABS fuse/relay box.
  15. Disconnect ABS control unit 22-pin connector. Check continuity between Yellow/Red wire terminal of 22-pin connector and ground. If continuity exists, Yellow/Red wire between underhood ABS fuse/relay box and ABS control unit is shorted to ground. If continuity does not exist, check for loose ABS control unit connectors. If connectors are okay, install and known-good ABS control unit and recheck.
Fig 1: Identifying ABS Pump Motor Relay Holder Terminals
G94H47420Courtesy of AMERICAN HONDA MOTOR CO., INC.
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