Test M: Open Or Shorted Isolation (ISO) Valve
NOTE:
DTCs C1198/C1200, C1214/C1216, C1250/C1252 or C1254/C1256 are generated when ABCM detects an incorrect voltage feedback signal from Isolation (ISO) Valve Solenoid (when it is expected to be battery voltage). Possible conditions include a defective ISO or ABCM, or open or short in related wiring.
- Turn ignition off. Connect NGS tester or scan tool. Turn ignition on. Clear continuous DTCs. See CLEARING DIAGNOSTIC TROUBLE CODES . Perform DRIVE CYCLE TEST . Retrieve and document continuous DTCs. Turn ignition off. If DTC C1198, C1241, C1250 or C1254 are retrieved, go to next step. If DTC C1200, C1216, C1252 or C1256 is retrieved, go to step 6 . If different DTCs are retrieved, see DIAGNOSTIC TROUBLE CODE DEFINITIONS table. If no DTCs are retrieved and SYSTEM PASS is obtained, go to step 8 .
- Turn ignition off. Connect Breakout Box to ABS control module (ABCM) harness. Measure resistance between positive lead on Breakout Box pin No. 30 and negative lead at each of pins No. 47, 49, 8 and 9. If resistance is 3-6 ohms, go to step 5 . If resistance is not 3-6 ohms, go to next step.
- Disconnect HCU connector. Measure resistance between HCU terminals: for DTC C1198 (LF ISO valve), terminals No. 8 and 3; for DTC C1214 (RF ISO valve), terminals No. 2 and 4; for DTC C1250 (left rear ISO valve), terminals No. 1 and 5; and for DTC C1254 (right rear ISO valve), terminals No. 7 and 12. See Figure . If resistance were all 3-6 ohms, go to next step. If any resistance was not 3-6 ohms, replace HCU coil unit, then go to step 8 .
- Measure resistance between Breakout Box pins: for DTC C1198, terminals No. 47 and 8 (Brown wire) for DTC C1214, terminals No. 49 and 2 (Pink wire) for DTC C1250, terminals No. 8 and 1 (Light Green/Black wire) and for DTC C1254, terminals No. 9 and 7 (Pink/White wire). If resistance is less than 5 ohms, replace ABCM and go to step 8 . If resistance is more than 5 ohms, repair appropriate wire between HCU and ABCM, and go to step 8 . See Fig 1 .
- Disconnect HCU connector. Measure resistance between Breakout Box pin No. 60 (ground) and pin No. 47 (DTC C1198), 49 (DTC C1214), 8 (DTC C1250) or 9 (DTC C1254). If resistance is more than 10 k/ohms, replace ABCM and go to step 8 . If resistance is less than 10 k/ohms, repair appropriate wire circuit, then go to step 8 .
- Turn ignition off. Connect Breakout Box. Measure resistance between pins of Breakout Box, with pin No. 30, (Yellow wire). Depending on DTC, touch negative lead to pin No. 47 (DTC C1200), No. 49 (DTC C1216), No. 8 (DTC C1252) or No. 9 (DTC C1256). If resistance is 3-6 ohms, go to next step. If resistance is not 3-6 ohms, repair HCU coil assembly, then go to step 8 .
- Turn ignition on. Measure voltage between Breakout Box pin No. 60 and pins No. 47 (DTC C1200), No. 49 (DTC C1216), No. 8 (DTC C1252) or No. 9 (DTC C1256). If voltage is present, repair appropriate wire circuit(s), then go to next step. If voltage is not present, replace ABCM, then go to next step.
- Restore ABS system and connect all components. Clear continuous DTCs. Perform DRIVE CYCLE TEST . Retrieve and document continuous DTCs. If SYSTEM PASS is obtained, repair is complete. If SYSTEM PASS is not obtained and original DTC is retrieved, go back to step 1 . If a different DTC is retrieved, see DIAGNOSTIC TROUBLE CODE DEFINITIONS table.