B7 (183), LDP Solenoid Electrical Malfunction

Description
When the ignition switch is turned to ON, the PCM checks for DTC 183.
DTC 183 can be set under any of the following conditions:
- Open or short in the LDP solenoid wiring
- Electrical fault in the LDP solenoid
- PCM failure

DTC 183 Diagnosis




IMPORTANT: Before beginning this procedure, repair all vehicle conditions for DTCS that are not related to the EVAP system except DTC 18. If more one EVAP system DTC is set, diagnose and repair in the following order:
1. DTC 183
2. DTC 184
3. DTC 187
4. DTCs 160/161

1. Connect the scan tool and adapter harness MB991545.
2. Turn the ignition switch to ON.




3. Activate the LDP solenoid by following the scan tool sequence shown in the illustration at left.
4. Listen for a repeating clicking noise from the LDP, which indicates the LDP solenoid is operational.
a. If a clicking noise is heard, the LDP solenoid is functioning and the condition that caused DTC 183 to set may not be present at this time. Try to duplicate the condition by inspecting the associated wiring harness and connectors for signs of damage. Repair or replace the wiring harness as necessary. Then go to the Readiness Test. 48 Readiness Test
b. If a clicking noise not heard, there is a concern with the LDP circuit or its components. Go to Step 5.
5. Inspect the LDP connector E-40 and its terminal. Check for corrosion, bent pins, backed out pins, etc.
a. If no damage is found, go to Step 6.
b. If damage is found, repair or replace as necessary. Clear all DTCs, then start the engine and recheck for DTCs.
6. Enter LDP Hold Mode to activate the LDP solenoid for the voltage testing in this procedure.




To enter LDP Hold Mode, follow the scan tool selection sequence shown in the illustration at left.




7. Using a voltmeter, test for voltage between terminal 2 (B W) of LDP connector E-40 and ground. Do not disconnect the connector. Backprobe at terminal 2. The voltage reading should be within one volt of battery voltage.
a. If within one volt of battery voltage, this indicates that the voltage supply to terminal 2 is OK. Go to Step 8.
b. If not within one volt of battery voltage, the voltage supply to the LDP is not sufficient to activate the LDP solenoid. Repair or replace the wiring harness as necessary. Then go to the Readiness Test. 48 Readiness Test




8. Using a voltmeter, test for voltage between terminal 3 (red/yellow) of LDP connector E-40 and ground. Do not disconnect the connector. Backprobe at terminal 3.
a. If the voltage reading is less than one volt, there is no problem in the internal LDP solenoid circuit. Go to Step 13.
b. If the voltage reading is more than one volt, this indicates that either the PCM wiring or the PCM itself is not providing proper ground for the LDP solenoid. Go to Step 9.




9. Turn the ignition switch to OFF. Disconnect PCM connector A-78 and inspect terminal 77 for damage and corrosion.
a. If damage or corrosion is found, repair or replace the wiring harness as necessary. Then go to the Readiness Test. 48 Readiness Test
b. If no damage or corrosion is found, go to Step 10 for further LDP circuit inspection to determine why the LDP solenoid is not operating.
10. Disconnect LDP connector E-40. Measure the resistance between terminal 77 of PCM connector A-78 and terminal 3 of LDP connector E-40.
a. If the resistance reading is less than one ohm, go to Step 11.
b. If the resistance reading is one ohm or greater, inspect connectors E-40, E08, E41 and A-78, and the associated wiring. Repair or replace the wiring harness as necessary. Then go to the Readiness Test. 48 Readiness Test




11. Reconnect LDP connector E-40. Turn the ignition switch to ON. Place your hand on the LDP. Ground terminal 77 of the PCM connector A-78 with a jumper wire. You should feel a light tapping as the LDP solenoid activates.
a. If the LDP solenoid does not activate and Steps 1-10 of this procedure were properly performed, the LDP solenoid has internally failed. Go to Step 12.
b. If the LDP solenoid activates, clear DTCs and recheck for DTC 183.
1. If DTC 183 is reset, this indicates that the PCM cannot ground the LDP circuit. Replace the PCM. Then go to the Readiness Test. 48 Readiness Test
2. If DTC 183 is not reset, the problem is intermittent. Contact Tech Line for further troubleshooting instructions.




12. With the ignition switch turned to ON, enter LDP Hold Mode as described in Step 6. Connect a test light to B+ and probe terminal 3 of LDP connector E-40.
a. If the test light illuminates, replace the LDP. Then go to the Readiness Test. 48 Readiness Test
b. If the test light does not illuminate, replace both the LDP and the PCM. Then go to the Readiness Test. 48 Readiness Test




13. (From Step 8a.) Turn the ignition switch to OFF. Disconnect LDP connector E-40. Check the resistance of the LDP circuit by connecting one lead of the DVOM to terminal 77 (red/yellow) of PCM connector A-78 and the other DVOM lead to ground.
a. If the resistance reading is infinite, go to Step 14.
b. If the resistance reading is not infinite, this indicates there is a short to ground. Repair or replace the wiring harness as necessary. Then go to the Readiness Test. 48 Readiness Test




14. The ignition switch should be OFF and LDP connector E-60 disconnected. Using a DVOM, replace one lead on terminal 2 and the other lead on terminal 3 of the LDP.

NOTE: The LDP resistance specification depends on the LDP part number (located on top of the LDP):
- For LDPs with part number 4669306K or 4669306L, the resistance reading should be 20-30 ohms.
- For LDPs with part number 4669306AB, the resistance reading should be 12-20 ohms.
a. If the resistance reading is within specification, go to Step 15.
b. If the resistance reading is not within specification, replace the LDP for internal solenoid failure. Then go to the Readiness Test. 48 Readiness Test
15. Reconnect LDP connector E-40 and PCM connector A-78. Clear DTC 183 and recheck for diagnostic trouble codes. If DTC 183 resets, replace the PCM. Then go to the Readiness. 48 Readiness Test