Diagnostic Procedure

WARNING: This page is about a different car, the 2005 Jeep Liberty. However, it is still accessible from the selected car via links, so may be relevant.

P0888-RELAY OUTPUT ALWAYS OFF DIAGNOSTIC TEST REFERENCE

TEST	ACTION	APPLICABILITY
1	NOTE: Low fluid level can be the cause of many transmission problems. If the fluid level is low locate and repair the leak then check and adjust the fluid level per the Service Information. NOTE: Always perform diagnostics with a fully charged battery to avoid false symptoms. With the DRBIII®, read Engine DTC's. Check and repair all Engine DTC's prior to performing any transmission symptom diagnostics.With the DRBIII®, read Transmission DTC's. Record all DTC's and 1 Trip Failures. NOTE: Diagnose 1 Trip Failures as a fully matured DTC. Using the wiring diagram/schematic as a guide, inspect the wiring and connectors.Repair as necessary.Perform the Shift Lever Position Test. If the test does not pass, refer to Symptom test for P0706 CHECK SHIFTER SIGNAL .For Gear Ratio DTC's, check and record all CVI's.Most DTC's set on start up but some must be set by driving the vehicle such that all diagnostic monitors have run. NOTE: Verify flash level of Powertrain Control Module. Some problems are corrected by software upgrades to the Transmission and Engine software. NOTE: Check for applicable TSB's related to the problem. Perform this procedure prior to Symptom diagnosis.ContinueGo To 2	All
2	With the DRBIII®, Check the STARTS SINCE SET counter for P0888. NOTE: This counter only applies to the last DTC set. Is the STARTS SINCE SET counter equal to 0? Yes --> Go To 3 No --> Go To 13	All
3	Turn the ignition off to the lock position. Remove the Transmission Control Relay. NOTE: Check connectors - Clean/repair as necessary. Using a 12-volt test light connected to ground, check the Fused B+ circuit in the Transmission Control Relay connector. NOTE: The test light must illuminate brightly. Compare the brightness to that of a direct connection to the battery. Does the test light illuminate brightly? Yes --> Go To 4 No --> Go To 10	All
4	Turn the ignition off to the lock position. Remove the Transmission Control Relay. NOTE: Check connectors - Clean/repair as necessary. Connect a jumper wire between the Fused B+ circuit and the Transmission Control Relay Output circuit. Ignition on, engine not running. With the DRBIII® in Transmission Sensors, read the Switched Battery voltage. Does the Switched Battery voltage read battery voltage? Yes --> Go To 5 No --> Repair the Transmission Control Relay Output circuit for an open or high resistance. Note: There are multiple Transmission Control Relay Output circuits. Perform 42RLE (NGC) TRANSMISSION VERIFICATION TEST - VER 1 .	All
5	Turn the ignition off to the lock position. Install a substitute Relay in place of the Transmission Control Relay. Ignition on, engine not running. With the DRBIII® in Transmission Sensors, read the Switched Battery voltage. Does the Switched Battery voltage read battery voltage? Yes --> Replace the Transmission Control Relay. Perform 42RLE (NGC) TRANSMISSION VERIFICATION TEST - VER 1 . No --> Go To 6	All
6	Turn the ignition off to the lock position. Remove the Transmission Control Relay. NOTE: Check connectors - Clean/repair as necessary. Using a 12-volt test light connected to 12-volts, check the Transmission Control Relay Ground circuit. NOTE: The test light must illuminate brightly. Compare the brightness to that of a direct connection to the battery. Does the test light illuminate brightly? Yes --> Go To 7 No --> Repair the Transmission Control Relay Ground circuit for an open. Perform 42RLE (NGC) TRANSMISSION VERIFICATION TEST - VER 1 .	All
7	Turn the ignition off to the lock position. Remove the Transmission Control Relay. Disconnect the PCM harness connector. NOTE: Check connectors - Clean/repair as necessary. CAUTION: DO NOT PROBE THE PCM HARNESS CONNECTORS. PROBING THE PCM HARNESS CONNECTORS WILL DAMAGE THE PCM TERMINALS RESULTING IN POOR TERMINAL TO PIN CONNECTION. INSTALL MILLER SPECIAL TOOL #8815 TO PERFORM DIAGNOSIS. Measure the resistance of the Transmission Control Relay Control circuit between the Transmission Control Relay connector and the appropriate terminal of special tool #8815. Is the resistance above 5.0 ohms? Yes --> Repair the Transmission Control Relay Control circuit for an open. Perform 42RLE (NGC) TRANSMISSION VERIFICATION TEST - VER 1 . No --> Go To 8	All
8	Turn the ignition off to the lock position. Disconnect the PCM harness connector. Remove the Transmission Control Relay. NOTE: Check connectors - Clean/repair as necessary. CAUTION: DO NOT PROBE THE PCM HARNESS CONNECTORS. PROBING THE PCM HARNESS CONNECTORS WILL DAMAGE THE PCM TERMINALS RESULTING IN POOR TERMINAL TO PIN CONNECTION. INSTALL MILLER SPECIAL TOOL #8815 TO PERFORM DIAGNOSIS. Measure the resistance between ground and the Transmission Control Relay Control circuit. Is the resistance below 5.0 ohms? Yes --> Repair the Transmission Control Relay Control circuit for a short to ground. Perform 42RLE (NGC) TRANSMISSION VERIFICATION TEST - VER 1 . No --> Go To 9	All
9	Using the schematics as a guide, inspect the wiring and connectors. Repair as necessary. Pay particular attention to all power and ground circuits. If there are no possible causes remaining, view repair. Repair Replace the Powertrain Control Module per the Service Information. WITH THE DRBIII® PERFORM QUICK LEARN . Perform 42RLE (NGC) TRANSMISSION VERIFICATION TEST - VER 1 .	All
10	Turn the ignition off to the lock position. Remove the Transmission Control Relay. Disconnect the PCM harness connectors. NOTE: Check connectors - Clean/repair as necessary. CAUTION: DO NOT PROBE THE PCM HARNESS CONNECTORS. PROBING THE PCM HARNESS CONNECTORS WILL DAMAGE THE PCM TERMINALS RESULTING IN POOR TERMINAL TO PIN CONNECTION. INSTALL MILLER SPECIAL TOOL #8815 TO PERFORM DIAGNOSIS. Measure the resistance between ground and the Transmission Control Relay Output circuit. Is the resistance below 5.0 ohms? Yes --> Go To 11 No --> Repair the Fused B+ circuit for an open. Perform 42RLE (NGC) TRANSMISSION VERIFICATION TEST - VER 1 .	All
11	Turn the ignition off to the lock position. Disconnect the PCM harness connector. Disconnect the Transmission Solenoid/Pressure Switch harness connector. Remove the Transmission Control Relay. NOTE: Check connectors - Clean/repair as necessary. CAUTION: DO NOT PROBE THE PCM HARNESS CONNECTORS. PROBING THE PCM HARNESS CONNECTORS WILL DAMAGE THE PCM TERMINALS RESULTING IN POOR TERMINAL TO PIN CONNECTION. INSTALL MILLER SPECIAL TOOL #8815 TO PERFORM DIAGNOSIS. Measure the resistance between ground and the Transmission Control Relay Output circuit. Is the resistance below 5.0 ohms? Yes --> Repair the Transmission Control Relay Output circuit for a short to ground. Perform 42RLE (NGC) TRANSMISSION VERIFICATION TEST - VER 1 . No --> Go To 12	All
12	Using the schematics as a guide, inspect the wiring and connectors. Repair as necessary. Pay particular attention to all power and ground circuits. If there are no possible causes remaining, view repair. Repair Replace the Transmission Solenoid/Pressure Switch Assembly per the Service Information. Perform 42RLE (NGC) TRANSMISSION VERIFICATION TEST - VER 1 .	All
13	he conditions necessary to set the DTC are not present at this time. Using the schematics as a guide, inspect the wiring and connectors specific to this circuit. Wiggle the wiring and connectors while checking for shorted and open circuits. With the DRBIII®, check the EATX EVENT DATA to help identify the conditions in which the DTC was set. Were there any problems found? Yes --> Repair as necessary. Perform 42RLE (NGC) TRANSMISSION VERIFICATION TEST - VER 1 . No --> Test Complete.	All