Component Tests and General Diagnostics

PRE-DIAGNOSTIC TROUBLE SHOOTING PROCEDURE-48RE GAS

1. NOTE: Always perform diagnostics with a fully charged battery to avoid false symptoms.

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.

With the scan tool, read engine DTC's. Check and repair all engine DTCs prior to performing transmission symptom diagnostics.
Using the wiring diagram/schematic as a guide, inspect the wiring and connectors. Repair as necessary.
Verify the flash level of the Powertrain Control Module. Some problems are corrected by software upgrades.
Check for any Service Information Tune-ups or Technical Service Bulletins that may apply.
Did any of the above checks or procedures correct the symptom?
Yes >> Repair is complete.
Perform RE TRANSMISSION VERIFICATION TEST VER-1 (GAS). 48RE Automatic Transmission - Gas
No >> Perform the appropriate symptom(s).