Overview
The diagnostic process for each transmission concern will vary depending on the symptoms and condition of the vehicle. The diagnostic process below is an efficient method to collect as much data as possible about the concern before performing a repair or removing the transmission from the vehicle for teardown and further inspection. Intermittent concerns and concerns that result in default or fail-safe operations can be difficult to diagnose.
Automatic Transmission Diagnosis
Many transmission faults will set one or more diagnostic trouble codes (DTCs) in the PCM / TCM . In some instances a group of diagnostic trouble codes (DTCs) may indicate a particular fault. The transmission may only operate in default or failsafe modes while certain diagnostic trouble codes (DTCs) are set.
Begin diagnosis by carrying out the PCM self-tests: KOEO and CMDTC and KOER and CMDTC . Record all diagnostic trouble codes (DTCs) and related freeze frame data. Clear the diagnostic trouble codes (DTCs) after recording the information.
Preliminary Inspection
The preliminary inspection will:
PID Monitor/record on Road Test
Using the diagnostic trouble codes (DTCs) and freeze frame data as a guide, prepare the scan tool to make a recording of the event. Select the transmission parameter identifications (PIDs) that are related to the concern as well as parameter identifications (PIDs) for general automatic transmission operation. Since you may only get one or two chances to duplicate the concern, it is better to have more data on the recording. If possible, set datalogger to automatically start recording when a PID reaches a certain value. For example, you might want the recording to start 6 seconds before a fault PID changes from No Fault to Fault.
The PCM / TCM may set a DTC after the first occurrence of the fault. Some diagnostic trouble codes (DTCs) may require up to 5 consecutive occurrences before setting. Drive the vehicle in a manner similar to the freeze frame data conditions if possible. If no freeze frame data is available, then perform this road test:
After
the road test, review the recording and check for newly set diagnostic
trouble codes (DTCs). Electrical fault diagnostic trouble codes (DTCs)
are diagnosed in pinpoint tests. Hydraulic, mechanical, and performance
fault diagnostic trouble codes (DTCs) are diagnosed in component tests.
Use the DTC chart for detailed diagnosis:
REFER
to: Diagnostic Trouble Code (DTC) Charts and Pinpoint Tests - 3.3L
Duratec-V6 (307-01 Automatic Transmission - 6-Speed Automatic
Transmission – 6R80)
.
REFER to: Diagnostic Trouble Code (DTC) Charts and Pinpoint Tests - 3.5L Duratec (209kW/284PS) (307-01A)
.
REFER to: Diagnostic Trouble Code (DTC) Charts and Pinpoint Tests - 3.5L EcoBoost (272kW/370PS) (307-01A)
.
REFER to: Diagnostic Trouble Code (DTC) Charts and Pinpoint Tests - 5.0L 32V Ti-VCT (307-01A)
.
If no diagnostic trouble codes (DTCs) are set, use the data collected, the clutch application chart and the solenoid application chart to determine suspect transmission systems for the concern. Use the component test to diagnose each suspect system.
Pinpoint Tests
The pinpoint tests are divided by component or system. Each test is a series of circuit checks to verify the integrity of the wiring harness between the PCM / TCM and the solenoid or sensor.
Component Tests
The component tests are divided by system. Each test lists the possible symptoms the system can exhibit. For each symptom is a list of components that could cause the symptom. The components are listed in least intrusive to most intrusive order.
Perform Repair
An automatic transmission contains over 400 individual components. All of these components must be in good working order. Many repairs are fairly straightforward. In these repairs you will:
In the case of clutch failure where the transmission fluid is heavily contaminated with friction material, the transmission needs to be overhauled. The repair requires complete disassembly and cleaning of the transmission. All seals and gaskets (except the reusable pan gaskets) should be replaced.
Complete Repair
After reassembling the transmission, the following steps must be performed before returning the vehicle to the customer.