Automatic Transmission - Diagnosis - CD4E: Overview Mercury Cougar VIII

DESCRIPTION & OPERATION

The first step in diagnosing any driveability concern is verifying the customer's complaint with a test drive under the conditions the concern reportedly occurred. Before entering self-diagnostics, perform a careful and complete visual inspection. Most transmission control concerns result from mechanical breakdowns or poor electrical connections.

Input signals from sensors are sent to the Powertrain Control Module (PCM). (Scheme 52) The PCM controls shifts and converter clutch application. The PCM can also determine line pressure needed to optimize shift feel.

Other inputs are based on driver inputs, such as accelerator pedal position, which is relayed to the PCM via Throttle Position (TP) sensor. Inputs are provided by the transaxle itself, from sensors such as Vehicle Speed Sensor (VSS), Transmission Range (TR) sensor, and Transmission Fluid Temperature (TFT) sensor. All of these input signals allow the PCM to determine when time and conditions are right for a shift or converter clutch application.

Five electronic solenoids accomplish the following functions

1. 2 on/off solenoids for shifting.
2. One Pulse-Width Modulator (PWM) solenoid for Torque Converter Clutch (TCC) control.
3. One Variable Force Style (VFS) Electronic Pressure Control (EPC) solenoid for line pressure control.
4. One Variable Force Style (VFS) 3-2 timing/coast clutch solenoid to control release of coast clutch, coordinated release of the direct clutch, and apply of the low and intermediate band.

PCM has built-in self-diagnosis, fail-safe code and warning code display for the main input sensors and solenoid valves.

Scheme 52

Description

The following procedures are functional tests of EEC-V system. These basic test steps must be followed in sequence to avoid misdiagnosis

1. «VISUAL CHECK»(ref-11799-S42072295712000112900000)
2. «EQUIPMENT HOOKUP»(ref-11799-S07575784592000112900000)
3. «KEY ON ENGINE OFF (KOEO) SELF-TEST»(ref-11799-S15028541862000112900000)
4. «KEY ON ENGINE RUNNING (KOER) SELF-TEST»(ref-11799-S03301190092000112900000)

After each service or repair procedure has been completed, repeat QUICK TEST to ensure all EEC-V systems operates properly and DTCs are no longer present.