Ford calls the transmission control processor the 'Electronic Control Assembly', or ECA. However, the unit can be interpreted as a modern transmission control module, or TCM. The ECA controls transmission shift timing, regulates transmission line pressure, controls the torque converter lockup sequence, and provides certain diagnostics. In gasoline applications, the ECA controls electronic functions for both the engine and transmission. In diesel applications, however, the ECA acts as a stand-alone controller for the transmission and does not play a role in engine function.
While the E4OD remained the only automatic transmission available behind the Power Stroke diesel through the 1998 model year, it may be necessary to distinguish the E4OD from the lighter duty AOD/AODE in gasoline applications. This is easily accomplished by examining the shift sequence:
AOD, AODE shift pattern: P-R-N-OD-D-1
E4OD shift pattern: P-R-N-OD-2-1
Note that the fundamental difference is in the "D" position found on the AOD opposed to the "2" position found on the E4OD. There may be exceptions to this rule, however it should hold true for all F-Series pickup and Bronco applications. The E4OD would eventually be replaced by the 4R100, which essentially represents Ford's transition to an alternative name convention for drivetrain products, as the transmission is similar to, but not interchangeable with the E4OD. The 4R100, however, represents changes, upgrades, and improvements necessary for Ford's automatic transmission platform to pace the quickly evolving F-Series diesel program.
E4OD Transmission Ratios
| 1st | 2nd | 3rd | 4th | R |
| 2.71 : 1 | 1.538 : 1 | 1.00 : 1 | 0.71 : 1 | 2.18 : 1 |
Ford E4OD Transmission Specs
| Transmission | Ford E4OD | |
| Type | 4 speed automatic overdrive transmission | |
| Predecessor | Ford C-6 | |
| Model Years/Applications | 1989 - 1998 Ford F-Series | |
| Case Material | Aluminum | |
| Max Input Torque | N/A | |
| Weight | ~ 270 lbs w/ torque converter | |
| ATF Type/Spec[1] | Ford MERCON V automatic transmission fluid | |
| Transmission Filter P/N | 2WD applications | Motorcraft FT-113 |
| 4WD applications | Motorcraft FT-114 | |
| Fluid Capacity | ~ 17 - 18 quarts | |
| Service Intervals | Replace automatic transmission fluid and filter at 30,000 mile intervals. | |
| Features | • Relatively high transmission fluid capacity • Fully electronic shift and fluid pressure control systems (5 electric shift solenoids) • Standalone transmission control module (ECA) in diesel engine applications |
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[1] The original fluid spec for the E4OD automatic transmission was MERCON automatic transmission fluid; this fluid has been discontinued and replaced by MERCON V.
A flashing "OD" light on the shift lever of an E4OD equipped pickup indicates that the ECA has detected a transmission problem and is alerting the driver to take the vehicle in for diagnostics, service, and/or repair. The E4OD was improved multiple times over the course of its existence - when overhauling the E4OD, consult with your transmission expert to ensure you receive any and all updated components that may provide favorable reliability and durability.