Solenoids
The solenoid valves are some of the outputs of the Transmission ECU. These solenoids are the proportional type. The ECU uses a pulse width modulated signal (PWM) to vary the current to the solenoid. The distance that is Traveled by the solenoid valve is proportional to the electrical current. The position of the valve controls the flow of the oil to the hydraulic cylinder.
Transmission Shift Solenoids
 | |
| Illustration 1 | g01237747 |
The solenoid will work for either 12 V or 24 V systems. The medium 12 V ECPC valve will be used for all transmission clutches and the lockup clutch on the OEM On-highway truck transmissions. This solenoid valve is driven by a pulse width modulated signal from the ECU.
When a clutch solenoid is shorted to ground or an opened circuit, then all gears that use that clutch are not available. If a clutch solenoid is shorted to +battery, then only gears with that clutch are available. If more than one clutch is shorted to +battery, then the control cannot do anything and goes to no clutch neutral until fixed. Whenever a clutch solenoid has failed, the lockup clutch is turned off.
The software will keep a list of available gears when a diagnostic trouble code occurs. If the control lever selects neutral, then the only way to get back to a selected gear is by shifting to neutral and then back into gear. For example, if the transmission is in reverse and clutch 3 is an opened circuit, then the transmission shifts to neutral and stays there until the operator selects neutral and reselects either forward or reverse. When a diagnostic trouble code occurs, if the current gear is available, then the control will remain in that gear. But if the diagnostic trouble code is present on an active clutch, then the software has to determine the appropriate desired gear. When a diagnostic trouble code goes active, the default logic will pick the next available lower gear as long as the output speed does not exceed the maximum output speed allowed for that gear. If a lower gear is not available or the output speed is too high for that gear, then select the next higher gear available.
Transmission Lockup Clutch Solenoid
| | |
| Illustration 2 | g01237747 |
The Transmission ECU uses the solenoid valve to directly modulate the oil pressure to each transmission clutch. The ECU uses a pulse width modulated signal in order to vary the current to the solenoid. The solenoid current determines the amount of oil pressure that is applied to each clutch. The travel distance of the solenoid plunger is proportional to the amount of electrical current that is being sent to the solenoid. The position of the solenoid plunger controls the amount of oil pressure and the amount of clutch engagement. An increase in the electrical current will open the solenoid valve further. This causes and increase in oil pressure.
The transmission lockup clutch solenoid connects to the ECU at contact J1-60 and contact J1-62.
Output Drivers
Note: If you are experiencing problems with a driver that has been replaced, see Symptom Troubleshooting, KENR5099, "Replaced Relay or Solenoid Does Not Operate".
Starter Interlock Driver
The driver has the ability to drive up to two amps. For the electrical connections, see Testing and Adjusting, KENR5099, "System Schematic".
Output Speed Driver
The driver has the ability to drive up to 300 milliamps. The output is for driving the speedometer in the dash. For the electrical connections, see Testing and Adjusting, KENR5099, "System Schematic". The +battery contact of the speedometer connects at the positive battery terminal.
Speed Enable Driver
The possibilities of the driver include controlling a steerable axle feature, an automatic lowering of the chassis, or preventing a door from opening until the vehicle is stopped. This feature can be programmed to monitor one of three different speeds. The three speeds are the engine speed, PTO engine speed, and the transmission output speed. The feature monitors the engine speed that is broadcast over J1939 data link when the relay is programmed to the engine speed. The ECU monitors the transmissions PTO shaft speed when the relay is programmed to the PTO engine speed. The ECU monitors the output shaft speed of the transmission when the driver is programmed to the transmission output speed. The driver connects to the ECU at contact J2-13. For the electrical connections, see Testing and Adjusting, KENR5099, "System Schematic".
Gear Output Driver
For the electrical connections, see Testing and Adjusting, KENR5099, "System Schematic".