Part 1 of 3
NAME OF CODE: P0613(11, 13, or 45) - Internal ControllerWhen monitored: Whenever the key is in the Run or Run/Start position.
Set condition: This code is set whenever Transmission Control Module (TCM) senses an internal error
Theory of Operation: The TCM is constantly monitoring it's internal processor. If an internal problem is detected, this DTC will be set. This DTC can also be set by a bad ground to the TCM and/or Trans Control Relay.
Transmission Effects: The MIL will illuminate (this DTC can take up to five minutes of problem identification before illuminating the MIL) and the transmission system will default to the Immediate Shutdown routine.
Possible Causes:
^ TCM ground circuit.
^ Relay ground circuit
^ TCM
NAME OF CODE: P1684(12) - Battery was Disconnected (Informational code Only)
When Monitored: Whenever the key is in the Run/Start position.
Set Condition: This code is set whenever the Transmission Control Module (TCM) is disconnected from battery power (B+) or ground. It will also be set during the DRBIII Battery Disconnect procedure.
Theory of Operation: A battery backed RAM (Random Access Memory) is used to maintain some learned values. When the battery B(+) is disconnected, the memory is lost. When the B(+) is restored, this memory loss is detected by the TCM. The code is set and the learned values are initialized to known constants or previously learned values from EEPROM (Electronic Erasable Programmable Read Only Memory). This results in the reinitialization of some parameters.
Transmission Effects: Loss of trouble code data. Immediate Limp-in mode if power is lost while operating the vehicle. Normal operation is resumed if the power is restored during the same key start *
Possible Causes:
^ Battery voltage removed from TCM
^ TCM disconnected
^ Dead Battery
^ Low battery voltage during cranking
^ Battery Disconnect by DRBIII or MDS
^ Bad TCM ground circuit.
NAME OF CODE: P0891(14) - Transmission Relay Always On
When Monitored: Ignition key is turned from off position to run position and/or ignition key is turned from crank position to run position.
Set Condition: This code is set if the Transmission Control Module (TCM) senses greater than 3 volts at the Trans Relay Output (switched battery) terminal of the TCM prior to the TCM energizing the relay.
Theory of Operation: The transmission control relay is used to supply power to the solenoid pack when the transmission is in normal operating mode. When the relay is off, no power is supplied to the solenoid pack and the transmission is in Limp-in mode. The relay output is fed back to the TCM through pins 16 and 17. It is referred to as Trans Relay Output circuit or switched battery.
Transmission Effects: The MIL will illuminate and the transmission system defaults to Logical Limp-in mode. Logical Limp-in mode results in the same modes of operation as Limp-in. Since the relay is stuck "on", the TCM can not open the relay, and the TCM shifts to 2nd gear.
Possible Causes:
^ Relay failure (welded contacts)
^ Short to battery in 12-volt supply and/or Transmission Control Relay Output circuit(s)
^ Short to voltage
^ TCM connector problems
^ TCM
NAME OF CODE: P0888(15) - Relay Output Always Off
When Monitored: Continuously
Set Condition: This code is set when less than 3 volts are present at the Trans Relay Output (switched battery) terminals at the Transmission Control Module (TCM) when the TCM is energizing the relay.
Theory of Operation: The transmission control relay is used to supply power to the solenoid pack when the transmission is in normal operating mode. When the relay is off, no power is supplied to the solenoid pack and the transmission is in Limp-in mode. The relay output is fed back to the TCM through pins 16 and 17. It is referred to as the Trans Relay Output circuit or switched battery.
After a controller reset (ignition key turned to the run position or after cranking engine), the controller energizes the relay. Prior to this the TCM verifies that the contacts are open by checking for no voltage at the switched battery terminals. After the relay is energized, the TCM monitors the terminals to verify that the voltage is greater than 3 volts.
Transmission Effects: The MIL will illuminates and the transmission system defaults to Limp-in mode.
Possible Causes:
^ Relay failure (intermittent relay function caused by oxidized or contaminated relay contacts)
^ Short to ground or open circuit in the Trans mission Control Relay circuit(s)
^ TCM connector problem
^ TCM
NAME OF CODE: P0725(18) - Engine Speed Sensor Circuit
NOTE: This code is not a transmission input speed sensor DTC
When Monitored: Whenever the engine is running.
Set Condition: This code is set when the engine speed sensed by the Transmission Control Module (TCM) is less than 390 RPM or greater than 8000 RPM for more than 2.0 seconds.
Theory of Operation: The TCM uses either a EATX RPM signal (simulated Crank Sensor signal) or the TCM uses the Crank Position Sensor signal to calculate engine RPM depending on the engine application. The signal supplied by the PCM and uses a dedicated circuit is called the EATX RPM Signal circuit. The Crank Position sensor signal is a spliced circuit from the engine Crank Position Sensor. Check the wiring schematics to determine which (engine speed sensor circuit) is used in the vehicle. If the TCM interprets this signal to be out of range when the engine is running (as reported by the PCM over the bus) the code is set.
Transmission Effects: The MIL illuminates and the transmission system defaults to Limp-in mode.
Possible Causes:
^ Open or short in EATX RPM Signal circuit.
^ Open or short in Crank Position Sensor Signal circuit.
^ Open or short in Crank Position Sensor ground circuit.
^ TCM and/or PCM connector problems
^ TCM
^ PCM
NAME OF CODE: P1694(19) - Bus Communication with Engine Module
When Monitored: Continuously with key on.
Set Condition: If no PCI bus messages are received from the Powertrain Control Module (PCM) for 10 seconds.
Theory of Operation: The TCM communicates with the PCM using the PCI bus. It relies on certain information to function properly. The TCM continuously monitors the PCI bus to check for messages broadcast from the PCM.
Transmission Effects: Delayed 3-4 shifts. No EMCC and early 3-4 shifts for a few minutes after engine is started.
Possible Causes:
^ Open or shorted PCI bus circuit
^ TCM
^ PCM
NAME OF CODE: P0890(20) - Switched Battery
When Monitored: Ignition key is turned from off position to run position and/or ignition key is turned from crank position to run position.
Set Condition: This code is set if the Transmission Control Module (TCM) senses voltage on any of the pressure switch inputs prior to the TCM energizing the relay.
Theory of Operation: The transmission control relay is used to supply power to the solenoid pack when the transmission is in normal operating mode. When the relay is off, no power is supplied to the solenoid pack and the transmission is in Limp-in mode. The relay output is fed back to the TCM through pins 16 and 17. It is referred to as the Trans Relay Output circuit or a switched battery.
Immediately after a controller reset (ignition key turned to the run position or after cranking engine), the TCM verifies that the relay contacts are open by checking for no voltage at the switched battery terminals. After this is verified, the voltage at the Solenoid Pack pressure switches is checked. There should be no voltage on the pressure switches at this time. The TCM will then activate the relay.
Transmission Effects: The MIL illuminates and the transmission system defaults to Limp-in mode.
Possible Causes:
^ Short to battery on one or more pressure switch sense circuits
^ TCM connector problems
^ TCM
NAME OF CODE: P0871(21) - OD Pressure Switch Sense Circuit
When Monitored: Whenever the engine is running.
Set Condition: This code is set if the OD pressure switch is open or closed at the wrong time in a given gear (see chart below).
Theory of Operation: The Transmission system uses three pressure switches to monitor the fluid pressure in the LR, 2/4, and OD clutch circuits. The pressure switches are continuously monitored for the correct states in each gear as shown.
Transmission Effects: Normal operation will be experienced if no other codes are present. TCM will ignore the code. Limp-in condition will only occur if code P0871(21) is present with a code P0706(28).
Possible Causes:
^ If code P0944(35) is present, ignore code P0871(21) and perform code P0944 diagnostic procedures
^ OD pressure switch sense circuit open or shorted to ground between TCM and solenoid pack
^ OD pressure switch sense circuit shorted to battery
^ Solenoid pack
^ Loose valve body bolts
^ Plugged filter - internal transmission or torque converter failure
^ TCM
NAME OF CODE: P0846(22) - 2/4 Pressure Switch Sense Circuit
When Monitored: Whenever the engine is running.
Set Condition: This code is set if the 2/4 pressure switch is open or closed at the wrong time in a given gear (see chart below).
41TE Pressure Switch States:
