P1600

Diagnostic Chart:

Wiring Diagram:

CIRCUIT DESCRIPTION

The Shift Solenoids, the Band Apply Solenoid, and the TCC Solenoid are supplied power via the Transmission Power Relay (internal to the Transmission Control Module (TCM)) on TCM pin 54. The Pressure Control Solenoid is also supplied power via the Transmission Power Relay (internal to the TCM) but on TCM pin 40. TCM pins 54 and 40 are connected within the TCM. The TCM controls the solenoids by grounding the appropriate control circuit via internal solid state devices called drivers. The driver circuits have their own fault detection abilities that identify problems with individual solenoids/circuits. The TCM also has fault detection circuitry for the power supply circuit that powers all of the solenoids in the transmission. If the TCM detects a problem with this circuit, DTC P1600 will set, and the TCM will shut off the Transmission Power Relay. Any time a TCM DTC is set that requires the transmission to operate in Default Mode, the TCM turns off the power relay, effectively disabling all of the transmission solenoids. Any time the Default Mode is in effect, the transmission line pressure is at maximum, and the transmission starts in 4th gear.

CONDITIONS FOR RUNNING THE DTC

Tests continuously

CONDITIONS FOR SETTING THE DTC

A short to ground, open circuit, or short to battery voltage detected on the control circuit.

ACTION TAKEN WHEN THE DTC SETS

^ The TCM illuminates the Service Transmission Lamp (STL) and sends a Malfunction Indicator Lamp (MIL) Request to the ECM on the second consecutive drive trip that the diagnostic runs and fails. The ECM then illuminates the MIL.

^ The ECM records the operating conditions in the Freeze Frame at the time of the MIL Request from the TCM.

^ The transmission operates in the Default Mode.

CONDITIONS FOR CLEARING THE MIL/DTC

^ The TCM turns off the STL as soon as the fault is no longer present.

^ The ECM turns off the MIL after three consecutive drive trips during which the TCM sends no MIL Request.

^ A History DTC clears after forty consecutive warm-up cycles, if no failures are present by this diagnostic or any other emission related diagnostic.

^ The scan tool clears the MIL/DTC.

DIAGNOSTIC AIDS

Use the Connector Test Adapter Kit J 35616-A for any test that requires probing the TCM harness connector or a component harness connector. Using this kit will prevent damage to the harness connector terminals.

Check for the following conditions:

^ Poor connections at the TCM or at the component. Inspect the harness connectors for any backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and poor terminal to wire connection. Refer to Overall Vehicle Information / Diagrams / Diagnostic Aids for Checking Terminal Contact procedure.

^ Damaged harness. Inspect the wiring harness for damage. If the harness appears to be OK, observe the scan tool while moving any related connectors and any wiring harnesses. A change in the display may help to locate the fault.

TEST DESCRIPTION

The number(s) below refer to the step numbers on the diagnostic table.

2. Allows the TCM to determine if the fault is present now.

7. This test determines if the Transmission Power Relay output circuit is open between the TCM and the splice. For this DTC to set from an open circuit, the open would have to be between the TCM and the splice. An open in either of the circuits after the splice would set DTCs for the affected solenoids only.