For 1990-2009 cars
Automatic Transmission Components
Automatic Transmission Controls Schematics
OBD II Symbol Description Notice
Handling ESD Sensitive Parts Notice

### Circuit Description

The shift solenoids, the band apply solenoid, and the TCC solenoid are supplied power via the transmission power relay (internal to the TCM) on TCM terminal 53. The pressure control solenoid is also supplied power via the transmission power relay (internal to the TCM) but on TCM terminal 52. TCM terminals 52 and 53 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 conditions 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 condition with this circuit, DTC P1800 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 components. Any time the default mode is in effect, the transmission line pressure is at maximum, the transmission starts in 4th gear, TCC is inhibited and the transmission adapt shift function is disabled.

When the TCM detects a power supply interrupt on TCM terminals 52 and 53, then DTC P1800 sets. DTC P1800 is a type B DTC.

### Conditions for Running the DTC

• | The ignition switch is in the RUN position.

• | No 1-2/3-4 SS valve DTC P0753.

• | No 1-2/3-4 SS valve DTC P0758.

• | No TCC enable solenoid circuit- Electrical DTC P0743.

• | No band apply solenoid circuit DTC P1850.

### Condition for Setting the DTC

Power supply to TCM terminals 52 and 53 is interrupted.

### Action Taken When the DTC Sets

• | The TCM flashes the sport mode lamp and sends a 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 (maximum line pressure, command 4th gear, inhibit TCC, freeze shift adapts).

### Conditions For Clearing the MIL/DTC

• | 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.

• | The TCM cancels the DTC default mode actions when the ignition switch is Off long enough in order to power down the TCM.

### Diagnostic Aids

Use the J 35616-A connector test adapter kit 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 General Electrical Diagnosis in Wiring Systems for proper 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 below refers to the step number on the Diagnostic Table.

1. 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.

#### DTC P1800 TCM Power Control Relay Circuit-Open

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | Go to Step 2 | Go to A Powertrain On Board Diagnostic (OBD) System Check
2 |

1. Turn the ignition switch to the OFF position.
2. Disconnect the TCM.
3. Turn the ignition switch to the ON position with the engine OFF.
4. With the J 35616-200 test light connected to ground, probe the transmission power relay output circuit (terminals 52 and 53) in the TCM harness connector.

Does the test light illuminate?

--

Go to Step 7

Go to Step 3

3 | With the J 35616-200 connected to B+, probe the transmission power relay output circuit (terminals 52 and 53) in the TCM harness connector. Does the test light illuminate? | -- | Go to Step 4 | Go to Step 6
4 |

1. Disconnect the adapter case harness connector.
2. With the J 35616-200 connected to B+, probe the transmission power relay output circuit (terminals 52 and 53) in the TCM harness connector.

Does the test light illuminate?

--

Go to Step 5

Go to Step 10

5 |

1. Disconnect the main case harness connector.
2. With the J 35616-200 connected to B+, probe the transmission power relay output circuit (terminals 52 and 53) in the TCM harness connector.

Does the test light illuminate?

--

Go to Step 8

Go to Step 11

6 | Use a J 39200 digital multimeter (DMM) in order to check the harness for continuity of the transmission power relay output circuit (terminals 52 and 53) from the TCM harness connector to either the Main Case or Adapter Case harness connector. Is continuity indicated? | -- | Go to Step 12 | Go to Step 9
7 | Repair the power relay output circuit shorted to B+. Is the action complete? | -- | Go to Step 13 | --
8 | Repair the power relay output circuit shorted to ground. Is the action complete? | -- | Go to Step 13 | --
9 | Repair the open/high resistance power relay output circuit. Is the action complete? | -- | Go to Step 13 | --
10 | Repair the transmission power relay output circuit shorted to ground in the adapter case. Is the action complete? | -- | Go to Step 13 | --
11 | Repair the transmission power relay output circuit shorted to ground in the main case. Is the action complete? | -- | Go to Step 13 | --
12 | Check the TCM harness connector for a poor connection or poor terminal tension. Refer to General Electrical Diagnosis in Wiring Systems. Was a condition found and corrected? | -- | Go to Step 13 | --
13 |

1. Clear the DTCs with the Scan Tool .
2. Turn the ignition switch to the OFF position for 15 seconds.
3. Start the engine.
4. Operate the vehicle to ensure all transmission solenoids are operating correctly.
5. Check for any transmission DTCs.

Is DTC P1800 set?

--

Go to Step 1

System OK