DTC P1625 TCM System Reset. Cadillac Catera 1998

For 1990-2009 cars only

Makes 🢒 Cadillac 🢒 1998 🢒 Catera 🢒 DTC 🢒 DTC P1625 TCM System Reset

Circuit Description

The TCM performs various internal tests. Some of these tests include checks on data integrity, memory performance, and the Transmission Power Relay control circuits. If the TCM detects a problem in any of these areas, a DTC will set.

Conditions For Running The DTC

Once at power up.

Conditions For Setting The DTC

The TCM detects an internal problem.

Action Taken When the DTC Sets

•	The TCM illuminates the Service Transmission Lamp (STL) 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.

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 Engine Electrical, Troubleshooting Procedures, Checking Terminal Contact 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 numbers below refer to the step numbers on the diagnostic table.

An intermittent short to B+ on the Power Relay output circuit can cause this DTC to set. Check the Power Relay output circuit for this intermittent condition before replacing the TCM.

DTC P1625 - TCM Internal Error

Step	Action	Value(s)	Yes	No
1	Was the Powertrain On-Board Diagnostic (OBD) System Check performed?	--	Go to Step 2	Go to Powertrain On Board Diagnostic (OBD) System Check
2	Turn off the ignition. Disconnect the TCM. Turn on the ignition with the engine off. Use the test light connected to ground in order to probe the Transmission Power Relay output circuit in the TCM harness connector. Does the test light illuminate?	--	Go to Step 3	Go to Step 4
3	Repair the Power Relay output circuit shorted to B+. Is the action complete?	--	Go to Step 5	--
4	Replace the TCM. Refer to Automatic Transmission, On Vehicle Service, TCM . Is the action complete?	--	Go to Step 5	--
5	Clear the scan tool. Turn off the ignition for 15 seconds. Start the engine. Operate the vehicle within the conditions required for this diagnostic to run. Refer to Conditions for Running the DTC. Check for any DTCs. Is DTC P1625 set?	--	Go to Step 2	Go to Step 6
6	Were there any additional DTCs noted during the Powertrain or Transmission OBD System Check that have not been diagnosed?	--	Go to the applicable DTC table	Go to Step 7
7	Does the Transmission now function properly?	--	System OK	Go to Functional Test