About Diagnostic Trouble Codes

DIAGNOSTIC TROUBLE CODES (DTC'S)
Always begin diagnosis by performing Test 1A-Entering Diagnostic Tests. This test will lead you through a visual inspection, the system test, reading the DTC's, and direct you to the specific test(s) that must be performed. If more than one code exists, diagnostic priority should be given to the most recent code.

If there is a CCD bus bias or communication problem, trouble codes will not be accessible until the problem is fixed. The DRB will display an appropriate message. The following is a possible list of causes for a bus problem:
- open or short to ground/battery in either or both CCD bus wires (pins 4 and 43)
- internal failure of any module or component on the bus

NOTE: The CCD bus should have approximately 2.5 volts on both wires.

For more detailed information about diagnosing CCD bus problems, refer to the appropriate Body Diagnostic Procedures.

Each diagnostic trouble code is diagnosed by following a specific testing sequence. The diagnostic test procedures contain step-by-step instructions for determining the cause of a transmission diagnostic trouble code. Possible sources of the code are checked and eliminated one by one. It is not necessary to perform all of the tests in this book to diagnose an individual code. In certain test procedures within this book, codes are used as a diagnostic tool.

DTC's which affect vehicle emissions will illuminate the Malfunction Indicator Lamp (MIL). Three consecutive successful OBDII trips or clearing the DTC's with a diagnostic tool (DRBIII or equivalent) is required to extinguish the MIL.

HARD CODE
Any diagnostic trouble code that comes back within three OBDII trips is a "hard" code. This means that the problem is there every time the TCM checks that circuit or function.

INTERMITTENT CODE
A diagnostic trouble code that is not there every time the TCM checks the circuit or function is an "intermittent" code. Problems that come and go like this are the most difficult to diagnose, they must be looked for under the specific conditions that cause them.

RESET COUNTER
For the most recent code (Code 1), the global good trip counter counts the number of times the vehicle has started since it was last set. The reset counter will count up to 255 starts.

When there are no diagnostic trouble codes stored in memory, the DRB will display "NO DTC's DETECTED".

If DTC's are detected, the DRB will display the number of global good trips. This is the number of good trips since the latest DTC was set. The number of global good trips helps determine if the diagnostic trouble code is hard or intermittent.
- If the reset code is 0, the code is a hard code.
- If the reset code is greater than 0, it is considered an intermittent code. This means that the transmission has been driven at least once without the code recurring.

TROUBLE CODE ERASURE
A diagnostic trouble code will be cleared from TCM memory if it has not reset for 40 warm-up cycles. A warm-up cycle is defined by CARB as "sufficient vehicle operation such that the coolant temperature has risen by at least 40OF from engine starting and reaches a minimum temperature of 160°F."

The Malfunction Indicator Lamp (MIL) will turn off after 3 good trips or when the DTC's are cleared from the TCM.

LIST OF DIAGNOSTIC TROUBLE CODES
The TCM may report any of the following DTC's.

Decimal Hex Scan Tool Name of Code
176 $B0 P1745 SOLENOID #1 SHORTED TO VOLTAGE
177 $B1 P1744 SOLENOID #1 SHORTED TO GROUND
178 $B2 P0751 SOLENOID #1 FUNCTIONAL FAULT
179 $B3 P1747 SOLENOID #2 SHORTED TO VOLTAGE
180 $B4 P1746 SOLENOID #2 SHORTED TO GROUND
181 $B5 P0756 SOLENOID #2 FUNCTIONAL FAULT
182 $B6 P1749 TCC SOLENOID SHORTED TO VOLTAGE
183 $B7 P1748 TCC SOLENOID SHORTED TO GROUND
184 $B8 P0740 TCC SOLENOID FUNCTIONAL FAULT
185 $B9 P0715 INPUT SPEED SENSOR
186 $BA P0720 OUTPUT SPEED SENSOR
187 $BB P0122 THROTTLE POSITION SENSOR SIGNAL CIRCUIT
188 $BC P0705 CHECK SHIFTER SIGNAL
190 $BE P1694 CCD MESSAGE FROM JTEC FAILURE
191 $BF P1743 INTERNAL TCM
192 $C0 P1742 INTERNAL TCM
193 $C1 P0562 TRANSMISSION VOLTAGE LOW
194 $C2 P0563 TRANSMISSION VOLTAGE HIGH
196 $C4 P1718 INTERNAL TCM