About Trouble Codes

HARD CODE
Any Diagnostic Trouble Code (DTC) that is set whenever the system or component is monitored is a HARD code. This means that the problem is there every time the TCM checks that system or component. Some codes will set immediately at start up and others will require a road test under specific conditions. It must be determined if a code is repeatable (Hard) or intermittent before attempting diagnosis.

ONE TRIP FAILURES
A One Trip Failure, when read from the TCM, is a hard OBDII/EURO III code that has not matured to the full minutes. This DTC can take up to five minutes of problem identification before illuminating the MIL

INTERMITTENT CODE
A diagnostic trouble code that is not there every time the TCM checks the circuit or function is an "intermittent" code. Some intermittent codes, are caused by wiring or connector problems. However intermittent Speed ratio codes are usually caused by intermittent hydraulic seal leakage in the clutch and/or accumulator circuits. Intermittent speed ratio codes can be set by intermittent speed sensor circuitry or by line noise being induced onto one or both of the speed sensor signal circuits. 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.

STARTS SINCE SET COUNTER
The Starts Since Set counter counts the number of times the vehicle has started since the most recent DTC was set. The counter will count up to 255 starts. Note that this counter only applies to the last code set.

When there are no diagnostic trouble codes stored in memory, the DRBIII will display "NO DTC's PRESENT" and the reset counter will show "STARTS SINCE CLEAR" = XXX.

The number of starts helps determine if the diagnostic trouble code is hard or intermittent.
- If the number of starts is less than 3, the code is usually a hard code.
- If the number of starts is greater than 3, it is considered an intermittent code. This means that the engine has been started most of the time 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 as "sufficient vehicle operation such that the coolant temperature has risen by at least 22 °C (40 °F) from engine starting and reaches a minimum temperature of 71 °C ( 160 °F).

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