About Trouble Codes

ACTIVE (HARD) CODE
Any Diagnostic Trouble Code (DTC) that is set whenever the system or component is monitored is an Active 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 to set the DTC. It must be determined if a code is Active (repeatable) or Stored (Intermittent) before attempting diagnosis.

STORED (INTERMITTENT) CODE
A diagnostic trouble code that is not there every time the TCM checks the circuit or function is a Stored (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. If the DTC is reset (after an ignition cycle) the DTC will be set to Stored (Intermittent) status. A DTC status can be Active or Stored (Intermittent). Active is when the DTC's present in the controller and the transmission is in the particular mode of operation for that DTC. Stored means that the DTC occurred at some point, but is not currently present, or the conditions have not been right to check for the presence of the problem, when a DTC is classified as Stored (Intermittent), no TCM reaction is required.

Emergency function
If DTCs occur, safe driving conditions must be retained but full functionality of the transmission will be limited to avoid damaging the automatic transmission. In the event of certain DTCs the TCM switches to emergency running. The TCM will store the appropriate DTC codes and solenoids will be de energized (turned off)

The transmission effects will be:
^ The last gear shifted remains in that position
^ The modulating pressure and shift pressure increase to maximum value
^ The torque converter clutch is disengaged (turned off

Shifting manually after a DTC detection

NOTE: The vehicle can still be shifted manually to 2nd or reverse gear.

To accomplish these shifts you must
Stop the vehicle
Turn the ignition off
Start the engine
Place the selector lever into D for 2nd gear
Place the selector lever into R for reverse gear

The emergency running function is retained until the DTC is eliminated or the stored DTC code is erased.

Stored (Intermittent) DTCs can be reset by cycling the ignition switch

TROUBLE CODE ERASURE
Diagnostic Trouble Codes can be erased in two ways. The first is to erase the DTC with the DRBIII or scan tool. The second is if the DTC is no longer present, the DTC is reset by the TCM (after an ignition cycle), which will place the DTC in an intermittent status (Stored DTC).

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