Diagnostic Notes

Always begin by reading the diagnostic trouble codes using the DRB scan tool. The test procedure begins with Test 1A - Entering Diagnostic Tests. This test will direct you to the specific test(s) that must be performed. If more than one code exists, diagnostic priority should be given to the active code.

If there is an SCI transmit or receive problem, the DRB displays a no response message. Trouble codes may not be accessible until the problem is corrected.

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.

The 42RE transmission control module may report any of the following diagnostic trouble codes:

11 No Engine Speed Sensor Signal
12 No Output Shaft Sensor Signal
13 No Vehicle Speed Sensor Signal
14 Governor Pressure Sensor Signal
15 Throttle Position Signal
16 Transmission Temperature Sensor
17 Overdrive Off Switch Circuits
18 System Voltage Out Of Limits
19 Standby Voltage Out Of Limits
21 Governor Pressure Solenoid Circuit
22 3-4 Solenoid Circuit
23 Torque Converter Clutch Circuit
24 Overdrive Off Lamp Circuit
25 EEPROM Checksum Error
26 Governor Pressure Sensor Offset Drift
55 End of code transmission.

Diagnostic trouble codes for the 42RE transmission system are not permanent and will change the moment the reason for the code is corrected.

ACTIVE CODE
This means that the problem is there every time the transmission control module checks that circuit/function.

STORED CODE
A stored code is not there every time the control checks the circuit. Most stored codes are caused by wiring or connector problems. Defects that come and go like this are the most difficult to diagnose; they must be looked for under the specific conditions that cause them, Codes will be cleared after 50 key on cycles if code does not reoccur.