SL L4-1.9L SOHC VIN 9 (1991)
Shift Indicator: Testing and Inspection
NOTE: The function of the "SHIFT TO D2" lamp used from 1991 to 1992 was replaced by the "HOT" lamp in 1993.
DESCRIPTION
The powertrain control module, used on vehicles equipped with automatic transaxles, contains an engine control module (EC) and a transaxle control
module (TC). These control modules communicate internally over a serial peripheral interface (SPI) bus. When the transaxle control module (TC)
detects a malfunction in the automatic transaxle, a code is stored in the transmission control module's memory and an indication is sent to the engine
control module to turn on the SERVICE ENGINE SOON telltale. If the ALDL is grounded, the transaxle codes flash on the SHIFT TO D2 telltale
lamp located in the instrument cluster.
READING CODES
Following the output of code 12 during diagnostics, the SERVICE ENGINE SOON telltale lamp will indicate a diagnostic trouble code three times if
a code is present, or it will simply continue to output code 12. If more than one diagnostic trouble code has been stored in the PCM's memory, the
codes will be displayed from the lowest to the highest, with the exception of code 11 which indicates transaxle codes. Code 11 will always flash last
followed by the SHIFT TO D2 telltale lamp which will flash transaxle codes. Each code will be displayed three times.
ADDITIONAL LAMP LIGHTING
The SHIFT TO D2 indicator lamp is also illuminated when any of the following conditions exist:
^
For 1991 vehicles, any time serial communications to TCM are being run.
^
The engine running and the system is failed at low line.
^
The engine is running and all gears above 1st (2nd, 3rd and 4th) are lost in Drive.
^
The engine is running and the master enable relay is turned off for any reason other than hot conditions and the vehicle speed is less than 25 km/h
(15 mph). These include:
- High ignition voltage.
- Low ignition voltage.
- Master relay failed open.
- Master relay shorted across coil.
- Serial communications failure.
^
The engine is running and 3rd or 4th gears are stuck on and the vehicle speed is less than 25 Km/h (15 mph).
^
The engine is running and TCC is stuck on and first gear is unattainable with turbine speed less than 700 rpm.
^
The ECM will light the SHIFT TO D2 light when it loses communications with the TCM (ECM Code 82).
NOTICE: When the lamp is illuminated because of multiple failures, only one code has to be set, the other conditions only need to be present
(have not met all the parameters to cause the code to set).
