The computer codes are 121155. What does this mean?

Code retrieval can be accessed by the ignition key or by a diagnostic readout box(DRB).To obtain the codes using the key method,set the park brake,and put the vehicle in Park/neutral.

Some 95 and later OBDII vehicles, you may be able to retrieve OBDII codes with this procedure, if equipped with digital dash:

* Turn the ignition key ON,OFF,ON,OFF,and finally ON again(ENGINE NOT RUNNING)
* The codes will start to flash on the POWER LOSS or CHECK ENGINE light.
* FLASH,pause,FLASH,FLASH=code 12

The codes showed are...


Fault Code 12
Description: Memory standby power recently lost
Power loss light: Off
Limp-in mode: None

Possible Causes:* Battery or power line recently disconnected - This code is normal if the electrical system has been worked on or the battery has recently been disconnected. It will be removed after 15 ignition switch on/off cycles.
* Low system voltage, bad battery or battery terminals - If the system recently had a power drop (due to a dead battery or bad alternator), this code will appear. If the battery terminals are bad and the engine was jumped, this code will appear.
* Bad connection or wiring - Check the wiring and connections between the battery, power module, and logic module (or SMEC). Check all fusible links and power connectors to the battery. Clean and regrease any corroded connectors with dielectric grease and repair any shorts.

Diagnostic Method
Trigger Parameters
- Logic module receives power after previously not having power


Results If Component Fails

Fault code 12 is stored. The logic module is basically telling you that it has lost power and will not remember any previously stored codes or engine sensor table data. The code will be removed after 15 ignition on/off cycles and the logic module will use default values for all look-up tables as a starting point until it "learns" the attributes of the engine.


Fault Code 11
Description: Engine not cranked since last reset or no ignition reference signal detected during cranking
Power loss light: Off
Limp-in mode: None

Possible Causes:
* Engine hasn't been cranked since last reset - Power was removed from the logic module (disconnected or dead battery, etc.) and the logic module has no memory of seeing a signal from the ignition reference sensor. Crank the engine and check for the code again. If the logic module saw a signal, the code will be cleared. This code will not show up if the sensor simply fails. The logic module must be reset and the engine cranked to see if the sensor is working.
* Bad connection or wiring - Check the wiring and connections between the hall effect sensor (located underneath the distributer cap) and the logic module. Check the continuity of the two 3 conductor cables coming out of the sensor--these are prone to fatiguing and breaking inside the insulation where they exit the sensor if the cables are not properly tied down. You may be able to resolder them. Clean and regrease any corroded connectors with dielectric grease and repair any shorts. This code will not show up if the sensor simply fails. The logic module must be reset and the engine cranked to see if the sensor is working (see above).
* Hall effect sensor failure- Check the ignition reference sensor and fuel injector sync sensor cables. They are the two, flat 3 conductor cables coming out of the sensor at the base of the distributer cap. These often fatigue where they exit from the sensor. Upon replacing the sensor, make sure the cables are clipped or tied to the distributor cap shroud (or elsewhere) so they do not swing around. This code will not show up if the sensor simply fails. The logic module must be reset and the engine cranked to see if the sensor is working (see above).

Diagnostic Method
Trigger Parameters
- Computer has been reset
- No signal from the ignition reference sensor has been detected

Results If Component Fails
Fault code 11 is stored and the engine will not start (even if the ignition reference sensor is working). A running engine will stall, but no code will be stored. The logic module must be reset and the engine cranked to see if the sensor is working.


Fault Code 55
Description: End of message
Power loss light: Off
Limp-in mode: None

Possible Causes:
* No further fault codes are stored. If this is the only code received, then there are no codes stored in memory. This code will always be given, even if nothing is wrong. If you do not get this code, then you may not be retreiving the codes properly, or the power loss light may be burnt out. The light should come on for 1 second when the ignition is initally turned on as a bulb test.

Diagnostic Method
Trigger Parameters
- No further codes in memory


Hope helps (remember comment and rated this)