On many nissan and infinity models, the ecu contronl module computer cna be found under the dashboard on the passenger side kick panel. G20 models, the ECU is located behind the center console. On J30, M30 and Q45 models, the ECU is located behind the RH kick panel.
If a problem occurs in the ECU/fuel injection system, a diagnostic trouble code may be stored in the ECU and the ‘‘Check Engine’’ lamp will blink ro stay solid. Theres also a lamp built into the ECU which will concurrently blink but not on all model, I have a 1996 Nissan 300zx and it doesn't have a led light to indicate this. To get the code, do this:
Turn ignition On, but do not start engine.
Using a small screwdriver, turn diagnostic mode selector switch, located on side of ECU, fully clockwise.
Wait two seconds, then rotate switch to full counterclockwise position.
A malfunction code can be read as the long (0.6 second) blink, indicating the first digit of a two digit number and the short (0.3 second) blink, indicating the second digit.
Ensure that the diagnostic switch is to the full counterclockwise position whenever the vehicle is in use.
w/OBD II
On G20 and I30 models, connect a suitable Scan Tool to the DLC, located under instrument panel fuse box cover.
Clearing Codes
If using a scan tool, follow tool manufacturer’s instructions to clear Codes.
A second, though more time consuming method of clearing codes involves using a small screwdriver to turn the diagnostic mode selector switch, located on the side of the ECM/ECU, fully clockwise. After waiting two seconds, rotate the switch to the full counterclockwise position. The diagnosis will end and memory will then be cleared.
Here is a list of codes to check with:
P0100 - MAF Sensor
P0110 - IAT Sensor
P0115 - ECT Sensor
P0120 - TP Sensor
P0125 - ECT Sensor
P0130 - Front HO2S RH Bank
P0135 - Front HO2S Heater RH Bank
P0136 - Rear HO2S RH Bank
P0141 - Rear HO2S Heater RH Bank
P0150 - Front HO2S LH Bank
P0155 - Front HO2S Heater LH Bank
P0156 - Rear HO2S LH Bank
P0161 - HO2S Heater LH Bank
P0171 - Fuel Injection System Lean RH Bank
P0172 - Fuel Injection System Rich RH Bank
P0174 - Fuel Injection System Lean LH Bank
P0175 - Fuel Injection System Rich LH Bank
P0180 - Fuel Temperature Sensor
P0300 - Multiple Cylinder Misfire
P0301–P0306 - Misfire Cylinders 1–6
P0325 - Knock Sensor
P0335 - CKP Sensor
P0340 - CMP Sensor
P0400 - EGR Function
P0420 - TWC Function
P0430 - TWC Function
P0443 - EVAP Canister Purge Control Solenoid Valve
P0500 - VSS
P0505 - IACV-AAC Valve
P0600 - A/T Control & Communication Line
P0605 - ECM-ECCS Control Module
P0705 - PNP Switch
P1150 - Wastegate Valve Control Solenoid Valve
P1155 - Wastegate Valve Control Solenoid Valve
P1160 - Turbocharger Boost Sensor
P1220 - Fuel Pump Control Module
P1320 - Ignition Signal
P1336 - CKP Sensor
P1400 - EGRC Solenoid Valve
P1401 - Temperature Sensor
P1443 - Canister Control Vacuum Check Switch
P1605 - A/T Diagnosis Communication Line
P1900 - Cooling Fan