Postby Empress » March 15th, 2007, 2:25 pm
Overview of accessing the ECM and Malfunction Codes
Accessing the ECM
The ECM is located in the passenger side footwell. You need to remove 2 rivet type fasteners of the right doorstep in order to get the kick panel out. To remove these, unscrew the center part and pull up on the other part. Two metal screws and another rivet type fastener hold the kick panel to the body of the car. Under the panel, is the ECM with its connector. Remove the two screws at the top and bottom of the ECM and gently turn it to get to the Model Selector and RED L.E.D. Don't unplug the ECM to do this! There should be a small sticker by the Mode Selector that tells you to turn it clockwise to set the Modes, and to be sure to return it all the way counter-clockwise to the original position when the car is in use. You will also see the RED L.E.D. inside the ECM.
Diagnostics Modes
There are two modes and two conditions for the engine to be in for running diagnostics. All modes are with the Ignition Switch in the ON position.
* Mode I (Engine OFF)- Bulb Check
* Mode I (Engine ON) - Malfunction Warning
* Mode II (Engine OFF)- Stored Self Diagnostic Results
* Mode II (Engine ON)- Exhaust Gas Sensor Monitor
Note: The ECM will automatically return to Mode I when the ignition is switched OFF. When the ECM is changed from Mode II back to Mode I by using the Mode Selector, the malfunction code(s) stored for Mode II will be erased.
Changing Modes
Switching modes is not possbile while the engine is running.
* Turn the Ignition switch ON
* The ECM is now in Mode I
* To switch to mode II:
o Turn the ECM Mode Selector fully CLOCKWISE, hold for at least 2-seconds and then return the Mode Selector to it's original position. You are now in Mode II.
o (Notes: Return to Mode I by turning the Mode Selector fully CLOCKWISE again, holding for another 2-seconds and turning it back to the original position. Doing this will ERASE any Malfunction Codes that are stored in the ECM for Mode II.)
Reading the Malfunction Codes:
The malfunction modes are indicated by the number of flashes by the RED L.E.D. and the check engine light, you can read either of them, as they both display the same thing. Example: if the red LED flashes once and after a short pause flashes twice, this resembles the number "12".
Please Note: The following chart was derrived from a 240sx service manual. Your car may be different, so please consult your manual for your car.
Code: Item:
11 Cam Position
12 MAF
13 Coolant Temp
14 Vehicle Speed
21 Primary Ingition signal
25 IACV
31 ECM
32 EGR
33 Primary O2 (fron)
34 Knock Sensor
35 EGR Temp
36 EGRC-BPT Valve
37 Closed Loop
41 IAT
43 TPS
65 Misfire, Cyl. 4
66 Misfire, Cyl. 3
67 Misfire, Cyl. 2
68 Misfire, Cyl. 1
71 Misfire, Random
72 Catalyst System
76 Fuel Injection System
77 Secondary O2 (rear)
82 Crank Position
84 A/T Diagnostics Link
95 Crank P/S Cog
98 Coolant Temp
103 A/T Park/Neutral Switch
105 EGRC Solenoid Valve
111 Inhibitor Switch
112 Vehicle Speed Sensor, A/T
113 A/T 1st Gear Signal
114 A/T 2nd Gear Signal
115 A/T 3rd Gear Signal
116 A/T 4th Gear / TCC Signal
118 Shift Solenoid Valve A
121 Shift Solenoid Valve B
123 Overrun Clutch
124 Torque Convertor Clutch
125 Line Pressure Solenoid Valve
126 TPS, A/T
127 Engine Speed Signal
128 A/T Fluid Temp Sensor
How to Check Codes
By: Nick Zluticky
Without OBD II
On 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 malfunction occurs within the ECU/fuel injection system, a diagnostic trouble code may be stored in the ECU and the ‘‘Check Engine’’ lamp will blink. There is also a lamp built into the ECU which will concurrently blink. To read Code output, proceed as follows:
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.
List of Codes
Pre-OBDII
11 Crank Angle Sensor
12 Mass Air Flow Sensor
13 ECT Sensor
14 Vehicle Speed Sensor
16 TCS Signal
21 Ignition Signal Circuit
25 Idle Air Control Valve
22 Fuel Pump Control
31 ECM
32 EGR Function
33 Heated Oxygen Sensor
34 Knock Sensor
35 EGR Temperature Sensor (RH)
41 Intake Air Temperature Sensor
42 Fuel Pump Sensor
43 Throttle Position Sensor
45 Injector Leak
46 Secondary Throttle Sensor
51 Injector Analysis
53 Exhaust Gas Sensor (LH)
54 Signal Circuit From A/T Control Unit To ECM
55 System OK (1990-1995 Q45 only)
65-71 Single Cylinder Or Multiple Cylinder Misfire
72 Three Way catalyst Function
76 Fuel Injection System Function
77 Rear Heated Oxygen Sensor
82 Crankshaft Position Sensor
84 A/T Diagnosis Communication Line
91 Front Heated Oxygen Sensor Heater
103 Park/Neutral Position Switch
105 EGR & Canister Control Solenoid
OBD2 Codes
P0000 No Self Diagnostic Failure Indicated
P0100 MAF Sensor
P0105 Absolute Pressure Sensor
P0110 IAT Sensor
P0115 ECT Sensor
P0120 TP Sensor
P0125 ECT Sensor
P0130 Closed Loop, Bank 1 Or Front O2S, Bank 1
P0131 Front O2 Sensor, Bank 1 Lean Shift Monitoring
P0132 Front O2 Sensor, Bank 1 Rich Shift Monitoring
P0133 Front O2 Sensor, Bank 1 Response Monitoring
P0134 Front O2 Sensor, Bank 1 High Voltage
P0135 Front HO2S Heater, Bank 1
P0136 Rear O2S, Bank 1
P0137 Rear O2S, Bank 1 Minimum Voltage Monitoring
P0138 Rear O2S, Bank 1 Maximum Voltage Monitoring
P0139 Rear O2S, Bank 1 Response Monitoring
P0140 Rear O2S, Bank 1 High Voltage
P0141 Rear H02S Heater, Bank 1
P0150 Closed Loop, Bank 2 Or Front O2S, Bank 2
P0151 Front O2 Sensor, Bank 2 Lean Shift Monitoring
P0152 Front O2 Sensor, Bank 2 Rich Shift Monitoring
P0153 Front O2 Sensor, Bank 2 Response Monitoring
P0154 Front O2 Sensor, Bank 2 High Voltage
P0155 Front HO2S Heater, Bank 2
P0156 Rear H02S Sensor, LH Bank
P0157–P0160 Rear O2S, Bank 2
P0161 Rear H02S Heater, LH Bank Or Bank 2
P0171 Fuel System Lean, Bank 1
P0172 Fuel System Rich, Bank 1
P0174 Fuel System Lean, Bank 2
P0175 Fuel System Rich, Bank 2
P0180 Tank Fuel Temp Sensor
P0300 Random Misfire
P0301–P0308 Misfire, Cylinder No. 1–8
P0325 Knock Sensor, Bank 1
P0330 Knock Sensor, Bank 2
P0335 CKP Sensor (Pos)
P0340 CMP
P0400 EGR System
P0402 EGRC/BPT Valve
P0403 EGR Volume Control Valve Circuit
P0420 TW Catalyst System, Bank 1
P0430 TW Catalyst System, Bank 2
P0440 EVAP Small Leak
P0443 Purge Control/V & S/V
P0446 Vent Control Valve
P0450 EVAP Pressure Sensor
P0500 Vehicle Speed Sensor
P0505 IACV/AAC Valve
P0510 Closed TP Sensor
P0600 A/T Comm Line
P0605 ECM/ECU
P0705 PNP Or Inhibitor Switch
P0710 ATF Temp Sensor
P0720 VSS A/T
P0725 Engine Speed Signal
P0731 A/T 1ST Signal
P0732 A/T 2ND Signal
P0733 A/T 3RD Signal
P0734 A/T 4TH Signal Or TCC
P0740 TCC SV Solenoid
P0744 A/T TCC Signal
P0745 Line Pressure S/V
P0750 Shift Solenoid/V A
P0755 Shift Solenoid/V B
P1105 MAP/BARO Switch SOL/V
P1110 Intake Valve Timing Control, LH Bank
P1120 TP Sensor 2
P1125 Tandem TP Sensor
P1130 Swirl Control Valve Control Solenoid Valve
P1135 Intake Valve Timing Control, LH Bank 2
P1140 Intake Valve Timing Control Position Sensor, RH Bank 1
P1145 Intake Valve Timing Control Position Sensor, LH Bank 2
P1148 Closed Loop, Bank 1
P1165 Swirl Control Valve Control Vacuum Check Switch
P1168 Closed Loop, Bank 2
P1210 Traction Control Signal Circuit
P1220 FPCM
P1320 Ignition Signal, Primary
P1335 CKP Sensor (Ref)
P1336 CKP Sensor (POS) Cog
P1400 EGRC Solenoid/V
P1401 EGR Temp Sensor
P1402 EGR System
P1440 EVAP Small Leak
P1441 VC/V Bypass/V
P1443 Canister Control Vacuum Check Switch
P1444 Purge Volume Control/V
P1445 Purge Volume Control/V
P1446 Vent Control Valve
P1447 EVAP Purge Flow
P1448 Vent Control Valve
P1490 VC/V Bypass/V
P1491 VC Cut/V Bypass/V
P1492 Purge Control/V S/V
P1493 Purge Control/V & S/V
P1605 A/T Diag Comm Line
P1705 TP Sensor A/T
P1706 PNP Switch
P1760 Overrun Clutch S/V
P1900 Cooling Fan
