For those of you guys waiting, I finally got around today to pulling the codes from the ECU. My car threw a MIL the 2nd time I started it with the G20 ECU, but I don't think you'll get one in a 95-97.

The ECU is from '94 G20 and has been in my '98 SE about 3 months. Codes I got:

7,7: Rear oxygen sensor - "Check the rear oxygen sensor & circuit"

8,4: A/T diagnosis comm line - "Possible dead battery. Harness connectors between the ECM and automatic transaxle damaged."

I was completely expecting the 7,7 code but not the 8,4, but I think this may be because the G20 ECU is from an automatic. I know my battery is not dead and I installed it properly, probably just a side effect or something.

Either way, no matter I have black tape over the light anyways.

The ECU is looking for the automatic computer, that's why it threw a code. The EGR is no surprise though.

How do you retrieve the codes? I want to run a diagnostic on my lady's 98 SE, but I'm not too sure how to go about it. TIA

Originally posted by eric96ser
The ECU is looking for the automatic computer, that's why it threw a code. The EGR is no surprise though.


Ahh..ok that makes sense. Are you still running the G20 ECU?

Originally posted by martin_g34
How do you retrieve the codes? I want to run a diagnostic on my lady's 98 SE, but I'm not too sure how to go about it. TIA

Oh, thats easy. The ECU is in the center of the front of the car, kind of behind the ash tray and under the stereo. You need to remove the plastic panel that covers it and then pull the ECU out to the drivers side of the car. You can twist it to access the screw. Put the car on accesories (but not running), twist the little screw fully clockwise then counter clockwise....shit I forget which is first...www.se-r.net for that. Anyways once you do that the Check Engine light will flash a certain amount of long and short flashes which tells you whats wrong, if there is anything.

Originally posted by Storm88000



Ahh..ok that makes sense. Are you still running the G20 ECU?

My wife's car has it now. I'm using a stock '97 ECU in my car. No codes from this end.

I'm using a stock '97 ECU in my car
Did you ever dyno the different ECU's?

all you have to do is change around a few vacume lines to get rid of the egr stuff. takes about 10 min.

Originally posted by jacen99SE

Did you ever dyno the different ECU's?


I guess you must have missed the thread. Here you go.

http://www.sr20deforum.com/showthread.php?s=&threadid=11848

Originally posted by martin_g34
How do you retrieve the codes? I want to run a diagnostic on my lady's 98 SE, but I'm not too sure how to go about it. TIA

sorry it's so long, but here's the procedure from the SE-R.net FAQ:

ECU Diagnostic Procedure (transcribed from a '95 200SX SE-R Nissan Factory Shop Manual (with some editorial comments).

TOOLS REQUIRED TO ACCESS ECU ON A 200SX SE-R:

Philips screwdriver (to remove screws on cover)
10 mm socket (to remove 2 nuts holding down both the cover and ECU)
Ratcheting socket driver
Short extension
Universal joint

HOW TO SWITCH TEST MODES:

Remove screws and nuts holding cover down. Take care not to drop in to area behind console, 200SX's are known to eat little nuts and screws, etc, in that area (at least mine does...). Remove cover from ECU, the cover is a little tight around the ECU... don't be afraid to pull hard on it, it won't break.
Turn ignition switch to "ON". Do not start engine
Diagnostic Test Mode I - BULB CHECK
Start Engine.
Diagnostic Test Mode I - MALFUNCTION WARNING
Turn diagnostic test mode selector on ECM fully clockwise.
Wait at least 2 seconds
Turn diagnostic test mode selector on ECM fully counter clockwise.
Diagnostic Test Mode II - SELF-DIAGNOSTIC RESULTS
Start Engine
Diagnostic Test Mode II - FRONT HEATED OXYGEN SENSOR MONITOR
Turn diagnostic test mode selector on ECM fully clockwise. (Note, This step erases the DTC/MIL, if not, turn test mode selector fully clockwise and repeat step.)
Wait at least 2 seconds
Turn diagnostic test mode selector on ECM fully counter clockwise.
Return to Step 2.

NOTES...

In Diagnostic Test Mode II - SELF-DIAGNOSTIC RESULTS (Step 6) the ECU will flash the current DTC on the MIL (malfunction indicator lamp). eg MIL 12 (for Mass Air Flow Sensor) flashes long-pause-short-short-pause, and repeats. MIL 43 flashes long-long-long-long-pause-short-short-short-pause, and repeats.
In Diagnostic Test Mode II - FRONT HEATED OXYGEN SENSOR MONITOR, the MIL acts as a primitive Air/Fuel Ratio meter. In closed loop (cruising, light acceleration): ON = LEAN, and OFF = RICH, in open loop (idling, heavy throttle, lift throttle) the light keeps the condition that the light had just before entering open loop.
Switching modes is not possible when the engine is running.
When ignition switch is turned of during diagnosis, power to the ECM will drop after approx. 1 second and the diagnosis will automatically return to Daignostic Test Mode I.
Turn back diagnostic test mode select to the fully counter clockwise position whenever vehicle is in use.

DIAGNOSTIC TROUBLE CODES (DTCS):

CONSULT MIL*1 Items
P0000 55 No self diagnostic failure indicated
P0100 12 Mass Air Flow Sen
P0110 41 Int Air Temp Sen
P0115 13 Coolant Temp Sen
P0120 43 Throttle Posi Sen
P0125 98 Coolant Temp Sen
P0130 37 Closed Loop
P0130 33 Front O2 Sensor
P0135 91 FR O2 Sen Heater
P0136 77 Rear O2 Sensor
P0170 76 Fuel Inj System
P0300 71 Random Misfire
P0301 68 Cyl 1 Misfire
P0302 67 Cyl 2 Misfire
P0303 66 Cyl 3 Misfire
P0304 65 Cyl 4 Misfire
P0325 34 Knock Sensor
P0335 82 Crank Pos Sen (OBD)
P0340 11 Camshaft Posi Sen
P0400 32 EGR System
P0402 36 EGRC-BPT Valve
P0420 72 TW Catalyst System
P0500 14 Vehicle Speed Sen
P0505 25 IACV-AAC Valve
P0605 31 ECM
P0705 103 Park/Neut Posi SW
P1320 21 Ign Signal-Primary
P1336 95 Crank P/S (OBD) Cog
P1400 105 EGRC Solenoid/V
P1401 35 EGR Temp Sensor
P1605 84 A/T Diag Comm Line
P1900 28 Over Heat

Automatic Transmission codes:

CONSULT MIL*1 Items
P0705 111 Inhibitor Switch
P0710 128 Fluid Temp Sensor
P0720 112 Vhcl Speed Sen A/T
P0725 127 Engine Speed Sig
P0731 113 A/T 1st Signal
P0732 114 A/T 2nd Signal
P0733 115 A/T 3rd Signal
P0734 116 A/T 4th Signal
P0740 124 Tor Conv Clutch Sv
P0745 125 Line Pressure S/V
P0750 118 Shift Solenoid/V A
P0755 121 Shift Solenoid/V B
P1705 126 Thrtl Posi Sen A/T
P1760 123 Overrun Clutch S/V

Thank a lot guys.