NEED HELP WITH 93 PATHY, ACCESS ECU PER SERVICE MANUAL ECU WILL NOT RESPOND WNE TURNED TO DIAGNOSTICES MODE RED LED CONSTANT WITH KEY ON AS WELL AS THE CHECK ENGINE LIGHT, WILL NOT REV PAST 2400 RPMS LOADS UP, STALLS LIKE A MISFIRE, i AM A 18YR DIESEL MECHANIC, THIS IS WHAT HAS BEEN TEST AND VERIFIED
PLUGS/PLUG GAP, OHM PLUG WIRES SPEC, TPS SENSOR GOOD, MAF SENSOR GOOD, O2 SENSOR GOOD, FUEL PUMP PRESSURE SPEC, TEST REGULATOR RISE TO 43 PSI WITH NO VACUUM, CAT CONVERTER NEW, MUFFLER NEW, NOID LIGHTS CHECK GOOD ON HARNESS, FUEL INJECTORS OHM SPEC, PRESSURIZED FUEL SYSTEM PINCHED RETURN/BEFORE PRESSURE gauge NO DROP IN FUEL PRESSURE, CHECKED PULSE CPS GOOD ACTRON SENSOR MODULE TESTOR TIMING VERFIED BY CAMS TIMING MARKS THOUGHT IT MIGHT HAVE JUMPED A TOOTH SPEC. PATHFINDER STARTS AND IDLES JUST WILL NOT ACCELERATE EGR REMOVED CHECKED WITH MITYVAC CLEANED THROTTLE BODY CHECKED VAC LINES, VERIFIED NO INTAKE OR EXHAUST LEAK, SORRY THIS IS SO LONG BUT AS A DIESEL MECHANIC THESE ARE NOT MY SPECIALTY. SEEKING IMPUT IF ANYONE HAS SUGGESTIONS I AM ALL EARS. WONDERING IF THE ALTERNATOR COULD BE BAD NOT SUPPLYING ECU PROPER VOLTAGE AS ECU WILL NOT RESPOND OTHER THAN RED LIGHT BY ITSELF COSTANT ON AS LONG AS KEY IS ON

tHANKS
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problem solved thanks to all bad ecu

Try a different ECU. The Check engine light does not work until 96 on non california models.

What procedure are you using?

1.

Access the ECU, under pass seat normally
2.

Start engine and warm it up.
3.

Turn diagnostic selector in ECU fully clockwise.
4.

After the LEDS have flashed 3 times turn diagnostic selector in ECU fully COUNTER clockwise.
5.

Now read the code from the flashes. 55 is NO codes.

More here:

http://nissannut.com/maintenance/obd

I got problem solved bad ecu