(Check Engine) Light 6 Differnt Codes Where To Start?

[4wheeldrivefun]

I have a 1994 nissan pathfinder, Just finished installing a new engine and I seem to be pulling the same codes. I have cleared them and they have returned 3x's.

 

code's

 

45 Injector Leak.

12 Air Flow Meter/Mass Air Flow Sensor, switch it out I have tryed 3 differnet ones

34 Knock Sensor--brand new just replaced it

22 Fuel Pump--Seems to be pumping ok

51 Injector Circuit no idea

23 Idle Switch--no idea??

 

I think this is the cause of my high idle. Anyways no idea where to start. Dose anyone have any idea's

 

[blackspawn]

oh my...

[msavides]

I have a 1994 nissan pathfinder, Just finished installing a new engine and I seem to be pulling the same codes. I have cleared them and they have returned 3x's.

 

code's

 

45 Injector Leak.

12 Air Flow Meter/Mass Air Flow Sensor, switch it out I have tryed 3 differnet ones

34 Knock Sensor--brand new just replaced it

22 Fuel Pump--Seems to be pumping ok

51 Injector Circuit no idea

23 Idle Switch--no idea??

 

I think this is the cause of my high idle. Anyways no idea where to start. Dose anyone have any idea's

 

Man, I would almost want to try another ECU. Perhaps check the wiring to the ECU

[4wheeldrivefun]

crap welp I dont have an extra ecu, I gess i'll just have to buy one. However seeing how i used a 95 engine in my 94 are the 94&95 engine ecu's the same? Also is there a wrightup on how to check ecu engine wiring harness for ohms or something like that to check wiring?

[Terrano1992]

45 Injector Leak.

12 Air Flow Meter/Mass Air Flow Sensor, switch it out I have tryed 3 differnet ones

34 Knock Sensor--brand new just replaced it

22 Fuel Pump--Seems to be pumping ok

51 Injector Circuit no idea

23 Idle Switch--no idea??

 

I think this is the cause of my high idle. Anyways no idea where to start.

Start from repairing fault harness under the hood, from engine to ECU. When all harness problems will be resolved, clear codes, run engine, test-drive and read codes again.

All codes and repair procedures are well described into 1994 FSM, section EF&EC.

1994 Pathfinder ECU can't show Code 22 (fuel pump is not a self-diagnostic item on this model). Me think, this is your mistake with counting LED flashes.

[4wheeldrivefun]

Start from repairing fault harness under the hood, from engine to ECU. When all harness problems will be resolved, clear codes, run engine, test-drive and read codes again.

All codes and repair procedures are well described into 1994 FSM, section EF&EC.

1994 Pathfinder ECU can't show Code 22 (fuel pump is not a self-diagnostic item on this model). Me think, this is your mistake with counting LED flashes.

ink

 

 

hmmm, You say repairing fault harness under the hood? please explane? The harness seems to be fine. The car starts every time. Should i go get another harness from a junkyard car?

[4wheeldrivefun]

anyone have an extra good working ecu for a 1994-1995 Pfinder with an auto tranny if it makes any differance, that they wanta to sell.

 

Whats weird is i have replaced the engine long block and still pull the same codes. From looking at the codes if an new ecu dosnt do it im thinking maybe o2 sensor because they seem to be air/fuel related? If the 02 sensors goes out of these what happends syntoms wise, because everything on the list other than ecu and 02 engine wirin side where replaced.

Edited October 29, 2009 by 4wheeldrivefun

[Terrano1992]

hmmm, You say repairing fault harness under the hood? please explane? The harness seems to be fine. The car starts every time. Should i go get another harness from a junkyard car?

Me think, total harness replacement is a more labor-intensive task than to unbind wire harness, locate short-circuit, wire breakage or other damaged points, repair them and rebind harness with new insulation tape... But it's only my opinion, make your own choice. Harness can look fine at a first glance, but total horror under the covering.

Codes 12, 23, 34 and 51 are caused by bad harness/wiring in most cases. For example, if you have no power at MAF sensor (due to short-circuit or wire break), it will produce code 12 even with a good MAFS. Code 23 (idle switch, buried inside the throttle position sensor) - the same causes. Code 34 means wire break (or shorting) in knock sensor circuit. And code 51 means that injector circuit has too low resistance (injector driver overload, electronic overcurrent protection was activated each time when ECU tries to open a faulty injector).

Code 45 (injector leak) follows code 51, when one or more injectors are open all time (because corresponding control wires has a current leak/short-circuit to the ground). Wiring problems again...

So, your first step - visually check main ECU connector (under front passenger seat) for bad/bend/corroded contacts. Disconnect ground wire from the battery before remove/reattach connector to ECU module.

Next step will require a multimeter (and basic skills to use it for electrical measurements). Measure voltage at corresponding connector pins to find, where is a damage. Locate damaged area and repair it.

 

If you have no FSM, PM your e-mail address to me. I'll send EF&EC chapter to you in electronic form (Adobe PDF format). It describes all diagnostic procedures mentioned above step-by-step, with schematic diagrams and illustrations.

[94extreme]

check all your connections 2x.