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Ecu Self-diagnostics For 87-95 Pathfinder

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Get check engine light, Check codes get EGR Function? Is this an issue or should I live with it?

Thanks For the Diagnostic Info It is really helpful and well done.

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EGR functionality problems can lead to other issues like idle quality and emissions, along with poor mileage in certain situations. It's meant to work along with the other engine systems, so without it you may experience a few minor problems that may or may not annoy you. ;)

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1992 WD21

Searched and searched. I still don't get it.

I have no check engine light, as others have pointed out.

 

Any more insight??

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On what? How to check the codes with no Check Engine light on the dash? Pull the seat and watch the little blinky liiiiiights.

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Hi, my 1995 Nissan Pathfinder SE has the engine light on. The codes that flash are....2 slow, 3 fast, 4 fast, 5 fast, 1 slow, and both the green and red LEDs are flashing at the same time during the diagnosis process. There are also pauses between each flash, between 2 and 3 it is slight, between 3 and 4 it is longer, between 4 and 5 is is slight, and then there is a pause and then the LED flashes 1 time. I am not sure if I am doing it right, for I am only turning the knob to diagnosis and then the LEDs start flashing. Any help would be most appreciated. Thanks in advance, Michael

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For VG30E with slotted switch: Turn the 'diagnostic mode selector' screw on the ECU fully clockwise. The check engine light will go out. Wait 5 seconds, then turn the screw fully counter clockwise.

 

That should give the codes. Turning the knob one way and not the other way just puts it in Select Mode, I think.

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Do I have a problem with vehicle speed sensor circuit code 14, as I test the sensor? does he have tension electric 5 volts?

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How to pull ECU error codes for 87-95 Pathfinders and hardbody pickups:

 

The ECU is under your passenger's side seat. You can gain access to it by simply sliding the seat all the way forward and removing the plastic cover from the ECU. You can also remove the seat if you want, it makes access a little easier.

 

The VG30i ECU's have a tiny toggle switch on the side of the ECU with a small snap-in switch cover that must be utilized to select the diagnostic mode of the ECU. The 4-cylinder ECU and the VG30E ECU has a slotted switch that turns 1/4 or 1/2 turn clockwise and counterclockwise to do the same task. Some early 4-cyl HB ECU's have the switch as well. In any case it will have one or the other.

 

Pictures: This is the ECU from my very dirty (and wrecked) 89 VG30i Pathfinder. VG30E ECU's have a slotted round switch in the same place as the toggle switch.

 

Seat removed; ECU in place on the floor with cover. The cover has ONE screw holding it down. Remove that and the cover will pull off.

wd21ecu1.jpg

 

Diagnostic selector switch with switch cover removed and set on top of the ECU.

wd21ecu2.jpg

 

This is where the LED lights are visible on top of the ECU.

wd21ecu3.jpg

 

For 4-cylinder:

1. Turn the ignition switch on, but do not start the engine. All of the lights in the dash should be on.

2. Turn the 'diagnostic mode selector' screw on the ECU fully clockwise. The check engine light will go out. Wait 5 seconds, then turn the screw fully counter clockwise.

3. The check engine light will then begin to flash the trouble code. (number of long flashes is the 1st digit, number of short flashes is the 2nd digit)

4. To clear all stored codes and turn the check engine light off, turn the screw fully clockwise while it is in diagnostic mode. Wait 5 seconds, then turn the screw fully counter clockwise.

5. To keep the codes stored, simply turn the key off as the check engine

light is flashing and the ECU will keep all stored codes and the check engine light will remain on.

 

For V6:

1. Turn the ignition switch on, but do not start the engine. All of the lights in the dash should be on.

2. For VG30i: There is a little plastic tab you pull off of the side of the ECU(facing the door). A small toggle switch is behind it with 2 positions, "ON" and "DIAGNOSTICS". Using a small screwdriver or tool, move it to the diagnostics position. The red and green LED's on top of the ECU will blink simultaneously. One time, pause, then 2 times, three times, pause...so on for each mode, 1 through 5. Mode 3 is the most commonly used mode and will yield the ECU trouble codes you need to figure out what's going on with your engine.

For VG30E with slotted switch: Turn the 'diagnostic mode selector' screw on the ECU fully clockwise. The check engine light will go out. Wait 5 seconds, then turn the screw fully counter clockwise.

3. After it blinks both LED's 3 times move the toggle switch back to the on position. After about five seconds it will start to output out the diagnostic codes as with the 4-cylinder ECU. Note each code as it is displayed, the red LED flashing once for 10's, and the green LED flashing once for 1's. Meaning: One red flash and two green flashes means code 12.

4. To clear the ECU of any trouble codes, move the switch to the "DIAGNOSTICS" position then back to the "ON" position and turn off the key.

 

 

 

What is the on position?????? im puzzled or what? toggle switch? i dont have oneeee as far as i know.

 

i have a 95 pathfinder XE

Edited by zelix

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I have done a complete test on my truck and the only problem was translated in code 55. But I found that means no problem. I was shocked to find that especially if that truck was very poor cared during the last 10 years and I think I'm lucky.

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Just wanted to post an interesting tidbit I discovered today.

 

I've got an '89 Pathy with no "Check Engine" light. The gauge cluster has an extra spot for a light right above the "Brake" light. In the name of science I went ahead and installed a bulb in this vacant spot. The light has been turning on with all the other lights when I first turned the key on, but turned off after I started the engine.

 

Today the light came on and stayed on. I went under the seat and read out the ECU codes and noticed that the mystery light on the dash came on every time the red LED on the ECU did. It seems the ECU's red LED and the check engine light are one and the same, and that the only difference between having a check engine light and not having one is installing a light bulb. Maybe a little handiwork with a Sharpie too...

 

Now I just need to hook up a green light and a switch and I can quit digging around under the passenger's seat every time I want to read ECU codes!

Edited by Scottzilla

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Does anyone know the procedure for checking the transmission codes on an 88 Pathfinder V-6 ??? I used to remember , but it has been so long. I remember that there is a sequence of moving the shifter while the ignition is turned on and off , then the Trans power light will flash the codes. Sorry if this has already been posted, I did try searching for the info. Thanks, Scott.

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after reading this I went to see if I could do the self diagnostics on my 94 pathfinder because a check engine light has been on for some time now, and when I got the seat/cover off of the ecu there was no "on/daig." switch but a note that said "for self diagnostics there is a remote box for this see service manual. anyone know anything about this?

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the switch is a dial that you turn with a screw. It deceptively says idle speed next to it and when turned all the way clockwise it enters diagnostics mode.

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hey man love this post.i did it on my 94 xe,shot me a 51.which is injector circuit.the oil smells like gas and i need it to get to work.i was going fine today then it started shaking a running rough again.pparked sat for a while with the engine off,but this only made it worse.even if i gave it full throttle it waS LIKE IT WAS NOT FIRING ON A CYLINDER OR SOMETHING.WHAT THE EFF

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hi yall i just did this diagnostic test.. and thank you for the info i did it to find nothing wrong.... code 55.. no malfunction.. thanks :itsallgood:

Edited by 1990pathy

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code 51 injector curcuit any clues as to what may be a common issue or cause

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code 51 injector curcuit any clues as to what may be a common issue or cause

 

Busted injector or connection? You can try the injector diagnostics in the FSM. One is to systematically unplug injectors while the engine is running to see if ay of them do NOT cause the engine to stumble (if nothing happens when you unplug then the injector wasn't working). The other is the pull the distributor and rotate it by hand (engine off of course) and you should hear each injector click in sequence as you move the distributor around. Oh, and measure the resistances of your injectors. Should be 10-14 ohms I think, but look up the spec for your injectors.

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unplugging seems kinda difficult with the upper plenum in place, and pulling the distributor seems kinda silly since you would need to retime the engine, are there and fsm here to download as i havent seen any yet

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I agree, the unplugging does sound like a pain. Retiming the engine takes like 2 minutes though, not to mention that if you mark the distributor well you don't even really need to do it. Yes, FSM is linked up here somewhere, shouldn't be hard to find... :)

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I ran this diagnostics test on my 95 HB 2.4L ( I know its not a pathy but its still a Nissan right? LOL) and the code I come up with was crazy. This is how it went 1 long blink, then 2 long blinks, then 3 short blinks, then 4 short blinks, then 5 short blinks. each number of blinks were divided by a short pause. and all were the red led. can anyone please tell me what code this is.

 

The problem Im having with the motor is ( I hope I can explain this good enough to understand) While taking off when the rpms get to about 3300 it starts jumping as if it hit the rev limiter. once the rpms are above that point it straightens out and runs fine. Its alot worse when the motor is cold. The other problem is while driving down the road in 5th gear and holding speed it will start to studder. It will studder for a sec then run fine for a few minutes then studder for a sec then run fine for a few minutes.

 

Anyone have any clue what could be my problem and how to fix it. Thanks in advance for any advice

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95 Nissian Driver:

Read the instructions again. The 1,2,3,4,5 blinks you are seeing are mode selection blinks. As soon as you see 3 blinks then turn the screw the other direction to enter mode 3 which is the stored code reading mode, THEN start reading the number of blinks (red then green) to determine the stored code number(s).

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i just diagnosed my 93 pathfinder and it blinked both once,long pause blinked both twice,pause,blinked both three times,pause,blinked both four times,pause,and blinked both five times,can anyone figure that out?

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