# Sticky  How To Check Your ECU Error Codes, 87-95 HB pickups



## 88pathoffroad (Jun 6, 2004)

Check here for how:

Ecu Self-diagnostics For 87-95 Pathfinder - Nissan Pathfinder Off-Road Association

Update:

Link above is broken.

Try this... http://www.nissanforums.com/hb-truck/140369-how-check-your-ecu-error-codes-2.html#post1361147

-R


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## Grug (Aug 20, 2009)

So does this procedure take the place of one of those code reader devices you can buy at auto supply stores?


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## 92 GSR-4 (Oct 10, 2009)

Yes, in fact many many vehicles out there can output the codes without a scan tool if you know how to do it. I remember some cars that you can flip the ignition on and off a few times and the "Check Engine Light" (CEL) will blink and you can count the blinks for a code.

In this case, its the same idea, just an LED on the ECU blinks instead of the CEL. Like the other method, you just have to count how many times the red and green LED's blink to get the code.

Also, for future reference, if you ever need to get a CEL code from a vehicle, Autozone and Advance will do it for free.


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## Grug (Aug 20, 2009)

Do you know if the codes changed for '97? The attached write up above says for 1987-1995 (I'm drivin' a '97 HB).


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## jasonm (Nov 30, 2009)

If you have a 96 or newer then you can just use a regular ODB-II reader to read the codes. Auto Zone will do it for free.


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## Grug (Aug 20, 2009)

Auto Zone, eh? Is that a parts supply store or a repair shop chain? Not too familiar with them.


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## jasonm (Nov 30, 2009)

Parts supply store. Most parts stores will read ODB-II codes for free.


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## Wild (Feb 20, 2010)

Thanks for the info! My check engine light just came on today. 

If I counted the blinks correctly I have a code 23 - Idle Switch.

Has anyone dealt with this code before? 

Anyone know where the idle switch is located on a 95' 4cyl 5 speed? 

Is this something to be concerned about?

Thanks


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## provalvemx45 (Jul 29, 2010)

how would u check these codes for an 85? is it the same as the later years??


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## a_cmc_2b (Aug 15, 2010)

Great Info Thanks!


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## hammer1664 (Feb 15, 2007)

Wild said:


> Thanks for the info! My check engine light just came on today.
> 
> If I counted the blinks correctly I have a code 23 - Idle Switch.
> 
> ...


did you ever get a response to where the idle switch is?


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## MaXiLeeCH (Nov 28, 2004)

I am so glad that my 91 Z24 HB does not have an ECU, only a lockup controller for the automatic trans.
Carburettor and ignition points all the way for me!


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## AtomCzar (Dec 28, 2010)

So I have a bench seat...and when I sllid it forward...the box goes with it.  Anyone else have the bench? Did you take the bench out or take the box off?


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## smj999smj (Jan 1, 2006)

Wild said:


> Thanks for the info! My check engine light just came on today.
> 
> If I counted the blinks correctly I have a code 23 - Idle Switch.
> 
> ...


Code 23 wasn't used in 95. Sure it's not code 32? If so, that's for EGR malfunction.


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## TWX (Jan 29, 2010)

I found that the instructions for the V6 were what worked for my '95 I4 king cab.


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## AtomCzar (Dec 28, 2010)

Not sure if anyone else had the same confusion as me. Not sure if I misunderstood the directions or if they are that confusing. I think it's supposed to read like this...

turn the screw fully clockwise-engine light goes out-then it starts flashing to indicate the 5 modes(so it flashes 2,3,4,5,1 and repeats)-turn fully counter clockwise to select the mode after it flashes.

the 5 seconds is a guidline for how long it takes to get to 3 flashes...not how to get to the trouble codes.


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## bilz94 (Jun 7, 2011)

On my '94 King Cab VG30e I _have to remove the seat to see the blinking LEDs. The computer was mounted so that the lights are facing the center console and impossible to see with the seat in place._


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## TWX (Jan 29, 2010)

Yeah. It's clear to me that one group designed the computer, and another group designed the body and wiring, and didn't account for where the diagnostic LEDs or the screw are located. At least pulling the passenger's bucket seat isn't that hard.

Never had to do this with a bench. Hope I never have to.


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## AtomCzar (Dec 28, 2010)

For my bench I just put it all the way back...jam my hand in at a funny angle and lay my head on the floor...


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## 95NissanDriver (Jun 17, 2012)

*95 NB problem*

I ran this diagnostics test on my 95 HB 2.4L 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 stutter. It will stutter for a sec then run fine for a few minutes then stutter 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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## SciFiGuy (Oct 30, 2012)

Your link to the instructions is now broken. Better check it.


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## ctritchie (Nov 14, 2012)

Link no longer nworks


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## TheRepairMan (Jun 30, 2009)

Yeah, the first link in post #1 is broken. (I edited the first post to include a working link.)

See next post for an accurate set of instructions on how to pull codes, plus codes and definitions.

-Roger


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## TheRepairMan (Jun 30, 2009)

All 1996 and newer OBDII, see the footnote at the bottom of this post.

88–94 Nissan Pickup
(1995 was an OBD transition year, so the following may or may not apply.)

ENTERING SELF-DIAGNOSTICS
Using (MIL) Check Engine Light

With passenger 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. My 94 D21 4cyl didn't have a screw holding the plastic cover over the ECU. Yours may be different.

*Turn ignition On.

Turn diagnostic mode selector on ECU fully clockwise (On) and wait until inspection lamps flash. Count up to the number of dual color flashes that indicate the mode you wish to enter, then immediately turn diagnostic mode selector fully counterclockwise (Off).The number of flashes displayed indicates corresponding mode. One flash for mode one, two flashes for mode two, and so on. Three flashes, Mode III, is the (self diagnosis mode) in which you need to enter to read diagnostic codes.* 

In Mode III, begin reading the number of alternating individual flashes each LED displays and take note. Those are your diagnostic codes. They will repeat themselves until all diagnostic codes are displayed. Note, five red and five green flashes (55) means there are no codes stored. All clear.


On all models, when ignition is turned Off during diagnosis, in each mode, and then turned back On again after power to the ECU has dropped off completely, diagnosis will automatically return to Mode I.

For description of modes, proceed as follows:

*Mode I (Mixture ratio feedback control monitor A): during a closed loop condition, the green inspection lamp turns on when lean condition is present and goes off when a rich condition is present. During an open loop condition, the green inspection lamp stays off.

Mode II (Mixture ratio feedback control monitor B): during a closed loop condition, the red inspection lamp turns on and off simultaneously with the green inspection lamp when mixture ratio is controlled within a predetermined value. During an open loop condition, the red inspection lamp stays off. The green inspection lamp function is the same as in Mode I.

Mode III (Self diagnosis): in this mode the DTC is indicated by both the red and greed inspection lamp. The red inspection lamp corresponds to units of 10; the green inspection lamp corresponds to units of one.

Mode IV (Switches on/off diagnosis): during this mode, the inspection lamps monitor switch on/off condition of the throttle valve switch, starter switch and vehicle speed sensor.

Mode V (Real time diagnosis): if a malfunction is present during a driving test, the inspection lamps will display the malfunction condition immediately.*


The early VG30E and 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 has a slotted switch that turns 1/4 or 1/2 turn clockwise and counterclockwise to do the same task. 


Engine specific instructions...

*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. Watch the flashes and count the sequence. In approximately 5 seconds, or immediately when you see three flashes (mode 3) for retrieving the diagnostic codes. Then turn the screw fully counter clockwise. If you missed it, the sequence of flashes 1 through 5 will start again. 
3. The red and green LEDs will then begin to flash the trouble code. (number of red flashes is the 1st digit, number of green 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.

Clearing Trouble Codes

On pre-95 models, MIL stored memory will be erased after selecting Mode III or Mode IV.
On 95–99 models, MIL stored memory will be erased by switching from Mode II to Mode I.
On all models, MIL stored memory will be erased if battery terminal is disconnected.
On 95–97 models, to erase DTCs using Consult, select ERASE in the SELF DIAG RESULTS mode.
On 98–99 models, to erase DTCs using Consult, turn Consult On, select A/T, SELF DIAG RESULTS and ERASE. Select BACK, ENGINE, SELF DIAG RESULTS and ERASE.
On all models, to erase DTCs using generic scan tool (GST), select mode 4.


Trouble Code Chart for 4 cylinder fuel injected KA24E engines.

Codes: 

11 Crankshaft Position Sensor Circuit
12 Mass Air Flow Sensor Circuit
13 Engine Coolant Temperature Sensor Circuit
14 Vehicle Speed Sensor Circuit
21 Ignition Signal Missing in Primary Coil
31 Engine Control Unit (ECU)
32 EGR Function
33 Oxygen Sensor Circuit
41 Air Temperature Sensor Circuit
43 Throttle Position Sensor Circuit
55 No Malfunctions



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. 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.
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.
*



Complete list of other possible OE Codes for all early Nissan models.

*Codes:

11 Crank Angle Sensor/Camshaft Position Sensor
12 Air Flow Meter/Mass Air Flow Sensor
13 Engine Coolant Temperature Sensor
14 Vehicle Speed Sensor
21 Ignition Signal
22 Fuel Pump
23 Idle Switch
24 Throttle Valve Switch
25 Idle Speed Control Valve
28 Cooling Fan Circuit
31 ECU
32 EGR Function
33 Heated Oxygen Sensor
34 Knock Sensor
35 Exhaust Gas Temperature Sensor
36 EGR Control-Back Pressure Transducer
37 Knock Sensor
38 Right hand bank Closed Loop (B2)
41 Intake Air Temperature Sensor
42 Fuel Temperature Sensor
43 Throttle Position Sensor
45 Injector Leak
47 Crankshaft Position Sensor
51 Injector Circuit
53 Oxygen Sensor
54 A/T Control
55 No Malfunction
63 No. 6 Cylinder Misfire
64 No. 5 Cylinder Misfire
65 No. 4 Cylinder Misfire
66 No. 3 Cylinder Misfire
67 No. 2 Cylinder Misfire
68 No. 1 Cylinder Misfire
71 Random Misfire
72 TWC Function right hand bank
73 TWC Function right hand bank
76 Fuel Injection System Function right hand bank
77 Rear Heated Oxygen Sensor Circuit
82 Crankshaft Position Sensor
84 A/T Diagnosis Communication Line
85 VTC Solenoid Valve Circuit
86 Fuel Injection System Function right hand bank
87 Canister Control Solenoid Valve Circuit
91 Front Heated Oxygen Sensor Heater Circuit right hand bank
94 TCC Solenoid Valve
95 Crankshaft Position Sensor
98 Engine Coolant Temperature Sensor
101 Front Heated Oxygen Sensor Heater Circuit right hand bank
103 Park/Neutral Position Switch Circuit
105 EGR and EGR Canister Control Solenoid Valve Circuit
108 Canister Purge Control Valve Circuit*



Note: All 96 and later US market vehicles are OBD II compliant, and codes can be retrieved via the OBD II connector and a compatible, commonly found OBD II scan tool. OBD II codes can be found at OBD-II Check Engine Light Trouble Codes or http://www.troublecodes.net/OBD2/



If there are any points that need to be added or corrected, please feel free to PM me or other moderators. I'll fully amended this post as needed to get this info right.


-Roger


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## TheRepairMan (Jun 30, 2009)

UPDATE courtesy of *jp2code* 

http://www.nissanforums.com/hb-truck/140369-how-check-your-ecu-error-codes.html

===============================

If you are trying to repair the truck based on how it acts, then you are going about it all wrong.

The engines in these trucks are controlled by the ECU. If the ECU detects an issue, it makes the engine act a certain way so the Nissan Repair Center knows where to focus their attention.

What does that mean? That means you need to pull the codes.



























If you do not have a service manual, go here to download one for free.


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