Computer Issue--- Red Light not appearing ??? - Infamous Nissan

Balkins · 11-27-2021, 07:53 PM

Hey Buds,

My 94, 4cly D21, AUTO is having idle issues and we pulled the seat to check the computer for codes.

Following the Manual instructions for testing idles issues, the computer failed to Flash 'Any Red Lights' as we cycled through the tests.

Not sure what could be the issue...???
Anyone ever have this problem??

Thanks for your input...

.

jp2code · 11-28-2021, 02:43 AM

Sounds like you need another ECU

Balkins · 11-28-2021, 01:53 PM

Quote:

Originally Posted by jp2code

Sounds like you need another ECU

Hi Jp

I was afraid of that. ---->Is it possible to be a Grounding Wire Issue?

SBJ · 11-28-2021, 07:01 PM

I wouldn't rule out the computer just yet. Check the powers and grounds for it first. You'll need a copy of the FSM for the wiring diagrams.

jp2code · 11-28-2021, 07:40 PM

In the 94 Service Manual EC section, the Trouble Diagnoses section on EC-171 shows that the Main Power Supply and Ground Circuit for the KA24E is part of Diagnostic Procedure 22, which is on EC-222.

On EC-179, it shows that the ECM (ECCS Control Module) throws code 31 when it malfunctions.

Writing notes down as I am going through the manual, which is what you should have already done.

On EC-180, it says if you are in Diagnostic Test Mode 2 (Mixture ratio feedback), the Green LED will be ON and the Red LED will be OFF if the engine is stopped while the ignition switch is turned ON. Also, if engine is running and Green LED Blinks and Red LED is OFF, you are more than 5% rich on your fuel mixture ratio. Do any of these match your case? Adjusting the mixture ratio is on EC-166.

The ECM function check is on EC-275.

EC-193 mentions having the pins all connected with no bends or breaks on the terminals.

Page EC-222 starts the Main Power Supply and Ground Circuit procedure. It shows the wiring layout and where your ECCS relay is located (make sure it is good). The following 2 pages go through what to check to make sure you have power, harness continuity, voltage, and ground (ECM terminals 39, 48 and engine ground).

Here is the EC section:

https://www.nicoclub.com/service-man...F1994%2FEC.pdf

Once the page loads up in your browser, you can use the Adobe control to save a copy to your PC.

Balkins · 11-28-2021, 10:00 PM

Quote:

Originally Posted by jp2code

In the 94 Service Manual EC section, the Trouble Diagnoses section on EC-171 shows that the Main Power Supply and Ground Circuit for the KA24E is part of Diagnostic Procedure 22, which is on EC-222.

On EC-179, it shows that the ECM (ECCS Control Module) throws code 31 when it malfunctions.......

Thanks Man...

Yes...we did that testing...but not the ECM test.
What a pain in the Arse !

I'm seriously considering selling this year truck and looking for a OBDII system. I feel sorry for the mechanics and end-users of the OBDI system... its like i'm reading / looking for smoke signals with the flashes, etc.----not to mention the location of it. My Ass and knees are scabbed !

89'HBV6 · 11-28-2021, 10:27 PM

Quote:

Originally Posted by Balkins

not to mention the location of it. My Ass and knees are scabbed !

LOL Remember that the humans that designed these were much smaller than your "average American" human. They could/can fit into much smaller spaces...

jp2code · 11-28-2021, 11:44 PM

Yeah, but you can look at your friends and say, "I don't need no OBD2 code reader! I know how to read smoke signals coming out of my ECM."

I guess that's some comfort. lol

SBJ · 11-29-2021, 02:24 AM

Don't let the magic smoke out of the ECU. If you do that it'll never work again.

The truck runs, right? Don't rule out the possibility that you might just have a dead LED in the ECU. If you can put the ECU in the appropriate diagnostic mode the check engine light should still flash out the codes. The difference is you would just have one flashing LED instead of two as it cycles through the various diagnostic modes.

Whatever you do, don't mess with the idle adjustment screw or any of the other screws on the throttle body. That'll just create a problem where there wasn't one before (ask me how I know). If you find you're having to read error codes frequently you can make a blinky light box thingy to interface with the ancient data link connector under the dash. It's pretty simple to make one, all you need is a momentary pushbutton switch and two 12V LEDs.

Deerhurst · 11-29-2021, 02:49 AM

You just need this if you do:

https://www.sparkfun.com/products/retired/10622

I have talked to folks that have burned out lights on their ECM. Being a 94 you can tap into the check connector and see if that's the case.

11-27-2021, 07:53 PM	#1
Balkins 1994 nissan d21, XE, 2wd Join Date: Apr 2016 Location: florida Posts: 70 Vehicle: 1994 nissan d21, XE, 2wd, automatic Thanks: 89 Thanked 8 Times in 8 Posts	Computer Issue--- Red Light not appearing ??? Hey Buds, My 94, 4cly D21, AUTO is having idle issues and we pulled the seat to check the computer for codes. Following the Manual instructions for testing idles issues, the computer failed to Flash 'Any Red Lights' as we cycled through the tests. Not sure what could be the issue...??? Anyone ever have this problem?? Thanks for your input... .

11-28-2021, 02:43 AM	#2
jp2code Software Developer Join Date: Dec 2011 Location: Longview, TX [USA] Age: 52 Posts: 11,173 Vehicle: 94 LB 2x4 Manual VG33e Thanks: 1,835 Thanked 1,803 Times in 1,573 Posts	Sounds like you need another ECU __________________ Joe (not a mechanic!) • Don't have an account? EMAIL ME Factory Service Manuals: https://www.nicoclub.com/FSM/Hardbody/ Walk-through: Checking Nissan Trouble Codes 1994 VG30E to VG33E with H256 Cams

11-28-2021, 07:40 PM	#5
jp2code Software Developer Join Date: Dec 2011 Location: Longview, TX [USA] Age: 52 Posts: 11,173 Vehicle: 94 LB 2x4 Manual VG33e Thanks: 1,835 Thanked 1,803 Times in 1,573 Posts	In the 94 Service Manual EC section, the Trouble Diagnoses section on EC-171 shows that the Main Power Supply and Ground Circuit for the KA24E is part of Diagnostic Procedure 22, which is on EC-222. On EC-179, it shows that the ECM (ECCS Control Module) throws code 31 when it malfunctions. Writing notes down as I am going through the manual, which is what you should have already done. On EC-180, it says if you are in Diagnostic Test Mode 2 (Mixture ratio feedback), the Green LED will be ON and the Red LED will be OFF if the engine is stopped while the ignition switch is turned ON. Also, if engine is running and Green LED Blinks and Red LED is OFF, you are more than 5% rich on your fuel mixture ratio. Do any of these match your case? Adjusting the mixture ratio is on EC-166. The ECM function check is on EC-275. EC-193 mentions having the pins all connected with no bends or breaks on the terminals. Page EC-222 starts the Main Power Supply and Ground Circuit procedure. It shows the wiring layout and where your ECCS relay is located (make sure it is good). The following 2 pages go through what to check to make sure you have power, harness continuity, voltage, and ground (ECM terminals 39, 48 and engine ground). Here is the EC section: https://www.nicoclub.com/service-man...F1994%2FEC.pdf Once the page loads up in your browser, you can use the Adobe control to save a copy to your PC. __________________ Joe (not a mechanic!) • Don't have an account? EMAIL ME Factory Service Manuals: https://www.nicoclub.com/FSM/Hardbody/ Walk-through: Checking Nissan Trouble Codes 1994 VG30E to VG33E with H256 Cams

11-28-2021, 11:44 PM	#8
jp2code Software Developer Join Date: Dec 2011 Location: Longview, TX [USA] Age: 52 Posts: 11,173 Vehicle: 94 LB 2x4 Manual VG33e Thanks: 1,835 Thanked 1,803 Times in 1,573 Posts	Yeah, but you can look at your friends and say, "I don't need no OBD2 code reader! I know how to read smoke signals coming out of my ECM." I guess that's some comfort. lol __________________ Joe (not a mechanic!) • Don't have an account? EMAIL ME Factory Service Manuals: https://www.nicoclub.com/FSM/Hardbody/ Walk-through: Checking Nissan Trouble Codes 1994 VG30E to VG33E with H256 Cams

11-29-2021, 02:49 AM	#10
Deerhurst 4/86 SE-V6 2 tone 4x4 HB Join Date: Apr 2013 Location: Oregon Posts: 8,070 Vehicle: 1986.5 SE-V6 4WD D21, 2003 Audi A4 Avant 3.0 Quattro Thanks: 919 Thanked 1,093 Times in 986 Posts	You just need this if you do: https://www.sparkfun.com/products/retired/10622 I have talked to folks that have burned out lights on their ECM. Being a 94 you can tap into the check connector and see if that's the case. __________________ 1986.5 SE-V6 4X4 D21 Hardbody Pacesetter Long Tube Headers Morimoto Mini D2S HID Projectors and Hella 500s VG33i

11-28-2021, 07:01 PM	#4
SBJ Total Buzzkill Join Date: Nov 2016 Location: OR Posts: 3,114 Vehicle: '90 D21 4cyl 5spd 2wd Thanks: 347 Thanked 595 Times in 529 Posts	I wouldn't rule out the computer just yet. Check the powers and grounds for it first. You'll need a copy of the FSM for the wiring diagrams.

11-29-2021, 02:24 AM	#9
SBJ Total Buzzkill Join Date: Nov 2016 Location: OR Posts: 3,114 Vehicle: '90 D21 4cyl 5spd 2wd Thanks: 347 Thanked 595 Times in 529 Posts	Don't let the magic smoke out of the ECU. If you do that it'll never work again. The truck runs, right? Don't rule out the possibility that you might just have a dead LED in the ECU. If you can put the ECU in the appropriate diagnostic mode the check engine light should still flash out the codes. The difference is you would just have one flashing LED instead of two as it cycles through the various diagnostic modes. Whatever you do, don't mess with the idle adjustment screw or any of the other screws on the throttle body. That'll just create a problem where there wasn't one before (ask me how I know). If you find you're having to read error codes frequently you can make a blinky light box thingy to interface with the ancient data link connector under the dash. It's pretty simple to make one, all you need is a momentary pushbutton switch and two 12V LEDs.

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