ECU Codes and what they mean...G1 & G2

**502 MotorSports** · 02-27-02, 07:35 AM

Some useful info:

Getting that little Check Engine lights on your dash may seem a little discomforting. In reality it is really a miracle of engineering and computer technology. Instead of randomly pocking in vast amounts of wires, sensors, and mechanisms in such complex car as a Legend, this little light tells you that your computer knows exactly what is wrong with the car (most of the time).

That means the exact sensor or gate has been pin-pointed as being either partially disconnected or simply out of acceptable range.

Location of ECU on 1986-1990 Legends

The control unit is located under the passenger seat on sedans and under the passenger foot well carpet on the coupes.
The engine CPU is the form of an aluminum box with a little plexiglass window. All you have to observe is a little red LED.

Location of ECU on 1991-1995 Legends

On the 1991-1995 Acura/Honda Legends, you have to jump a service connector located on the passenger side right under the dashboard near the door. The connector has two pin inputs. Connecting them with something like a paper clip will force the check engine light on the dashboard to display the codes.

Extracting Codes

With the car either running or the key in the ON position, perform the necessary steps above and observe the blinking of the light. The light will blink displaying all the codes in sequence and then repeating them.

Reading Codes

The code numbers are read by counting the number of blinks between longer pauses. On 1986-1990 Legends, the code number is indicacted by a series of rapid LED blinks between longer pauses.

On 1991-1995 cars, codes 1-9 are indicated by a series of short flashes; two digit codes use a number of long flashes for the first digit followed by the number of short flashes for the second digit. So a code 43 will be represented by 4 long and 3 short flashes.

The position of codes in a sequence can be helpful in doing diagnostics. A display showing 1-1-1-pause-9-9-9 indicates two problems occurring at different times. A sequence showing 1-9-1-9-1-9 indicates two problems occurring at the same time.

Resetting ECU

Sometimes it may be useful to reset the ECU memory. Although that maybe done by removing the battery for around 20 minutes or so, this will also kill your clock and radio presets. A more elegant way is to:

on 86-90 Legends remove the alternator fuse for 20 seconds.
on 91-95 Legends remove the ACG fuse in the interior fuse panel for 20 seconds. (note that this will also clear the seat memory)

--------------------------------------------------------------------------------

Below are trouble codes for 86-95 Acura/Honda Legends:

1986-1990 Legend (G1)
Code # Explanation
1 Front Oxygen Sensor
2 Rear Oxygen Sensor
3 Manifold Absolute Pressure Sensor
5 Manifold Absolute Pressure Sensor
4 Crank Angle Sensor
6 Coolant Temperature Sensor
7 Throttle Angle Sensor
8 Top-Dead-Center Position Sensor
9 Number 1 Cylinder Piston Position
10 Intake Temperature Sensor
12 E.G.R. System
13 Atmospheric Pressure Sensor
14 Electronic Idle Control Module
15 Ignition Output Signal
17 Vehicle Speed Sensor
18 Ignition Timing Adjustment

--------------------------------------------------------------------------------

1991-1995 Legend (G2) (Click here for transmission trouble codes)

Code # Explanation
1 Left Oxygen Sensor
2 Right Oxygen Sensor
3 Manifold Absolute Pressure Sensor
5 Manifold Absolute Pressure Sensor
4 Crank Angle Sensor
6 Coolant Temperature Sensor
7 Throttle Angle Sensor
9 Number 1 Cylinder Position (No. 1 Sensor)
10 Intake Temperature Sensor
12 E.G.R. Sensor
13 Atmospheric Pressure Sensor
14 Electronic Idle Control Module
15 Ignition Output Signal
16 Fuel Injector
17 Vehicle Speed Sensor
18 Ignition Timing Adjustment
23 Left Knock Sensor
41 Left Oxygen Sensor Heater
42 Right Oxygen Sensor Heater
43 Left Fuel Supply System
44 Right Fuel Supply System
45 Left Fuel Metering
46 Right Fuel Metering
53 Right Knock Sensor
54 Crank Angle 2 Sensor
59 Number 1 Cylinder Position (No. 2 Sensor)

Dave C ver2.0 · 02-27-02, 07:38 AM

We're gonna sticky this one also.

93typeII · 02-27-02, 09:39 AM

thanks leon now i have a so called "cheat sheet without pulling out the book.

**502 MotorSports** · 02-27-02, 01:47 PM

My pleasure guys

02-27-02, 06:02 PM

Are these codes need for when you get the Stage II chip?? Or Just if you senn the check engine light flashing..

**502 MotorSports** · 02-28-02, 08:40 PM

Quote:

Originally posted by Thai.95LCoupe
Are these codes need for when you get the Stage II chip?? Or Just if you senn the check engine light flashing..

no..these are f you get a check engine light and you retrieve the codes as stated above....G2 is set up differently from G1

FutureX 2001 · 03-09-02, 11:14 PM

Do any of the tranny lights ever flash to give codes too? Just curious... On the AT

***LegendGS*** · 03-09-02, 11:20 PM

I belive that the D4 light flashes for tranny codes.

CakeDaddy · 03-10-02, 08:18 AM

This info is GOLD. Thanks Leon

biggdave15 · 03-14-02, 02:17 PM

thanks much bro on this info heh, now i can find otu exactly why that light is on, it came one yesterday and got me curious, i think i might have blowin a fuel injector, but not really sure, the pcm-fi light is on, and thats the check engine light on 86 acks, well thanks

**502 MotorSports** · 03-15-02, 02:02 AM

Hey guys, I am glad to help. That is what its all about. Good luck with your troubleshooting. If you don't have a Helm's I suggest getting one - http:/www.helminc.com

Rusky · 03-26-02, 06:43 AM

Thanks for the info.

Priceless.:cool:

flashdragoon · 04-07-02, 12:18 AM

very sweet info man, btw how long does the light last?, any way to tell if it's burnt out?

04-27-02, 02:54 AM

What exactly is the benefit of reseting the ECU though? I haven't done it since I did that CAI, should I do it now or would it be pointless?

Trixiem · 04-30-02, 07:02 PM

I have a g2 91 sedan and i don't see an ACG fuse, all i see are ALB fuses thats the closest thing to ACG i can see. Can anyone show me a picture or a chart or something

02-27-02, 07:35 AM	#1 (permalink)
502 MotorSports 502MotorSports.com Join Date: Jan 2002 Location: Louisville, KY Posts: 9,354 Car 1: F.I. e39 540i Car 2: F.I. e46 325xi Car 3: e46 330i iTrader: (0)	ECU Codes and what they mean...G1 & G2 Some useful info: Getting that little Check Engine lights on your dash may seem a little discomforting. In reality it is really a miracle of engineering and computer technology. Instead of randomly pocking in vast amounts of wires, sensors, and mechanisms in such complex car as a Legend, this little light tells you that your computer knows exactly what is wrong with the car (most of the time). That means the exact sensor or gate has been pin-pointed as being either partially disconnected or simply out of acceptable range. Location of ECU on 1986-1990 Legends The control unit is located under the passenger seat on sedans and under the passenger foot well carpet on the coupes. The engine CPU is the form of an aluminum box with a little plexiglass window. All you have to observe is a little red LED. Location of ECU on 1991-1995 Legends On the 1991-1995 Acura/Honda Legends, you have to jump a service connector located on the passenger side right under the dashboard near the door. The connector has two pin inputs. Connecting them with something like a paper clip will force the check engine light on the dashboard to display the codes. Extracting Codes With the car either running or the key in the ON position, perform the necessary steps above and observe the blinking of the light. The light will blink displaying all the codes in sequence and then repeating them. Reading Codes The code numbers are read by counting the number of blinks between longer pauses. On 1986-1990 Legends, the code number is indicacted by a series of rapid LED blinks between longer pauses. On 1991-1995 cars, codes 1-9 are indicated by a series of short flashes; two digit codes use a number of long flashes for the first digit followed by the number of short flashes for the second digit. So a code 43 will be represented by 4 long and 3 short flashes. The position of codes in a sequence can be helpful in doing diagnostics. A display showing 1-1-1-pause-9-9-9 indicates two problems occurring at different times. A sequence showing 1-9-1-9-1-9 indicates two problems occurring at the same time. Resetting ECU Sometimes it may be useful to reset the ECU memory. Although that maybe done by removing the battery for around 20 minutes or so, this will also kill your clock and radio presets. A more elegant way is to: on 86-90 Legends remove the alternator fuse for 20 seconds. on 91-95 Legends remove the ACG fuse in the interior fuse panel for 20 seconds. (note that this will also clear the seat memory) -------------------------------------------------------------------------------- Below are trouble codes for 86-95 Acura/Honda Legends: 1986-1990 Legend (G1) Code # Explanation 1 Front Oxygen Sensor 2 Rear Oxygen Sensor 3 Manifold Absolute Pressure Sensor 5 Manifold Absolute Pressure Sensor 4 Crank Angle Sensor 6 Coolant Temperature Sensor 7 Throttle Angle Sensor 8 Top-Dead-Center Position Sensor 9 Number 1 Cylinder Piston Position 10 Intake Temperature Sensor 12 E.G.R. System 13 Atmospheric Pressure Sensor 14 Electronic Idle Control Module 15 Ignition Output Signal 17 Vehicle Speed Sensor 18 Ignition Timing Adjustment -------------------------------------------------------------------------------- 1991-1995 Legend (G2) (Click here for transmission trouble codes) Code # Explanation 1 Left Oxygen Sensor 2 Right Oxygen Sensor 3 Manifold Absolute Pressure Sensor 5 Manifold Absolute Pressure Sensor 4 Crank Angle Sensor 6 Coolant Temperature Sensor 7 Throttle Angle Sensor 9 Number 1 Cylinder Position (No. 1 Sensor) 10 Intake Temperature Sensor 12 E.G.R. Sensor 13 Atmospheric Pressure Sensor 14 Electronic Idle Control Module 15 Ignition Output Signal 16 Fuel Injector 17 Vehicle Speed Sensor 18 Ignition Timing Adjustment 23 Left Knock Sensor 41 Left Oxygen Sensor Heater 42 Right Oxygen Sensor Heater 43 Left Fuel Supply System 44 Right Fuel Supply System 45 Left Fuel Metering 46 Right Fuel Metering 53 Right Knock Sensor 54 Crank Angle 2 Sensor 59 Number 1 Cylinder Position (No. 2 Sensor) __________________ The Hotness! Elevate Your Standards.... Legend Mod Money! Jasmyn \| 502MS Project e39 \| 502MotorSports MySpace Last edited by LegendGS : 04-05-06 at 12:33 PM.

02-27-02, 07:38 AM	#2 (permalink)
Dave C ver2.0 rh eller Join Date: Jan 2002 Location: Rockville Md Posts: 1,942 Car 1: 92 L sedan and 88 LS sedan (wifes) iTrader: (1)	We're gonna sticky this one also. __________________ Started rebuilding IC engines in 1968 at the US Merchant Marine Academy. Don't think you know more than me about auto/IC/control systems unless you can document your education.

02-27-02, 09:39 AM	#3 (permalink)
93typeII Registered User Join Date: Jan 2002 Location: Mobile, Alabama Posts: 39 iTrader: (0)	thanks leon now i have a so called "cheat sheet without pulling out the book. __________________ cross-drilled rotors Redline synthetic cold air intake full exhaust six-speed

02-27-02, 01:47 PM	#4 (permalink)
502 MotorSports 502MotorSports.com Join Date: Jan 2002 Location: Louisville, KY Posts: 9,354 Car 1: F.I. e39 540i Car 2: F.I. e46 325xi Car 3: e46 330i iTrader: (0)	My pleasure guys __________________ The Hotness! Elevate Your Standards.... Legend Mod Money! Jasmyn \| 502MS Project e39 \| 502MotorSports MySpace

03-09-02, 11:14 PM	#7 (permalink)
FutureX 2001 L E G E N D Join Date: Jan 2002 Location: Montebello, CA Posts: 4,211 Car 1: '95 Coupe Car 2: '94 Sedan GS Car 3: '90 Coupe iTrader: (1)	Do any of the tranny lights ever flash to give codes too? Just curious... On the AT __________________

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02-27-02, 06:02 PM	#5 (permalink)
Posts: n/a	Are these codes need for when you get the Stage II chip?? Or Just if you senn the check engine light flashing..

03-09-02, 11:20 PM	#8 (permalink)
*LegendGS* GS Hog Join Date: Jan 2002 Location: SoCal Posts: 6,849 Car 1: 1994 Legend GS-Auto Car 2: 1994 Legend GS-6 spd Car 3: 1993 NSX-6 spd iTrader: (2)	I belive that the D4 light flashes for tranny codes. __________________ Please read the Forum Rules and other announcements

03-10-02, 08:18 AM	#9 (permalink)
CakeDaddy Banned Join Date: Jan 2002 Location: South West area ABQ,DAL,LasVeg Posts: 2,314 iTrader: (1)	This info is GOLD. Thanks Leon

03-14-02, 02:17 PM	#10 (permalink)
biggdave15 Registered User Join Date: Mar 2002 Location: virginia Posts: 36 iTrader: (0)	thanks much bro on this info heh, now i can find otu exactly why that light is on, it came one yesterday and got me curious, i think i might have blowin a fuel injector, but not really sure, the pcm-fi light is on, and thats the check engine light on 86 acks, well thanks

03-15-02, 02:02 AM	#11 (permalink)
502 MotorSports 502MotorSports.com Join Date: Jan 2002 Location: Louisville, KY Posts: 9,354 Car 1: F.I. e39 540i Car 2: F.I. e46 325xi Car 3: e46 330i iTrader: (0)	Hey guys, I am glad to help. That is what its all about. Good luck with your troubleshooting. If you don't have a Helm's I suggest getting one - http:/www.helminc.com __________________ The Hotness! Elevate Your Standards.... Legend Mod Money! Jasmyn \| 502MS Project e39 \| 502MotorSports MySpace

03-26-02, 06:43 AM	#12 (permalink)
Rusky Registered User Join Date: Mar 2002 Location: Honolulu Posts: 25 iTrader: (0)	Thanks for the info. Priceless.:cool:

04-07-02, 12:18 AM	#13 (permalink)
flashdragoon Re-Member Join Date: Feb 2002 Location: New Mexico Posts: 696 Car 1: 1988 Red Sedan L iTrader: (0)	very sweet info man, btw how long does the light last?, any way to tell if it's burnt out? __________________ 88 Legend Sedan L (dead) 94 Honda accord (daily driver)

04-27-02, 02:54 AM	#14 (permalink)
Posts: n/a	What exactly is the benefit of reseting the ECU though? I haven't done it since I did that CAI, should I do it now or would it be pointless?

04-30-02, 07:02 PM	#15 (permalink)
Trixiem Registered User Join Date: Apr 2002 Posts: 87 iTrader: (0)	I have a g2 91 sedan and i don't see an ACG fuse, all i see are ALB fuses thats the closest thing to ACG i can see. Can anyone show me a picture or a chart or something

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