GL 1200 ECU compatibility

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Paola Zago
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GL 1200 ECU compatibility

#1

Post by Paola Zago »

Hi all, we have our 1984 GL 1200 with over 360,000km which started to go wrong, it rips, it coughs, every now and then it shoots like gunshots, the local Honda dealership doesn't want to check it because it's too old for them and they have no experience! they say it could be either the ECU or the pickups. I would like to try to start from the ECU, easier to replace, I found on the internet an ECU with a blue label and code 131-100-4261, while mine has a black label and code 131-100-3820, does anyone know if they are compatible? ?
Thank you in advance
Paola
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Whiskerfish
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Re: GL 1200 ECU compatibility

#2

Post by Whiskerfish »

Forgive my ignorance but couple questions?

84 1200 so carburated correct? I did not know Carburated 1200's had an ECU?
"Agreement is not a requirement for Respect" CDR Michael Smith USN (Ret) 2017
"The book is wrong, this whole Conclusion is Fallacious" River Tam
2008 GL1800 IIIA "TH3DOG"
1975/6/7/8/9 Arthur Fulmer Dressed Road bike
1975 Naked Noisy and Nasty in town bike
and a whole garage full of possibilities!!

Psst. oh and by the way CHANGE YOUR BELTS!!!!
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Re: GL 1200 ECU compatibility

#3

Post by redglbx »

Steve, I believe it has only the spark box’s that work with the pickups. Just went through all this on my 78 GL with the 1100 motor, I believe that they are basically allthe same but may require some rewiring, so Paola, that’s where I’d start, there are 2. They are known for what you described.
Red 1976 oe owner
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1980 CBX , in the que, to fix the ignorant heavy handed owner
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1984 GL1200 naked
1969 CL350, in the que
Shadowjack
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Re: GL 1200 ECU compatibility

#4

Post by Shadowjack »

The 1200 ignition box is not an ECU, but a simple spark-amplifier with an integrated vacuum advance function. The 84 box, with the black label, is different from the 85-up box, which has a blue label. I assume this change was made because the pulsers are also electrically different between 84 and 85. My FSM for all years says the pulsers should have a resistance value of about 1200 ohms plus or minus 100, but an 84-only manual says they should be 330 ohms plus or minus 10%. I've measured both types, and they do fit these specs.
Since the later part (blue label) was used for three years, they're easier to find, but whether you can replace the early ignition box with the later one, I do not know.
Paola Zago
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Re: GL 1200 ECU compatibility

#5

Post by Paola Zago »

thanks to all for the replies, honestly I don't understand anything about ohms and similar things, but if I install an ECU with a blue label, what can happen? does the motorcycle work? it works bad? Does the stator burn out? does the regulator jump?
thanks for your patience
Paola
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Re: GL 1200 ECU compatibility

#6

Post by Rednaxs60 »

Paola - I've been researching this issue, like to learn more about these older GWs, mine is the "85 GL1200 FI model. You mention an ECU, think you mean an ignition control module - ICU.

Checked the parts fiche that I use and the 1984 ICU P/N 30400-MG9-004 has been superseded by the 1985 to 1987 P/N 30400-MG9-741. The last three numbers are the manufacturers code, the first 5 are Honda's P/N code. This indicates to me that these units are compatible.

Check the wiring colour coding. Have looked at the wiring in the Electrical Troubleshooting Manual and the Clymer manual, same connector colour code.

The labels you refer to are the manufacturers labels, not the OEM parts numbers. I always use the OEM P/N when comparing. Honda did not manufacture these ICUs, had them made for Honda.

The difference between the two units you mention is where the pulse generator (PG) signal comes from, rear of engine or front of engine.

The engine will start with the "blue" label ICU, if the engine performance is the same as for the replaced unit - the issue lies elsewhere, this unit will not affect the stator or RR - the stator and RR circuit is before the ignition switch.

Good luck.
"When writing the Story of your life, don't let anyone else hold the pen."

Ernest

1985 GL1200 Limited Edition
2014 Can-Am Spyder RT LE
2021 Royal Enfield Himalayan
1995 GL1500 SE CDN Edition (sold)
2012 Suzuki DL1000 VStrom (sold)
Ontario 1985 GL1200 Limited Edition (sold)
2008 GL1800 (sold)
Paola Zago
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Re: GL 1200 ECU compatibility

#7

Post by Paola Zago »

Hi Rednaxs650, thanks for the very technical explanation, I apologize if I hadn't referred to the part list code, but the part list I have, indicates two codes, 30400-MG9-741 and 30400-MG9-742, but for me it is Impossible to know what exact code is installed on my European motorcycle. We tried installing the blue labeled ECU with the manufacturer part number 131100-4261 and the bike started immediately and runs perfectly, I did a short ride, first 7km, then 20km, then about 45km and there seems to be no problem. Our fear is that there may be damage to the electrical system with more intense use, with longer rides. according to your experience and knowledge, what could happen? you wished me luck, so it shouldn't be anything, right?
Somewhere, but I can't remember where, I'm sure I read that they recommended the blue labeled ECU instead of the black labeled one, because it worked better. But I don't know if he meant US models, European models. or if it was good for all versions.
However, I took the black ECU that didn't work well, and the one I got on the internet that didn't work, to a company where they program and service ECUs for Lamborghini, let's see what they can do.
Thanks again for everything.
Paola
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Re: GL 1200 ECU compatibility

#8

Post by Rednaxs60 »

Paola - the ICU has nothing to do with the electrical system, it is ignition control only. The electrical system circuit is separate from the ignition circuit. The new to you ICU will work fine.

The last three numbers of the OEM part number is the manufacturer. the "30400-MG9" is the important part - 30400 is the OEM P/N, the MG9 is the bike designation, the last three as mentioned. Manufacturers put out a contract for a part, companies bid on it, the last three numbers change.

I've started to go to the local Honda car dealership for parts. Honda is good this way, doesn't like to reinvent the wheel.

Cheers
"When writing the Story of your life, don't let anyone else hold the pen."

Ernest

1985 GL1200 Limited Edition
2014 Can-Am Spyder RT LE
2021 Royal Enfield Himalayan
1995 GL1500 SE CDN Edition (sold)
2012 Suzuki DL1000 VStrom (sold)
Ontario 1985 GL1200 Limited Edition (sold)
2008 GL1800 (sold)
Paola Zago
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Re: GL 1200 ECU compatibility

#9

Post by Paola Zago »

Thank you very much Rednaxs650, if I could, I would offer you a fish dinner! one last question from a stupid woman, but if the ECU has, as far as I understand, the function of the ignition, why was the motorcycle malfunctioning when traveling before? it jerked, coughed, and occasionally fired a shot like a pistol, was irregular in acceleration and did not exceed 100 kmh.
Paola (Italy)
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Rednaxs60
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Re: GL 1200 ECU compatibility

#10

Post by Rednaxs60 »

Paola - never heard of a stupid question, heard a lot of stupid answers. Too many questions out there that never get asked, no one wants to be the first.

It's an ICU not an ECU. An answer without a question.

The ICU causes an ignition event based on the engine timing. Engine timing signal to the ICU is based on the pulse generator signal to the ICU. The ICU being made up of electronic components can malfunction today but not tomorrow. Chasing an electronic fault is very difficult especially if it is a random event.

To answer your question in layman's terms, timing was off because the ICU was not processing the PG signal as it should have. Ignition events were not happening at the correct time in order to fire the spark plugs at the correct time, every time.

Thanks for the offer of a dinner, have to take a rain check.

Cheers
"When writing the Story of your life, don't let anyone else hold the pen."

Ernest

1985 GL1200 Limited Edition
2014 Can-Am Spyder RT LE
2021 Royal Enfield Himalayan
1995 GL1500 SE CDN Edition (sold)
2012 Suzuki DL1000 VStrom (sold)
Ontario 1985 GL1200 Limited Edition (sold)
2008 GL1800 (sold)
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Re: GL 1200 ECU compatibility

#11

Post by Whiskerfish »

Just saw one advertised on the old goldwing page of Facebook. https://www.facebook.com/groups/2554489 ... rch/?q=ECU
"Agreement is not a requirement for Respect" CDR Michael Smith USN (Ret) 2017
"The book is wrong, this whole Conclusion is Fallacious" River Tam
2008 GL1800 IIIA "TH3DOG"
1975/6/7/8/9 Arthur Fulmer Dressed Road bike
1975 Naked Noisy and Nasty in town bike
and a whole garage full of possibilities!!

Psst. oh and by the way CHANGE YOUR BELTS!!!!
Paola Zago
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Re: GL 1200 ECU compatibility

#12

Post by Paola Zago »

Rednaxs60 wrote: Tue May 30, 2023 10:07 am Paola - never heard of a stupid question, heard a lot of stupid answers. Too many questions out there that never get asked, no one wants to be the first.

It's an ICU not an ECU. An answer without a question.

The ICU causes an ignition event based on the engine timing. Engine timing signal to the ICU is based on the pulse generator signal to the ICU. The ICU being made up of electronic components can malfunction today but not tomorrow. Chasing an electronic fault is very difficult especially if it is a random event.

To answer your question in layman's terms, timing was off because the ICU was not processing the PG signal as it should have. Ignition events were not happening at the correct time in order to fire the spark plugs at the correct time, every time.

Thanks for the offer of a dinner, have to take a rain check.

Cheers
Thanks Rednaxs650 for all these interesting and useful explanations.
Paola
Paola Zago
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Re: GL 1200 ECU compatibility

#13

Post by Paola Zago »

Whiskerfish wrote: Wed May 31, 2023 8:10 am Just saw one advertised on the old goldwing page of Facebook. https://www.facebook.com/groups/2554489 ... rch/?q=ECU
Thanks for your interest, perhaps it has already been sold because I can't find it. I've seen a couple for sale in Europe as well, but the problem is always the same, do they work? the sellers justify themselves by saying that they prevent from working vehicles! a few years ago I bought one to keep as a spare, and when I recently needed it, I found that it didn't even work, mine worked badly, but this one was dead, and I paid 160 euros for it, plus 23 euros for shipping ! You need to find a serious and trusted seller. in the meantime, I'm waiting for the laboratory that works for the Lamborghini control units to be able to repair mine.
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Re: GL 1200 ECU compatibility

#14

Post by Rednaxs60 »

Paola - The ignition control units (ICU) on the 1200 carb models, and the engine control unit (ECU) on the 1200 fuel injected models are going to be an issue in the years to come. These are great bikes when running well, but if the electronics start to go, oops.

I am doing a computerized fuel injection (CFI) ECU replacement/upgrade project. Replacing the original CFI system ECU with an aftermarket modern ECU - using the Speeduino Project. It's a great learning experience, not too expensive - everything is relative. I've configured this new ECU, installed it and have had the engine running with it installed. A few original systems upgraded to suit.

Going to look at the ICU and determine what it is, know what it does and how. I'm retired and always need something to fill in the time.

Good luck with the laboratory.

Cheers
"When writing the Story of your life, don't let anyone else hold the pen."

Ernest

1985 GL1200 Limited Edition
2014 Can-Am Spyder RT LE
2021 Royal Enfield Himalayan
1995 GL1500 SE CDN Edition (sold)
2012 Suzuki DL1000 VStrom (sold)
Ontario 1985 GL1200 Limited Edition (sold)
2008 GL1800 (sold)
Paola Zago
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Re: GL 1200 ECU compatibility

#15

Post by Paola Zago »

hi, Rednaxs650, you are amazing, your knowledge and availability is fantastic!
Paola (Italy)
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