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Honda CBF125 Service Check Short

Note Date - 20 Jul 2019

By Ren Withnell

Following from a thread regarding diagnostics on the CBF125 I'm putting together this short note.

The Honda CBF125 like most modern machines is computer controlled. While the computer on the basic CBF125 is probably a very simple affair it is just a little more than "totally dumb". It can record a handful of basic diagnostic error codes. For the purpose of assisting with diagnosis wouldn't it be great if it could tell you?

Without a trick screen and without a costly bespoke computer system it still can. All it can do is flash the little FI (engine management) light on the dashboard but that should be enough. 

The EFI or engine management light circled in red
"This is my only way of communicating with you. I am so lonely... ;-("

Firstly you will need a part from Honda. Google part number 070PZ-ZY30100 and you should find a 4 pin block connector with a loop of wire. I *suspect* this part is the same used for several Hondas. This part is called a Service Check Short and as the name implies it shorts out 2 wires. 

A 4 pin plug and a small loop of wire
It ain't anything special.

Once you have your Service Check Short (SCS) you then need to remove the left side fairing trim panel from the CBF125. This will expose a clump of wires which ought to have all the connectors protected by a rubber sleeve. 

Ren's hand is lifting the left fairiing trim panel from the CBF125
Take this bit off.
Inside the fairing is a rubber sleeve in which all the connectors live
Find this rubber protective sleeve.

Pull the sleeve back and find the red connector block that is plugged into nothing. It has a protective cover. Remove the cover - noting that oddly the tang to release the clip pulls outwards not pushes inwards as I'd typically expect. 

The bright red connector is pulled away from the rest of the wiring
This is what we're looking for.
The connector now has the cover off showing the 4 female sockets
And there it is.

With the ignition turned OFF at the key connect the SCS. Turn on the ignition. If there are any error codes stored the FI light with flash long and short. For example 3 short would be 3, 2 long and 1 short would be 21, 3 long and 4 short would be 34. It is possible there is more than one code stored so
  short short short - long long short - long long long short short short short 
would be 3 and 21 and 34.

And that is it - you now know your error codes. 

Wait a minute! When I tried this all that happened is my FI light came on and stayed on. Regrettably Mr Haynes does not explain what this means. I presume, I guess, I am hoping it means there are no fault codes stored and all is well with my aged 125.

Wait a minute!! You want me to spend good money on a plug with a wire? Why should I not just short out the pins myself? Well you could but one of the wires in the block is a live wire(sic). If you accidentally get the wrong pins connected don't come running to me crying because you have fried your ECU computer. Please, don't do that, it'll be very costly and distressing. Use the right tool.

A piece of wire is used to short out 2 pins on the service connector
This is a REALLY REALLY bad idea and could fry your computer.

If you'd like to sponsor Ren a proper Honda diagnostic tool contact

Reader's Comments

Bill said :-
If there are no stored codes the FI light will come on and stay on.

If there are stored fault codes, the FI light will flash.
20/07/2019 11:11:11 UTC
Ren - The Ed¹ said :-
I'm 99.999% sure you're right Bill. There is a tiny possibility things are different for each model of bike though. At present I don't know if there is for example a universal Honda list for fault codes or if each model has it's own list etc etc.
20/07/2019 15:04:43 UTC
Bill said :-
Diagnostic codes are l believe EU legation industry standard, they have a few spare codes non emission related that can be manufacturer specific.Thats how it works for the truck and car industry.
20/07/2019 19:12:13 UTC
Ren - The Ed¹ said :-
I have in my manual the codes for my CBF125, I'll see if they match any other bikes online. Do you work in the motor trade Bill?
21/07/2019 22:37:57 UTC
Bill said :-
I used to Ren but I am now retired, OBD On Board Diagnostics became legislation on cars and trucks,the industry I was in, OBD2 was the standard we used. The diagnostic socket and pins layout are a set standard.As bikes now have to be Euro 4 they will have some form of OBD you my fi d this article interesting
21/07/2019 23:55:13 UTC
Ren - The Ed¹ said :-
Cheers Bill. My plug does not look anything like an OBDii plug but a quick look on Google suggests there are adaptors. There's also a lot of adaptors from the Honda socket to serial which I guess will plug into a computer and allow some kind of program to see what is going on. I tinker with computers for a living and to be honest I'm not that driven yet to tinker with my bike's computer, but it's good to know I can if the need arises.
22/07/2019 07:46:52 UTC
Ian Soady said :-
You can get cheap & cheerful OBD readers that link to a mobile phone / tablet via bluetooth. Effectively the CANBUS data is only carried by a twisted pair of 2 wires so making up an adaptor shouldn't be too hard if you can get a wiring diagram for the bike.

But I could of course be completely wrong.
22/07/2019 10:39:15 UTC
Bob said :-
You may well find that the Honda is not OBDII compliant. Bike manufacturers didn't have to conform to the standard. Cars did but even then you won't get very far on a VW without the VAGCom package.
For my KLX I have the Healtech diagnostic, this plugs in directly to the bike at one end and into a laptop at the other. It enables all sensor values to be read and active tests (fuel pump and fan etc) to be carried out. For under £150 it's a good investment.
When I had BMWs the only option was the £370 GS-911 tool!!
22/07/2019 19:16:09 UTC
Henrik said :-
Bob, been thinking of a VW Caddy, in short what are the options to do most basic diagnose ?

(sorry for of topic, for the Fabia I got a cheap Ebay-tester, but have nor been used yet, so I thought all cars from VAG was possible to DIY simple diagnostics)
23/07/2019 09:49:17 UTC
Ren - The Ed¹ said :-
I've seen the HealTech system for the Honda and this particular one also covers (most) Kawasakis. Due to the bikes Sharon and I own I will invest in one if the need arises.

From my limited knowledge of OBDii and what Bill said I get the idea that the basics are standardised, probably by regulations. It'll be the nitty gritty that will be bespoke to each manufacturer and even each model.
23/07/2019 12:00:54 UTC
Borsuk said :-
Since 2009 I think it was, standard OBD connections and error codes became part of EU regulations. Before that manufacturers used the OBD system as a get rich quick scheme as each model had its own unique shaped port and codes and it was getting expensive for garages to have to carry dozens of these things at a couple of hundred to a few thousand a pop just to do a routine service. Now you can by them for £30. The wifi type are especially useful as you can run apps on your phone that let you have all the dials and gauges that you had to buy the more expensive versions of your car to get. For £60 quid my Suzuki Alto now has a real time rev counter, voltage gauge, coolant gauge and any other gauge I feel the need for. To get those when I bought the car was an extra grand.
Currently these regulations do not apply to Motorbikes and as far as I know that wont be changing in the near future.
23/07/2019 12:48:28 UTC
Bob said :-
I've used a bluetooth OBDII adaptor from Ebay (£7.99) and the Torque app on Android with great success to fix my Suzuki Vitara - it gives access to everything.

Unfortunately many bikes still don't fully conform.
I understand KTMs will allow basic OBDII communications, but active tests and fault codes are not available without the special KTM diagnostic.
I think Triumphs are pretty good, with a full implementation.
BMWs are locked out without the GS-911 tool.

Henrik, sorry I don't know a huge amount about VWs but what I do know is that when I tried my OBDII adaptor on my friends Passat we found that it would connect successfully but we couldn't read or clear fault codes and apparently this VAGCom software is what you need.
24/07/2019 08:41:07 UTC
Upt'North said :-
Someone may have already said this, but if not then Euro 5 starts on 01 01 2020 and a requirement of Euro 5 is OBD 2. I believe it won't be as simple as all bikes will have them from then but then again it never is. We will lose a lot of the current models in this, 2019, production year.
24/07/2019 09:41:43 UTC
Ian Soady said :-
"I've used a bluetooth OBDII adaptor from Ebay (£7.99) and the Torque app on Android with great success to fix my Suzuki Vitara - it gives access to everything."

I have the same but have yet to use it in anger.
24/07/2019 10:47:56 UTC
Hammo said :-
SWMBO has a 2008 BMW F650GS which has always been dealer serviced, now I'm a retired man of leisure I've decided to service my self. To turn off the annoying service indicator I looked at the GS911 and decided I didnt want to spend that much, so I investigated further and landed on the Motoscan android app and an OBDLink LX adapter and cable. So far Ive found this does the job without shelling out mega bucks or being limited on the number of VINs you can use the device on
30/07/2019 09:19:52 UTC
Ren - The Ed¹ said :-
It seems there are a lot of options out there, perhaps too many in some ways. Well done Hammo and thanks for the tip.
30/07/2019 09:37:54 UTC
Eli said :-
Codes 1-3 and 2-8 cold engine starts bad
12/09/2020 08:47:12 UTC
Ren - The Ed¹ said :-
Eli - I've looked in my Haynes manual for the CBF125. I have no entry for 1-3 (13?) or 2-8 (28?).

If the engine starts poorly then runs better when warm that would be oil temperature sensor with a code of 7. Otherwise there are several options that cause the bike to run in "fail-safe" mode.
12/09/2020 10:52:05 UTC

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