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Featured How to add new key to Honda CB400SF ABS

Discussion in 'Maintenance and Servicing' started by evman, Apr 17, 2015.

  1. When I bought my CB400 I only got one key, which due to the HISS immobiliser, can be a very expensive issue if lost, as without an original key the only way to get a new one is to replace the entire ECU. So I thought best to make a spare ASAP. You can take it to a dealer, but I like doing things myself. I thought I'd write up how it's done for the CB400SF ABS, from 2008 on, as it seems to be slightly different than with other Honda HISS bikes, the non ABS version may or may not be the same. You can have up to 4 keys added.

    Warning: This is how it done by the dealer, so it should be relatively safe, but ff you try this and fry your bike, don't blame me. Make sure your wires,clips and plugs are well insulated and soldered.

    You need to build a "special" cable to enable the ECU's key programming mode. Honda sell one for $$, it is just two cables.

    Things you will need:
    • A new, blank Honda HISS transponder key that has been cut to match your new key by your local key cutter (CBR 600RR 954 1100RR 600RR 954RR 1000RR CB400 VT750 seem to be the same). These can be bought off eBay (~$20) or from the dealer (probably more expensive). Note it MUST have a blank honda coded transponder chip in it, some keys don't. A chip from an old bike may not work.
    • Two wires ~40cm long, preferably different colours.
    • Two small alligator clips
    • A JST Japanese Sumitomo 2 way Connector (Female), again can be bought off eBay (~$3)
    • Soldering iron.
    • A working key that will start the bike.
    • Any other keys you already have for bike as all keys get erased so need to be readded.

    First you need to find the plug for the crank pulse sensor, you can find it by tracing the wire from the sensor, which is located on the left site of the engine.

    Mine was in a stupid place under the tank between the airbox and battery. I had to remove the fuel tank, then move the ECU out of the way (it just slides up).
    Its a red plug, which required a lot of fiddling and dexterity to get out and unplug. I decided to move mine to to the left side of the bike, where I think it's probably meant to be for easier access so I didn't need to remove the tank. Your's may be here already.
    Note that there are two wires coming out of the plug that leads to the ECU, a yellow (positive) and a white (negative).

    Next you need to build the cable, which is nothing more than a plug that goes to two alligator clips. Solder one end of each wire onto the metal connectors and the other ends to the alligator clips.
    Make sure the wire you want to be negative matches up the white wire on the bikes plug, and the positive wire to the yellow wire. Triple check this. You can add a inline fuse to the wires for extra safety if you like. I like to live on the edge.

    Once you are happy with your plug, unplug the crank pulse sensor and plug your new cable into the crank pulse sensor plug that leads to the ECU, the plug lead to sensor is left unplugged.

    Access the bikes battery and using the alligator clips attach the negative wire to the negative battery terminal and the positive to the positive terminal. triple check this. Make sure nothing is going to short out and fry things.

    Make sure the engine cutoff switch is in the run position and that the new key is a few meters away from the bike.

    Now you need to go through the programming sequence.
    1. Insert your working original key into the ignition and turn to on. The HISS light on the instrument panel should remain on and not flash. If it flashes, there is error (it flashes a code apparently).
    2. Unclip the positive alligator clip from the battery terminal and touch it to the negative terminal of the battery for at least 2 seconds (this is the bit that is different for the CB400SF ABS, other Hondas you seem to just unclip the positive for 2-5 seconds then clip it back on, took me awhile to find this info).
    3. reclip the positive wire to the positive terminal.
    4. The HISS light should go off then repeatedly flash 4 times every few seconds - you have successfully enabled key programming mode and the original key is again registered.
    5. Leave the wires connected, turn the ignition off, remove the key and place it few meters away.
    6. Get the new key, place it in the ignition and turn in to on.
    7. The HISS light should go off then repeatedly flash 4 times every few seconds - you have successfully registered the new key.
    8. repeat for steps 5 to 7 for any remaining keys (max 4 keys).
    9. Turn off ignition, disconnect wires a plug back in crank pulse sensor. Put bike back together if the fuel tank is off.

    All your keys should now start the bike :)
    • Informative Informative x 6
  2. Whilst your homebrew engineering efforts are to be applauded and your desire to assist others within the Honda community is without reproach. Imagine if you will:

    You park your bike somewhere public and along comes Mr Thief, he lifts your bike onto a low-loader/ute/transit and sneaks away. Easily done right?

    Now, he reads your post, this post. Armed with it's content he buys a used ignition lock + key set for a Honda CB400 from eBay.

    Does he now have the ability to install a working ignition and key setup then reprogram it to the bike’s HISS? If so, he’s just got himself a legit bike-key-immobiliser combo in a very unpleasant fashion….
  3. #3 evman, Apr 17, 2015
    Last edited: Apr 17, 2015
    No because he needs the original key, which if he had would have meant he'd already rode your bike away ;)

    The point is, if you don't have a key for your bike (i.e lose it), you can never start your bike again without replacing the ECU etc. Not even Honda can get you a new key.
    • Informative Informative x 1
  4. #4 yardman, Apr 17, 2015
    Last edited: Apr 17, 2015
    Cool, so essentially the "computer says no" to reprogramming HISS if the immobiliser is not already deactivated by the original key beforehand - all good then.

    Not sure how you figured this out but good work!
  5. Thanks heaps mate I'll do mine this weekend!
  6. Good job working it out! ;)

    You should hire out your cable for a 6-pack :)
    • Dislike Dislike x 1
  7. Happy for people to borrow it, but my electrical engineering skills are not the best, so I'm not sure how long the cable will last, it was designed to be used once :)
  8. will this work for cb400sf spec 3?
  9. Yes, but the plug is in a different spot, might be a different plug type and you don't need to touch the positive cable to the negative terminal, you just unclip it for 5 seconds. You can get a PDF of the spec 3 service manual on the internet which shows where the plug is and how to do it. The cable seems to be the same for all Hondas just with the appropriate plug, although some people of put a 100ohm resistor on the positive lead. Do some googling to see the other Honda bikes being done.
  10. thank for the reply,,still no luck doing it,,spec 3 service manual not sayin anythin where to find that wire,
  11. Just trace the wire from the crank pulse sensor
  12. did it,,tried many times using my own made wire tool,,i think should buy honda hiss tool,,
  13. HISS system is pretty damn simple when you have a key, apply 12v to positive(signal) side of CPS, cycle keys, job done. It's a variant of the old Honda red key system from the late 90s cars. Issues occur when your battery is not quite 12v(this can include a bad ground), or you have multiple transponders within detection radius(approx 10cm). However you'll never brick the bike as you're adding keys to ECU memory, never removing them. If you wish to delete keys from ECU memory you need a new ECU or someone who knows Honda immobiliser systems inside and out such as a qualified locksmith, the same applies if you have lost all available keys. I've done probably 30+ HISS bikes, takes a fair bit of time with removing and cutting open ECU etc but it's possible.
  14. When I first read this post I was concerned about theft potential, this weekend I learnt the true thieves are the dealerships - £115 + GST to code a key, plus $44 for the key and whatever it costs to have it cut!

    So, using this post as a reference, I found a bit more info online, my 2014 CBR500 now has an extra key, cost me about $7 in electronic components and probably an hours all up.

    Great work OP, apologies for my initial scepticism.
    • Like Like x 1
  15. Ok .. just did 2 spare keys for my CB400SF (purchased S/H with only one key) total cost $68 for 2 new key blanks from a Honda dealer, another $15 to get them cut, the wire 'n stuff I had laying around .... job done successfully thanks to the good info from 'evman' .. and they (the keys) all work perfectly ...

    • Like Like x 1

  16. Sir Evman, i just want to clarify that the positive cable don't need not touch the negative terminal because I already done that that procedure but to no effect. I actually temted to try your procedure but i am worried that I might fry my CDI. My bike is a CB400SF Spec 2.
  17. I'm not sure what the procedure is for the spec 2, the 5 sec disconnect info was from the spec 3 service manual. I thought you had already reprogrammed your keys successfully though?
  18. Thanks sir Evman for the reply, but I think you have mistaken me to someone. Anyway, i'll try to the procedure again 'till I get it. Thank you!
  19. #19 Joe007, Feb 14, 2016
    Last edited by a moderator: Feb 15, 2016
    Hi, very informative thank you very much for the write up its saves me a lots of $! I'm just about to do this on my 2012 cb400 ABS. Do I have to put in that 100 ohm resistor or not for my model? I'll get my key which was ordered from ebay and will update how it went just not sure about this resistor yet.

    Hey yardman what have you done differently then listed in this post? I have cb400 ABS 2012. What extra info did you find? Just want to get it right without frying the ECU... Thanks
  20. Joe007Joe007 Some do it without the resistor - your ecu, your gamble. You can get the from Jaycar electronics, a couple of bucks for a two pack. The process is the same for all HISS models. Look on youtube there's a guy that takes you through doing a cbr500r, so it's a recent vid - it'll be basically the same as that.

    Edit: also if you cant get the sumitomo connectors use the 2.5 mm (I think, the smallest ones you can get) single female spade connectors. Make sure you use heat shrink so they dont make contact with each other,