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  1. #1
    Senior Member
    Join Date
    Jun 2012
    Location
    WA
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    203

    Right Knock Sensor Failed again

    Starting this out because this is the second time this has failed in a couple of months. I'm beginning to wonder if it's something else causing them to fail or if I just installed a defective part.

    Going through the Service Manual, they direct you to look for grounds or shorts in the wiring. Ok. The question I have, if I turn on the ignition and check for voltage at the wiring harness connector, what votage, if any, should I see?

    Anyone know?? There has to be a spec somewhere. I have the factory service manual and I haven't had time to dig around in that too much to figure out if I should or not. The troubleshooting procedure does not cover this.

  2. #2
    Senior Member
    Join Date
    Jun 2012
    Location
    WA
    Posts
    203

    Re: Right Knock Sensor Failed again

    Ok, not that I have had this up long, but it seems that I like to reply to a lot of my own posts

    I swapped the sensors from right to left. I noticed water come out of the protective tubing that covered the wire that goes to the sensor. There was no real way for the water to drain from the tubing. I cut that back to check the wire and noticed noting abnormal. Test Run in the driveway indicates that it is fixed. We'll see...

    If the sensor is bad, it will migrate to the left side and I will know for sure it's not the ECM or wiring. The wire is stiff as anyone would expect of a 10yo Motorcycle. Makes me wonder if the sensor that I swapped out was faulty at all..... :-\

  3. #3
    Senior Member
    Join Date
    Jun 2012
    Location
    WA
    Posts
    203

    Re: Right Knock Sensor Failed again

    Update:

    Looking more like the PGM-FI Unit. Drove the bike to work today and the light came back on with the same fault. I'm not thinking that it's the wiring harness because the resistance readings to the unit from the sensor read 32Kohms and 0VDC with the ignition on, on both sensors to the module. Plan on taking it apart over the weekend to actually troubleshoot the wiring harness to verify it good. Looking at a different vendor to get the part delivered to the island I currently live on. With any luck, I can get some reasonable shipping rates out here from Someone

    The factory replacement unit for 02' is 38770-MCA-751. Some people still sell this part and appears to have been superseeded to 38770-MCA-P00 which should have the effective mapping and run good. Does anyone have any insight on that? I also saw some other modules out there for this but it appears as though the -P00 is the right one.

  4. #4
    Senior Member
    Join Date
    Jun 2012
    Location
    WA
    Posts
    203

    Re: Right Knock Sensor Failed again

    Well, I finally troubleshoot the wiring and PGM-FI Module. The wiring is good, No grounds and I have continuity at <1ohm to the sensors. Took a look at the module PN and it was a -305 which means they actually did swap it out as it was supposed to have been during the recall. Put it all back together, started it up and after about 3 minutes of keeping it running above 2500rpm, the light kicked on and it started to sputter. Likely culprit is the PGM-FI Module. Now I just need to find someone that will ship a -P00 overseas without charging an arm and a leg for shipping

  5. #5
    Senior Member
    Join Date
    Jun 2012
    Location
    WA
    Posts
    203

    Re: Right Knock Sensor Failed again

    So the computer is replaced. I no longer have a check engine light.... I now have a Bone to pick with Honda. Years ago, Noted in Service Bulletin 13, there was a recall done on the bike where it changed the direction that the cooling fans would push air and changed the mapping of the Fuel Injection. I Put the new computer in and it's clearly pushing air the wrong way once up to temp. The part numbers are right for the post recall replacement computer. So, whatever was done to this computer post recall, evidently was not done and they slapped a new sticker on it.

    The part number on the bag is a 38770-MCA-P00 and the part that was in the bag was a 38770-MCA-305. Should the part in the bag have been a -P00 or did they just supersede the number for no random reason?

    Thoughts, Insight?

  6. #6
    Senior Member
    Join Date
    Jun 2012
    Location
    WA
    Posts
    203

    Re: Right Knock Sensor Failed again

    Have done more research into the fans running air out of the front of the Bike. Looking at the Wiring Diagrams, I cannot see how the PGM-FI module can change the direction of the fans because a relay running off of the battery provides (+) voltage to the fan and the (-) comes off of the On/Off Switch. Maybe I'm just being stupid and the only real way to see if this was how it was originally, is to change the module back to the old one to check.

    I'm half tempted to order a Pin-Out box for the PGM-FI Module to have a better feel for what I'm looking at while the engine is running.

    Maybe I just have to re-pin the cooling fan connections to push the air out the sides and not out the front.

    The air is supposed to blow out of the sides and not the front, Right??

  7. #7
    Senior Member
    Join Date
    Jun 2012
    Location
    WA
    Posts
    203

    Re: Right Knock Sensor Failed again

    Well, Apparently no one reads this forum or they think bad things of me

    Anyway.... To follow up, Everything appears to be running fine now that I have changed out the PGM-FI unit. Runs like a Raped ape with no issues.

    For those of you who may read this in the future, that have a similar issue, here are a few lessons learned:

    1. Swap the Knock Sensors from side to side before you spend $100 on a part that you may not need. If the sensor is bad, the fault indications will change.

    2. I didn't find any bad wires, but I highly recommend checking them to make sure you have continuity from the PGM-FI unit to the connector and they are not grounded or open circuited before spending $500+ for a new computer.

    Just my 2Cents

    Have a Fantabulous Navy Day

  8. #8
    Junior Member
    Join Date
    Mar 2018
    Location
    FL
    Posts
    2
    I realize this is an old thread but it came up on the search. I have a left knock sensor code. Please tell me hopefully with pictures how to get to it and what is it I am looking for to change it out. I am going to swamp left to right before anything else. thanks, randy


 

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