Author Topic: Likely ECM failure - anyone got a loaner?  (Read 7146 times)

oztourer

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Likely ECM failure - anyone got a loaner?
« on: August 13, 2012, 04:27:06 PM »
Hi all, I'm looking for a bit of help with my ST1300 electronics. My 2002 ST has been giving error code 25 for some time - left knock sensor malfunction according to the workshop manual, so I wasted a fair bit of time on the left hand sensor and wiring before finding out that the manual doesn't know its left from its right, and the error code actually refers to the right sensor.

To check whether the sensor itself was defective I swapped left and right sensors and I still got error 25, suggesting that the sensor is OK (otherwise I should have got error 26 to indicate that the problem was now on the other side). Next up was to replace the wire from the sensor to the ECM, which had continuity but was frayed. Still getting error 25  :well If my diagnosis is correct that only leaves the ECM.

Before spending big money on a replacement ECM I was wondering if anyone here with a 2002, 2003 or 2004 ST has a spare ECM or would be willing to let me plug their ECM into my bike to confirm the diagnosis? The ECM is located in the tail of the bike and is easily removed without tools, so it shouldn't take long to see if that solves the problem. I am on the Sunshine Coast near Noosa but I am happy to travel within, say, a 120km radius. The part number printed on the label of the ECM is 38770-MCS-G02.

Cheers,
Steve (oztourer)
 

Online Brock

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Re: Likely ECM failure - anyone got a loaner?
« Reply #1 on: August 13, 2012, 05:28:15 PM »
Not having a 1300 to look at, try having a look at the frayed area. You may be able to reinsulate it with some self vulcanising tape. Is the wire a shielded type. or two wire.
Brock
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oztourer

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Re: Likely ECM failure - anyone got a loaner?
« Reply #2 on: August 13, 2012, 05:48:37 PM »
Thanks Brock, I replaced the whole wire. The original is buried in the wiring harness so I couldn't check the condition of much of it. The workshop manual is unclear on the subject but I have read that the wire may be shielded, although the part which I could see was not. My replacement wire is currently unshielded.

I have just read elsewhere that the sensor should probably generate about 1.5V, rising to about 3V if knock is detected, so I plan to measure the current at the ECM end of the wire next. Apparently I can expect an error code if no voltage is supplied to the ECU...
 

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Re: Likely ECM failure - anyone got a loaner?
« Reply #3 on: August 13, 2012, 06:09:31 PM »
Quote
I plan to measure the current at the ECM
   >:()

Pedantic I know, but you will be measuring Voltage, not current (Amps). As an Electrician (Aero type) I cringe when the terms are used incorrectly.

School is now out. :popcorn :popcorn :beer
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oztourer

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Re: Likely ECM failure - anyone got a loaner?
« Reply #4 on: August 13, 2012, 06:15:05 PM »
Oops!
 

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Re: Likely ECM failure - anyone got a loaner?
« Reply #5 on: August 14, 2012, 09:21:46 PM »
Non relevant discussions moved to the tech talk thread in general discusions
Brock
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oztourer

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Re: Likely ECM failure - anyone got a loaner?
« Reply #6 on: August 14, 2012, 09:38:02 PM »
Non relevant discussions moved to the tech talk thread in general discusions

Cheers Brock!
 

oztourer

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Re: Likely ECM failure - anyone got a loaner?
« Reply #7 on: August 17, 2012, 12:29:17 PM »
Here's an update on my investigations into the "error 25" my ECM is giving. Having seen that the wire from the right knock sensor was frayed, I replaced it. I used crimp connectors to thread a new wire from the existing knock sensor connector back to the ECM. I reset the ECM to remove the stored error code. End result: no change, I still got error 25 after holding the revs above 4,000 for about five seconds.

I reset the ECM and spliced a new cable onto the other knock sensor. Again, error 25 on revving the bike. I now had the advantage of crimped connectors on both cables at the ECM so I was able to try a few tests in quick succession: Swapped cables, left sensor disconnected, right sensor disconnected, both sensors disconnected.

This is where I totally lose the plot: I got error 25 in every case! I made sure to reset the ECM between tests, something I am getting quite proficient at after all this practice. When reading out the error code on the dashboard I also gave the warning lamp time to flash out the sequence at least twice in case an error 26 was "queued up" behind the error 25, but all I got was the 25 repeated. At the very least, swapping the cables should have given an error 26.

The workshop manual gives a procedure for checking for ECM failure, which should give 33 blinks, but I cannot get this result so that might suggest that the ECM is OK. Still, at this point I am at a loss and the ECM seems the only likely problem. Can anyone see errors in my logic or tests?
 

Offline rally

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Re: Likely ECM failure - anyone got a loaner?
« Reply #8 on: October 21, 2012, 01:01:20 PM »
 :rd13  I believe a borrowed ECM is linked to the key and will not operate on another bike, we have tried this (see my other entry re the same problem) swapping mine to my mates problem bike. Please let me know if you have solved the problem...RALLY
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oztourer

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Re: Likely ECM failure - anyone got a loaner?
« Reply #9 on: October 21, 2012, 10:14:49 PM »
:rd13  I believe a borrowed ECM is linked to the key and will not operate on another bike, we have tried this (see my other entry re the same problem) swapping mine to my mates problem bike. Please let me know if you have solved the problem...RALLY

All my investigations suggested the problem did lie with the ECM so I eventually bit the bullet and ordered a replacement. It required two new keys as well but luckily it did solve the problem, so the money was well spent and this thread can be closed.
 

Offline winston66

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Re: Likely ECM failure - anyone got a loaner?
« Reply #10 on: October 21, 2012, 11:25:33 PM »
 :rd13 :hatwave :runyay :think1
Winston 66, wonders.
 As I understand it with my simple mind, I wonder if the perstistant (error code) ? problem is actually the knock sensors trying to tell you that there is a problem in the operation of the motor?
For instance , have you done any other mechanical checks on the motor Ie. compression, injector viabiliy, etc and or  an actual check of the iginition timing as these sensors are supposed to detect pre detonation in the cylinders etc and is the fault code alerting you to an actual motor malfunction problem or is it telling you that the sensors and the associated wiring is not doing its job properly.
 I wonder if there is or has been a noticable change in how the motor performes ie. starting, smooth running, power etc.
Have you checked when shortly after starting a cold motor that the individual exhaust pipes are at the same tempreature (I call this a finger test) but be carefull not to burn yourself.
This indicates that the individual cylinders are all firing and operating ok any cylinder that was down on temperature could indicate a potential problem with possibly iginition (spark plug), or fuel (Blocked or damaged injector), or compromised fuel supply (blocked filter).
This might possibly give you somewhere else to go, or to look at.
 Hope that these suggestions are of some use.
Please keep us informed.

Cheers  Winston 66 Northampton
 :dred11 :hatwave :runyay :beer :think1
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Offline alchemist

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Re: Likely ECM failure - anyone got a loaner?
« Reply #11 on: July 09, 2014, 12:56:19 AM »
Oh no  :fp

I've got the dreaded error code 26 when running the engine over 4000rpms and have done a lot of reading across various forums.  It seems as though it's always the ECU being at fault with this one, but I'll rule out my wiring first tomorrow.   Hopefully this will be an easy fix  :crazy
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Offline cravenhaven

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Re: Likely ECM failure - anyone got a loaner?
« Reply #12 on: December 23, 2017, 01:34:08 PM »
I thought it best to stay with this old thread and ask the same question:
Does anyone have an ECU (and key) that I could buy/borrow to rule in/out the ECU problem.

In my case my problems started some months back with an FI code 26 - right knock sensor. I found that the connector housing was melted so eventually got a similar connector off of a honda pilot car and replaced it. Now the problem is consistently code 25 - Left knock sensor, and I have tried everything that I can think of to find the problem (cable conductivity/shorts, voltage measurement, scope on the wires). I even considered Winstons comment about there being an actual problem with the engine but the evidence from web searches indicates its more likely an ECU problem.

My bike is an 02/3 model so the ecu is apparently the same as those up to 07.

Allan
 

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Re: Likely ECM failure - anyone got a loaner?
« Reply #13 on: December 23, 2017, 01:59:01 PM »
Its not the ECU, the Forum in the states is full of knock sensor issues. apparently the fix is to replace the knock sensor wiring back to the ECU.
Brock
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Offline cravenhaven

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Re: Likely ECM failure - anyone got a loaner?
« Reply #14 on: December 23, 2017, 03:55:20 PM »
You might be right Brock, but I have tested the wiring and it appears fine. No shorts, no disconnects. There have been a couple of examples on this forum where ECU replacement has been the solution.
There are as many examples of ECU replacement successes as wiring replacement ones.
 

Offline rally

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Re: Likely ECM failure - anyone got a loaner?
« Reply #15 on: December 25, 2017, 08:43:51 AM »
 :rd13 :rd13 :rd13

Sorry to say but this is a problem with MANY St 1300s , many found that the cable near the knock sensor was burnt through (too close to the exhaust) has been discussed many times on this forum, and this seems to effect the ECU, replacing knock sensors and cables did not work it appears to effect the inside of the ECU, possibly an expensive replacement.  SORRY..
but good luck

Rally
Rally
 
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