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Failing ECM? Opinions?

8K views 23 replies 5 participants last post by  N4SH 
#1 ·
Hey everyone,

New member, long time lurker. I come here for alot of my issues but Ive not run across one like this in the forum so here goes......Apologies in advance if this turns into a long post. I want to give you ALL the info before answers and opinions start rolling in. I recently (about a month or two ago) picked up a 04 R6 from a friend of mine, with about 32k miles on it. Bike has been running great ever since i picked it up and Ive been slowly replacing old parts for new ones. Was planning on taking the bike to get dyno tuned after replacing the old busted slip on for a new shorty coffman. Bike came with a PC3 that wasnt plugged up and Ive never messed with one before so i figured my friend that sold me the bike could help me so it was ready for dyno day. Long story short after plugging the PC3 back up the bike will no longer start and the headlights no longer work. PC3 Plugged up or not the bike will only crank and not actually start.

All fuses and relays have been tested and are all good, those that were bad, replaced.
Fuel pump wont prime unless jumping leads as well as the headlights. (they work when getting a direct 12v)
Cluster works on/off.Turn signal indicators on dash work. ( I don't actually have signals though)
Ignition switch is good
Starter switch is good
Stator tests good
Rectifier tests good
Tip sensor is @0.6 as it should be.
Getting spark

But here's the weird thing. Diag mode is not working for D30-52. Flipping the kill switch does nothing for the diags that call for flipping the switch. I feel that the ECM is just not sending signal to the relays for some reason. I have a used ECM coming in a day or two but wanted opinions on this if anyone has had this happen before. I own a service manual for the bike and have gone over everything twice to make sure they are all getting what the need to work properly. But short of an ECM failure I cant think of anything else that would cause this bike to work one day and not after plugging in a PC3. And yes the bike has a full tank of gas and the bike has oil lol.

There is no codes that come up when turning the bike on but here's what diag mode is saying:
d01: 16-97 when twisting throttle
d02: 92
d03: 0
d05: 63
d06: 63
d07: 0
d08: 0.6
d09: 0.0 (No change when flipping switch)
d20: on (this will stay on as the PO jumped the leads)
d021: on (Jumped leads/always on)
d30-52: (Relay clicks no change on dash)
d60: (Relay clicks and will sometimes crackle if flipping on/off the switch fast)
d61: 30
d62: 1
d70: 0

What do you guys think might be causing my bike to not start?? ECM? User error? Rats? Im curious to know what you guys think!
 
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#3 ·
To be honest Im not 100% sure. Friend I bought the bike from that was helping me plugged in the connector to what im assuming is the injectors after that I personally loosened the negative terminal to connect the ground for the PC3. Thats as much as I did as far as unplugging the battery. I wouldn't put it past that neither of us unplugged the battery (which is the first thing you should do when working on anything that needs electricity to run:rolleyes:).

***After re-reading your question I see you say did we unplug the ECU first. No. ECU stayed connected, PC3 connection was plugged in on the left side under the tank, neg on battery unplugged, ground attached to battery from PC3, then neg terminal was tightened back down. No shorted electronic sounds, no puff of smoke, no fried electrical smell. Just wouldn't start/wont start after all that.
 
#5 ·
I think you may be right good sir. Ill post an update once I get the ecu in either tomorrow or Thursday. Fingers crossed it is in fact a shot ecu as Ive put in alot of work hunting bad wires, fuses, and relays with no results. Thanks for your input ill keep this updated when I learn more!
 
#9 ·
This statement is slightly confusing: "All fuses and relays have been tested and are all good, those that were bad, replaced."
Pertinent information was missed. Which fuses were actually blown? Which relays if any, were damaged?

Looking at the circuit diagram, some of the components you described (ignition coils, injectors, gauge cluster, etc.) are powered via the starting circuit cut-off "relay". It's actually a module of several diodes, resistor and two relays.
374774

In most older automobile designs that I've seen, the computers merely throw ground, or at most provide low-amperage 12v to a relay(s). Wisely, they don't have the ECU directly powering anything but a bank of sensors; and that seems to go along with what I've observed in other vehicle designs. The headlight relay is powered via ignition switch and is signaled via ECU; it throws ground for the headlight relay coil. The ECU has logic that only starts the headlights, once the engine has started... and as you mentioned, it cranks with no start. While switches, relays and connections are sometimes intermittent, solid state electronics usually aren't, unless low on power; capacitors do go bad but are rarely damaged. Make sure your battery is good and "voltage drop test" your connections.

Since you've already ordered the ECU, go ahead and install it. Once you confirm that the issues are persisting, unchanged, go ahead and order that starting circuit cut-off module.
 
#10 ·
This statement is slightly confusing: "All fuses and relays have been tested and are all good, those that were bad, replaced."
Pertinent information was missed. Which fuses were actually blown? Which relays if any, were damaged?
High beam relay was bad, and headlight fuse was bad. The only ones I seemed to need to replace. Sorry I missed that part.

In most older automobile designs that I've seen, the computers merely throw ground, or at most provide low-amperage 12v to a relay(s). Wisely, they don't have the ECU directly powering anything but a bank of sensors; and that seems to go along with what I've observed in other vehicle designs. The headlight relay is powered via ignition switch and is signaled via ECU; it throws ground for the headlight relay coil. The ECU has logic that only starts the headlights, once the engine has started... and as you mentioned, it cranks with no start. While switches, relays and connections are sometimes intermittent, solid state electronics usually aren't, unless low on power; capacitors do go bad but are rarely damaged. Make sure your battery is good and "voltage drop test" your connections.
This is where my issue is with it throwing ground. I honestly don't think it is. Last I checked battery tested at 12.8v. A voltage drop test wasn't done. Ill give that a go and see what I get from that. Thank you!

Since you've already ordered the ECU, go ahead and install it. Once you confirm that the issues are persisting, unchanged, go ahead and order that starting circuit cut-off module.
So you're saying getting another ECU isn't going to fix my issue and that instead its the starting circuit cut-off module?
 
#13 ·
The thread link is to my post concerning the wire taps that the video-article used during installation.

The clicking sound you hear from a relay is a result of the switch contacts closing and electricity arching. Note that the module consists of two relays, and relays with corroded or/and burnt contacts, will still click, but not be able to pass sufficient amperage across the switch contacts. Voltage drop testing is good for finding bad connections in general... whether it's across a wire harness, between batter post and clamp, across two points on a wire, or even across the contacts on a relay. Any more than 8% or 10% of the original voltage at full load, is considered excessive. So if for example, the circuit has the relay loaded to max potential and you read 11v as opposed to the original 12.4v that is on the other side, (meter reads -1.4v) that ~12% drop in voltage voltage would be considered excessive.
 
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#14 ·
Yep. Don't go by sight or sound alone for electrical diagnosis. Only a multi meter can tell you accurately. I had a very complex troubleshootingof my s10 brake lights not working. Bought the factory service manual which is 3 volumes totaling about 8 inches! Anyways after testing wires relays fuses and the switch.. turned out when I pulled the fuse out it didn't look blown. Put it in it made contact for a while. Got the meter out and open circuit. Wiggled and both contacts were powered. Never seen a blade fuse crack like that.
 
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#16 ·
Batteries can die in a few different ways. They can die in a way that allows them to read proper standby voltage, but not be able to pass any load. I don't know that parts stores can load test motorcycle batteris. But memory serving, the battery should be able to maintain ~10.5v during cranking.

Also, it is normal for the pump not to prime. It is also normal for it TO prime. It is circumstantial and I don't know when or why it does vs doesn't. It is one of the items that is powered via the starting circuit cut-off module.

I'm looking at the diagram for my own bike versus yours, but it looks like that they are calling it the starter relay assembly on the parts site.
374811


There are tests you can run to verify that it is the issue. You should have 12v on the SOLID RED wire entering it. This appears to be hot-at-all-times from the injector fuse. The Red/Blue wire leaving it, would be switched on/off with ignition. The relay that controls this switch, receives its 12v signal from the solid light green wire, leaving the ECU. But the ECU may have other logic that determines whether to throw 12v on that wire. Your kill switch drives the coil that activates the switch on the second relay in that module. If you suspect it's bad, voltage-drop test that switch. Use a straight-pin to pierce the Red/White wire entering it, then the Red/Black wire leaving it. (Red/Black goes to the module.) Be careful not pierce yourself in the process. The reading that you get on the meter, is your voltage drop.

But do note, that the engine doesn't crank when that switch is flipped off... at least, not on mine.
 
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#17 ·
Batteries can die in a few different ways. They can die in a way that allows them to read proper standby voltage, but not be able to pass any load. I don't know that parts stores can load test motorcycle batteris. But memory serving, the battery should be able to maintain ~10.5v during cranking.

Also, it is normal for the pump not to prime. It is also normal for it TO prime. It is circumstantial and I don't know when or why it does vs doesn't. It is one of the items that is powered via the starting circuit cut-off module.

I'm looking at the diagram for my own bike versus yours, but it looks like that they are calling it the starter relay assembly on the parts site.
View attachment 374811

There are tests you can run to verify that it is the issue. You should have 12v on the SOLID RED wire entering it. This appears to be hot-at-all-times from the injector fuse. The Red/Blue wire leaving it, would be switched on/off with ignition. The relay that controls this switch, receives its 12v signal from the solid light green wire, leaving the ECU. But the ECU may have other logic that determines whether to throw 12v on that wire. Your kill switch drives the coil that activates the switch on the second relay in that module. If you suspect it's bad, voltage-drop test that switch. Use a straight-pin to pierce the Red/White wire entering it, then the Red/Black wire leaving it. (Red/Black goes to the module.) Be careful not pierce yourself in the process. The reading that you get on the meter, is your voltage drop.
Ill go and test it shortly at least to gain some knowledge, but I may just go ahead and order a replacement while Im sitting here, although I don't think it really is my issue... Im leaning more towards the fuel pump relay now just due to the corrosion on the pins and plug terminals, and the crackling sound it makes when playing with the kill switch but wont know until tomorrow on that one. Ill report back once Ive tested the starter relay. ✌
 
#18 ·
Correction... I think the ECU might be switching ground on that light-green wire, rather than 12v. Either way, it'll be obvious on the volt meter. That module contains the relay that powers the pump, ECU, and injectors. Again, I'm looking at the diagrams for own bike.
 
#20 ·
Bike is back running!
New relay came in but didnt fix the issue. The relay I bought was a dud. New relay when hooked up would cause the bike to stay on even with the key in the off position. took it off, threw some contact cleaner on the old fuel pump relay and the plug that goes to it. turn the key, hit the kill switch and BOOM, pump primes and bike starts up no trouble. Headlights are both working again as well. Crazy what a little corrosion will do to electronics. So one ECU and a fuel pump relay later (neither were needed) and shes running like a champ again! Sadly cant get a refund on the ECU or the relay but at least I have spares should I ever need them. 😅 @Intuit thanks for all your insight, I learned some new stuff about this bike I wouldn't have known and its all really appreciated.

PS. The starter/fuel relay not having good contact was also causing me to not be able to clear codes in diags. Once it was making good connection i was able to clear the single stored code. All is good in the world now ✌

Hopefully this thread will help someone out in the future that runs into this same issue.
 
#21 ·
🏍🎉🎊
I always chock costs like that up to the price of learning. No biggie. Sometimes it's beneficial to hang on to parts, but in the case of the ECU, may as well resell it. May still take a loss but again, just the price of learning.
 
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#22 ·
🏍🎉🎊
I always chock costs like that up to the price of learning. No biggie. Sometimes it's beneficial to hang on to parts, but in the case of the ECU, may as well resell it. May still take a loss but again, just the price of learning.
Yeah, I'm sure I could get my money back for it. Only spent $160 on it. Saw quite a few going for nearly $200 on ebay. But you're right. It was all apart of learning so its no skin off my back. 🤷‍♂️
 
#23 · (Edited)
As far as the fuel prime. My 17 will prime if kill switch off when I turn on key. If kill on (no start) the dash bootup won't prime pump until I hit kill off and starter button.

My luck is as long as I have a spare (electronic or mechanical item) very rarely will I need to put the spare into service. But once I sell or throw the spare.. well then mine breaks.
 
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