Anybody know if there is a way to test an ECU. My '01 450ES won't shift.

I have gone through all the tests in my manual and it has isolated the problem as faulty electronic control unit. I would like to test it before I spend a few hundred to try a new one!!!! They say these things (ecu's) are bulletproof, so I'm a little leary thats the problem.

 

2 things it could be that asre common for the 450. A speed sensor or the shift control motor is bad. I have never had to replace a faulty ECM on a 450.

If it shifts good, put the unit in 3rd gear and ride it until it hits the rev limiter a few times. If it quits shifting then, the Speed sensor is bad

If it just will not shift at all, the shift control motor may need replacement. Take it apart and inspect the armetures comutator and brushes. If the Ecm 'sees' Low or high resistance from the shift control motor it will shut down the electric shift system and all tests you do will lead to ECM replacement, although the ECM is only doing its job and nothing is wrong with it

----- Gimpster -----

 

FYI... on ebay right now, there is a ecm for 50 bucks. But I agree with gimpster, its rare that the ecm is bad.

 

Thanks for the info.
I can shift it manually with the handle and spindle and drive it, but the elctronic shift is dead. Readout shows "--" in 2,3,4th. The control motor turns when I put power to it?? I dont have my manual in front of me but I think we checked the speed sensor.
I put it through the ice while running and it was submerged for an extended time, if that gives you any clues. I got her runnin fine and have power, lights, etc, now but no shift????
Appreciate any advice!!!

 

I'll go check that out, thanks!!!!
I'm also suspicious that it is the ecu. Thats why I was looking for a way to test it before I grab a new one!! My local dealer is useless, he says they can't test it unless they have the whole machine there and they whack you $100 when you walk in the door.

 

My personel quad is a 2001 450 foreman. When I bought it my display did the same thing and I chased the problem over and over. I had tested my shift control motor with 12 volts also and it spun fine. I believe these motors operate on 5 to 7 volts. I also threw an ECm at it and it did not cure the problem. Gear position switch also Cluby on here kept telling me it was the shift control motor and I would not believe him because I could get it to spin off of 12 volts both ways. The test in the servive manual is only to see if power is going to the speed sensor and a slight voltage rise when the wheels are turned. The only way to tell if it is working is to watch for any glitch in the MPH display. Honda's test will not pick up a high end glitch in a speed sensor A lot of times it takes hitting the rev limiter to set it off as being bad. This system has no way to get codes as it is pre 2002. It will only shut down the system is a problem is noted. What convinced me is when I pulled the shift control motor apart, cleaned it and reinstalled. My display began to read all the gear positions, for about 15 minutes of riding then went into shutdown again. I ordered a new shift motor, installed it and have not looked back since. Display and shifting work and read like they are supposed to.
Here is a good one to compare. WHen you look for a voltage draw on a car, bike, etc... you disconnect the negative battery cable, clip one end of a test light to the unhooked battery cable and the test light probr to the negative terminal. If you have a draw (even the slightest) the bulb will glow. You cannot test for a draw across the posative and negetive terminals of the battery and get these results.
Everyone on here says to check a shift control motor by connecting a positive and negative cable to it and check if it turns in each direction. I think of this as a quick test, but you get the same results as looking for a draw on a battery as I said above with your test light across the posative and negative battery terminals. The light will light as the motor will run when connected to a battery. To check a shift motor for a draw you have to connect a 2 to 4 watt bulb inline at hthe shift control motor's connector. One bulb for each of the 2 terminals. If they glow you have a draw in the motor. Same as doing a draw test across the disconnected negative battery terminals The ECM picks up this draw and shuts the shift system down. This is the BEST test for a shift contorl motor, plain and simple.
Your Honda dealer is right. They would need your unit to check the ECM. To check the ECM you have to install a different ECM in the unit. There is no tests available across each and every terminal of the ECM, that exist. SInce your unit was under water, It needs to be treated as what Honda terms a flooded shift control motor. In the long run the real only cure is to replace it.
If you trace the 1st gear readout back through the wire harness, it ends up getting a ground through the shift angle sensor. I believe the ECM shuts this system down when it reads a draw within the shift control motor. It is just one way I have become aquainted with reading a meter on a pre 2002 unit when they have a shift motor issue. A diagnosis step you could say as I have had to replace the motor in every unit that has displayed the meter functioning as you have described.

----- Gimpster -----

 

Sorry i've been gone for awhile. Wow, That's an extensive analysis. It sounds logical! I am going to give it a try. I'll let you know how I make out.
I really appreciate your advice!!!!!!

 

Well, I know its been a while but I just wanted to give you an update. You were right. The control motor test was giving me a false positive. I replced the control motor and she shifted. Just have to put all the parts back together and get it back on the trail.
I really appreciate your advice. I would still be chasing if I had not considered what you said and so logically explained. I made a note in my manual and will pass this gem of wisdom on to anyone who has the same problem!

 

My '98 450es had the same problem and I was ready to fork out the money for a new ECM until I came across this thread.
I put in a new control motor instead and now all is well.

Thanks a million guys.

 

This is the first time I saw this thread .. We've only ever put a couple of ECU's on the 1998-01 TRX450 .. Shift control motors are common to fail mostly because of dirty brushes/commutator bars ..
These are the tools I use for pre 2002 TRX450ES ..

takes place of shift control motor






takes place of angle sensor