Hello all, new member here. I have a 2004 Foreman 450ES that I've had about a year. In that year I've exhausted all efforts to correct a problem with my ES. I will state the problem then run down the list of changed parts and trouble shooting steps I've done that has yet to correct this problem. Seeking serious help!

Shifts fine through all gears up and down while idling, when you drive it, it will shift but will intermittently fault out with the 3 flash code for Angle Sensor. Usually does it within the first run up through the gears. Typically any gear, 3rd mostly, but it ALWAYS faults out. It easily resets with off/on of the ignition, sometimes when done fast enough, even while I'm driving, only to fault out again within minutes. Installed a manual shift lever and the transmission shifts just fine. The meter shows speed and gear position just fine. The only issue with the meter is that the odo reads 999999, but Honda says that's a meter issue and not related to the ES.

I have changed, cleaned and/or trouble shot the following with the use of the Honda service manual:
-Replaced the Angle sensor X2
-Disassembled the original shift motor and cleaned the internals
-Adjusted the clutch X100
-Changed the Shift Motor
-Installed New Battery, voltage is good
-Changed fuses
-Cleaned all electrical connections and dielectric greased
-Tested all wiring in the Angle Sensor Circuit including the ECU, all good!

After performing all the Honda manual troubleshooting steps it then states, "Change the ECU and begin troubleshooting again." which tells me, that not even Honda has a clue whats wrong at this point. A new ECU is a couple hundred dollars and according to online factory videos explaining how the ES system works, if the ECU resets than the ECU is working as it should. So that may not even do anything.

I've searched the internet for months for my particular issue and I either can't find anyone with this exact issue or they have the same but get no resolution. Honda dealer says to bring it in, no way that that's happening, way too much $$$$.
PLEASE HELP fellow Honda owners?????

 

It is looking like your ECU is bad. If you changed angle sensors and are sure all wires are OK this is all it can be, but an intermitent fault in wiring is extremely difficult to find so you do need to be certain that it is not a wiring fault before spending lots of cash. I did once have an ES that broke the shaft that drives the angle sensor but that fault coded on the first shift every time.

The alternative is to fit a manual shift, you need to remove one of the reduction gears for the shift motor, I believe special hexagonal pedals are available in the US, in the UK we use a socket welded to an old pedal, they tend to wear and get sloppy though. The display will fault code all the time too.

 

I know merryman, it is looking like a new ECU is in order. My only hesitation is the Honda info referring to indications for a bad ECU are ruling it out, and the fact that its an awfully expensive part to throw at it on a hunch. When I spoke to my local Honda dealer, which were little to no help, the only thing that they did say that seemed to make any sense was the ECUs typically are either good or bad not intermittent as in the case of what I have going on. Like I said, it almost always electrically shifts fine at idle. Its mainly just once you start driving. That had me thinking speed sensor, but once again, Honda says if you have speed indicated on the digital meter than you can rule that out too. Just like the gear position sensor, if you have gear indication displayed than it also is working as advertised.

This video is for a few earlier years than my 04 cause my ECU does provide fault codes, and my speed sensor is mounted on my front diff not the back of the motor, but all other concepts of the ES system is exactly the same.
The only other strange bit of info is that sometimes the code will be flashing right upon turning the ignition on. If I take the manual shift lever, which is now permanently mounted, and wiggle the shifter up and down within nuetral, key off/on, its like the angle sensor finds a sweet spot and will then allow the ECU to reset. Sometimes it might take a couple tries but it eventually resets. That was making me think that maybe something in the mechanical linkage to the clutch is worn out and the shaft for the angle sensor is not returning to the neutral position like it should. But when I test the ohm readings of the angle sensor by manually shifting it with my hand through all gears up and down, all readings are within the 0-5 ohm range, which makes me rule out that idea.

oh...forgot to mention, cause I know there are guys that have found moisture causing sticking switch problems. I've also disassembled the gear shift switches, cleaned everything and all are working as advertised.

 

Have you checked the battery voltage with the engine running, a faulty regulator will supply the wrong voltage to the ECU which then fault codes.

The 4WD system has a separate fault code system which is dependent on another two speed sensors in the front diff, this does code when it reaches a certain speed if one sensor goes bad.

Check those gears in the shift motor reduction box, I've had those break a tooth, and personally, I would leave one out and use the foot change from now on.

 

Heven't checked the voltage to the ECU with the atv running. Figured a brand new battery would have me covered for required 12 volts. Plus all lights a bright with no bleed off like i have a voltage draw or loss, but I will check it.

Funny you mention about the reduction gears....cause I've been thinking about those as a possible cause for a while now, but I've never heard anyone else say they have had a problem with them. I looked at them when I changed the motor and all looked fine, but could it be a case where the have excessive wear?

 

So I swung by my local Honda dealer today for one last attempt at some technical insight. They actually informed me of something that MIGHT be a possible cause to my problem. Since the angle sensor had been physically broken when I bought this machine, it has only ever had replacement Angle Sensors installed. So wondering if anyone else has run into this and if the symptoms I have indicative of this problem.
They informed me of a Honda factory service bulliten regarding defective Mexican made Angle Sensors, of which is what I have installed in my machine for the second time, and that there is a replacement out there as a fix. Love to get anyones thoughts on this issue and if this could be my problem? I've ordered one of the replacement ones anyone.

 

Those Mexican sensors were withdrawn at least four years ago, probably more, if they have been selling you Mexican sensors they should give you a later replacement, free of charge.

 

The Honda Service Bulliten they gave me is dated March 2014. It actually has a picture of the suspect sensor and the new replacement. The picture of the bad one is exactly what I have in my machine. Maybe this is something else that has become a problem with them. The body on the new sensors look a bit different. Supposed to get the new one this week. Guess I'll keep you posted if it fixes my problem. God, I hope!

 

In the "trade" we heard about the faulty Mexican sensors years ago. Honda may have only sent the bulletin out this year, but knew about it circa 2010.

 

I had seen so little on-line talk about it that I assumed it had been something that had happened years ago, and any OEM Angle Sensor I would've ordered from a reputable parts dealer would be, by now, the right part. Combined with the fact that reading all the online talk about trouble shooting Angle Sensor faults like mine, I hadn't read one thing saying a faulty, recalled, replacement sensor would cause the issue.