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Discussion Starter #1
I have a 2004 Honda Foreman 450 ES. It first had code 5. Replaced the angle sensor and then replaced the shift motor. After that it switched to code 3. Went through the service manual steps for code 3 and it says bad ECU. Replaced ECU and it switches between code 3 and code 5. Warrantied new ECU and still wont shift.

I have power and ground coming into the 5P plug on the ECU, but no power out of the ECU when needed to shift.

I can manually put power and ground to the shift motor wires at the 5P plug in and it will shift up and down through all the gears and display the correct gear on the dash.

I have continuity when needed on the shift switches, Also have 5 volts into the switch and out on whichever button is pressed.

Angle sensor measures 4.6k ohms and the wires have continuity to the ECU.

What else is part of the shift system that may because the shift system not to work?
 

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Discussion Starter #2
Also I have pulled all the electric connections apart and cleaned them and then dielectric greased them. Also unbolted the grounds under the gas tank on the frame and cleaned the frame connection and reattached. Also have adjusted the clutch and it all made no difference.
 

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Discussion Starter #3 (Edited)
So i got the speedometer fixed. I was only getting 1 volt on the black blue to the speed sensor. I Bent the terminal on the computer slightly and now i have 12 volts and the speedo works. Still no shifting tho. The battery tests good but is 4 years old so I'm gonna replace that and its charging at 14.8-15.0 volts on the old battery. So if it still doesn't shift and is charging that high after the new battery I will replace the voltage regulator.

**Edit: New battery is same thing. 15v at idle and 14.6 when you rev it up with headlight on. Manual says spec is 14.7-15.5v at 5000rpm
 

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Discussion Starter #5
So I tried a used harness and voltage regulator off of a running ATV. Still doesn't work, i only get code 5 now tho. I went through all the service manual steps for code 5 and it says ECU. Which I have a new one and its still the same. If i unplug the 5p connector at the computer the shift light will quit flashing. If i unplug the 2p connector at the shift motor but leave the 5p plugged it, it still flashes. only when i unplug the 5p connector does it stop flashing.
 

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Discussion Starter #6
So I decide to check the angle sensor after the harness swap. I have 3 angle sensors (1 honda brand and 2 sensortech brand) But none of them seem to work correctly.

Spec is:

Neutral: 4-6k ohms
Upshift: <.4ohm change
Downshift: > .6ohm change

Honda sensor:
Off the ATV: 3.8k ohms
Mounted in neutral: .5m ohms

2004 Sensortech sensor:
Mounted in neutral: 4.57k ohms
upshift: 4.57k ohms no change
Downshift: 4.57k ohms no change

2005 Sensortech sensor:
Mounted in neutral: 4.47k ohms
Upshift: 4.47k ohms no change
Downshift: 4.46k ohms Slight change

Could all 3 new sensors really be bad? This is all tested key off with sensor unhooked.
 

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Discussion Starter #8
Well I gave up and made my own harness with 4 relays and reuse the stock handlebar buttons to shift. I had replaced everything except the dash display.
 
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