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03 Foreman ES Reverse gear display problem

2K views 4 replies 2 participants last post by  Kirk 
#1 · (Edited)
I recently bought an 03 Foreman ES with an intermittent problem displaying the "R" when in reverse gear.

The unit always shifts to reverse gear just fine, but about 95% of the time only shows a "-" on the meter when "R" should be displayed. (The Reverse lamp on the meter is also off.)

I've checked the gear position switch and wiring all the way to the ECU, and everything checks out fine. I've even tried shorting the grey wire to ground while in Reverse, and it makes no difference in the display. Occasionally, the "R" displays correctly on the meter, and the Reverse lamp lights as it should, but most of the time it just shows "-" when in reverse gear. This would lead me to think that the ECU is faulty, but I wouldn't expect a bad ECU to be intermittent.

Gears N-1-2-3-4-5 display correctly 100% of the time, and no error code is ever generated.
Although this doesn't affect the operation, I'd like to get this nuisance corrected if possible.

Any suggestions on where to look next would be greatly appreciated!

Thanks,
Kirk
 
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#2 ·
Welcome to the forum.


I would take apart the plug where the gear position switch plugs into the harness (under right side of the seat on my 500's)


I've had a Rancher that wouldn't pick up first gear, and a Foreman that wouldn't pick up third gear because the pins in that connector weren't making a good connection. The Foreman was intermittent, the Rancher wouldn't read 1st gear till I fixed the connection on that particular pin.
 
#3 ·
Thanks for your response.

As you must have missed in my original post, I've already traced the reverse wire all the way back to the ECU. (through the connector you mention) The signal is switching to ground when in reverse, (reading 0v when under power) when the transmission is shifted into reverse.

The schematic shows that this same grey wire extends up to the meter, and the ECU provides a separate signal to the meter to turn on the reverse lamp. Therefore, this would appear to be an ECU fault, but it's strange that occasionally it all works correctly. (I wouldn't expect an electronic device like the ECU to fail intermittently, which is why I still suspect a connection problem somewhere else.) I don't have any experience troubleshooting Honda ATVs, but I do have experience with industrial electronics. I hate to buy an ECU, not knowing for sure that's the problem.

I was hoping that someone here might have some additional insight with a problem like this, and could provide suggestions beyond what is in the service manual.

Thanks again!
 
#4 ·
Ah, sorry about that. I did kinda skim over that. I saw "intermittent" and instantly thought "bad connection"




If the signal always shows ground back to the ECU, I would think ECU, but it is strange that it happens intermittently.


Have you checked the wire going to the indicator both when it's working and when it's not working? Seems like that signal would be coming out of the ECU so if it's consistent going into the ECU, and coming out of the ECU when it's displaying correctly, and consistent going into the ECU but there is not the same signal coming out of the ECU when it's not working, that the ECU would be the culprit.


I would suggest unhooking the ECU, cleaning the crap out of the connections, and using some dialectic grease before you buy an ECU.


I had a throttle position sensor on one of mine that checked out, so the FSM said "bad ECU". I replaced only to find the same issue. It apparently was one pin on the ECU plug that wasn't making a good connection, and simply cleaning the connections fixed the problem.
 
#5 ·
Found the Problem!

After finding no issues with the gear position switch, harness and related connectors; this afternoon I ended up taking the meter apart.

Inside the meter, there are two plug-in connectors on the main circuit board that provide all the connections to the bike harness. I separated the smaller connector first (no surprises); but before I could separate the second (larger) connector, the both halves of the connector just fell free from the circuit board!

The half of the connector that should have been soldered into the circuit board had never been soldered from the factory! It was making contact (intermittently) just by its pins contacting the plated-through holes in the board.

It's amazing that an intermittent Reverse indicator was the only problem!

Got out the soldering iron, and soldered the connector half in place (as it should have been from the factory), and the problem is now corrected.

Must have been a late Friday afternoon assembly/inspection at the factory!
 
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