2004 Honda foreman Rubicon 500 stuck in 4th gear?

[Kendallh 3]

So I've just recently acquired my 04 foreman Rubicon 500 knowing that it ran but needed work. How much work, I've no idea! The screen is sun damaged but I cleaned up the connectors and applied dielectric grease which has helped enough to be able to see the display. Upon checking for codes I've seen code 4, which to my knowledge is the tps. I've ordered a new tps and am currently waiting for its arrival. The only other major issue I've found is that the quad only goes into 4th gear. I can clear the code for the tps and it will work in reverse normally without being in limp mode but after a little while it limps again. However going forward it is only ever in 4th, high range or low range. 

 

I thought in limp mode it would only go into 1st gear but I don't know much about these bikes yet. I've checked the shift motor and it spins freely. Am I missing anything? 

[jeepwm69 7,611]

Welcome aboard.  Does it drive in auto mode?

 

You need a good strong battery on these for them to work right.  If you have a good battery on the machine, try initializing the system. 

 

Machine in neutral

Hold up and down shift buttons in and turn key to on position

Hit up, down, up on the shift buttons, then open and close the throttle within 5 seconds.

 

That should re-initialize all the computer crap.

 

See if that changes anything.

[Kendallh 3]

38 minutes ago, jeepwm69 said:

Welcome aboard.  Does it drive in auto mode?

 

You need a good strong battery on these for them to work right.  If you have a good battery on the machine, try initializing the system. 

 

Machine in neutral

Hold up and down shift buttons in and turn key to on position

Hit up, down, up on the shift buttons, then open and close the throttle within 5 seconds.

 

That should re-initialize all the computer crap.

 

See if that changes anything.

Doesn't matter if it's in D1, D2 or EPS it's only ever in 4th gear. I've checked the battery voltage and it's 12.4 with the engine off. Once I crank it up voltage is 13.6. No idea how old this battery is but it seems to be fine. I have noticed, however, the starter does slow down a bit fast during cranking so maybe my battery is a bit tired. 

[jeepwm69 7,611]

3 hours ago, Kendallh said:

Doesn't matter if it's in D1, D2 or EPS it's only ever in 4th gear. I've checked the battery voltage and it's 12.4 with the engine off. Once I crank it up voltage is 13.6. No idea how old this battery is but it seems to be fine. I have noticed, however, the starter does slow down a bit fast during cranking so maybe my battery is a bit tired. 

 

I doubt your battery is the issue if your voltage readings are correct.

 

Did you try initializing the system yet?

[Kendallh 3]

20 minutes ago, jeepwm69 said:

 

I doubt your battery is the issue if your voltage readings are correct.

 

Did you try initializing the system yet?

Yes sir I have. No difference.. 

[jeepwm69 7,611]

It does appear error code 4 is TPS.   Have you downloaded and looked at the factory service manual?  There's a "service manual" button in the toolbar at the top of the page.   The 01-03 Rubicon manual will work for your 04.

 

I haven't had a lot of experience with the Hondamatic machines yet, but am trying to learn on them.   Most likely you have an electrical issue of some sort, but they can be a PITA to troubleshoot.

[Kendallh 3]

3 minutes ago, jeepwm69 said:

It does appear error code 4 is TPS.   Have you downloaded and looked at the factory service manual?  There's a "service manual" button in the toolbar at the top of the page.   The 01-03 Rubicon manual will work for your 04.

 

I haven't had a lot of experience with the Hondamatic machines yet, but am trying to learn on them.   Most likely you have an electrical issue of some sort, but they can be a PITA to troubleshoot.

Will do that now. Won't be free again to troubleshoot the bike till Sunday but maybe I'll find something out in the meantime. Thanks. 

[Kendallh 3]

9 minutes ago, Kendallh said:

Will do that now. Won't be free again to troubleshoot the bike till Sunday but maybe I'll find something out in the meantime. Thanks. 

I looked and found the service manual pdf files, but for the trx500fa (I believe?) the year options are 01-03, 05-08 and I think 05-12. Is 04 an in between year? 

[jeepwm69 7,611]

2 hours ago, Kendallh said:

I looked and found the service manual pdf files, but for the trx500fa (I believe?) the year options are 01-03, 05-08 and I think 05-12. Is 04 an in between year? 

01-04 were the same, and 05-14.

 

that 01-03 manual was just the 2003 dated manual.  The 01-03 is what you should use.

[Kendallh 3]

Okay so I've just received an Amazon carb and water pump. Cleared codes and reset the bike and it shifted great for about twenty seconds. Then it went back into limp mode. It seems whatever gear it's in when it goes into limp mode is the gear it stays in. I've reset the computer a few times and been stuck in first, second, and 5th gear depending on when it decides to limp. It's hard to see my screen at times, and lately my reverse led light has been flickering while in neutral. Not sure what's up with that. 

 

So far I've replaced the shift angle sensor and the leaky carburetor, which came with a tps. I thought about rebuilding the old carb but I don't think it's old, I think it's an Amazon carb as well. Rebuild kit was $30 and a carb was $50 so why not? 

 

There must be something wrong with the tps Amazon makes or something because it's still flashing code 4 on my display. 

[AKATV 822]

Amazon parts most likely =China garbage, which is going to make headaches for you- guaranteed

if that TPS came on an Amazon carb that might be part of your issue

Just out of curiosity, is your speed reading correct on the meter? -If not it, will go into limp mode

I only asked because you said it was hard to see meter at times, you might want to open the speedo

and make sure you dont have water damages in there- if you have flickering LEDs that is a sign for sure

Keep us updated

-AKATV

[Kendallh 3]

When I first got the bike home the screen was completely blank so I took it apart and sprayed the connectors with contact cleaner, then applied lithium grease to keep moisture out. Since then the screen is working, but hard to see due to sun damage and scratches. The reverse led didn't start flickering till a week after I cleaned the connections. Only thing I didn't do is take the speedo screen apart, scared to try to do that and it not work at all. Previous owner had put what looks to be caulk around the wires on the back side of the screen though. As far as I can tell the speedo is accurate. 

 

I did notice that even with the key off the screen still has a display though, and it will sometimes show different speeds with the key off. 

 

Did I mention I HATE electrical stuff? Haha! 

 

Sometimes when I turn the key on, the gear indicator will be blank, or sometimes it flashes the gear that it's in plus D1, D2 and ESP flashing as well. 

 

As far as cheap Chinese parts and oem, where might I find an oem tps or carb assembly? I've done some looking on Google and was pretty disheartened at the price of even used oem parts.

 

Also did some digging around for maybe a four wheeler salvage place nearby but no such luck. 

[jeepwm69 7,611]

Well @AKATV actually rebuilds meters and does an amazing job of it BUT once water gets in there it usually fries the circuit board where they aren't worth trying to fix. 

 

That sunburnt screen he can have looking like new though if the board isn't fried.

 

 

[AKATV 822]

You at least want to open top cover to make sure there is no water damage inside on the circuit board

If there is, it just get worse from there as it dries/corrodes and damages the circuit board and components

-AKATV

[Kendallh 3]

Okay I'll check it out. Will update in a little bit to let y'all know what I find. 

[Kendallh 3]

Unfortunately there was water sitting inside the speedo. I'm not circuit board savvy so I'm not sure if it's too far gone or salvageable. Pictures attached. The first picture with the screen on is while the key is off. 

[AKATV 822]

Thanks for the pictures

Actually, that’s not in too bad of shape

It appears to be functioning normally

You do not have anything showing up in the gear position area, but that most likely is a sensor or wiring issue

I’m assuming that your buttons work and if your speed is registering properly, then you most likely don’t have any major issues with the circuit card or display

I do see some sun damage to the upper polarizing film but since it’s still readable, it’s purely cosmetic

If your top plastic cover is cloudy, you can most likely polish it out with an automotive plastic headlight polishing kit they sell them at Walmart and similar for between 10 and $20  and with a little bit of elbow grease I have had many customers get the top covers as clear as new

If you have any other questions or need any additional information, just let us know

-AKATV

 

[Kendallh 3]

Thank you AKATV for looking. My concern is that the display is on whether the key is off or on. The gear indicator seems to work, mostly, but I'm still having issues with my tps so it mostly flashes D1, D2, ESP - - 

 

Ice found an oem carburetor on partzilla for $300. Just bought and installed a cheap Amazon carb. It runs but the tps won't register with the ecm or something. I've disconnected all harness connectors and sprayed them with electric cleaner and applied dielectric grease. All pins are tight and clean so it's most likely the Amazon tps. 

 

On partzilla an oem tps is $150, whereas the whole carb assembly is $300, so I'm torn between going all oem or just trying the tps. 

[AKATV 822]

You might want to double check your key switch to make sure it’s turning power off

if so, then it sounds like you might have a short down on your lower speedometer plug possibly
You want to check on the back of that circuit card- There’s a red/ black wire, which is a constant power to hold up your clock memory

Your other power wire is a Brown/black wire which is your key on power

make sure you use the green wire as ground

You want to make sure you have constant power at the red/black wire and that you only have power at the brown/black wire when you turn the key on

If you find that you have power at the brown/black wire with key off, you might want to check your lower plug to make sure that the pins inside the plug or not water damaged and corroded shorting power down below.

Also, keep an eye open while you’re looking around for any hack job wiring, mouse chewing, etc..

Let us know what you find

-AKATV

[Kendallh 3]

[Kendallh 3]

First picture is red/black wire key off 

 

Second picture is brown/black wire key off 

 

Third picture is brown/black wire key on 

 

I looked over the pins to make sure they were straight and all seems well. 

The screen was blank when I looked at it, key off or on. I unplugged the 9 pin connector and reinstalled it and the screen was displaying again, key off and on. 

[AKATV 822]

Thanks for the update
Obviously, somehow power is  is making its way from the red/black constant power over to the brown/black wire  power circuit somewhere further down the line on the circuit board, 

You might want to check the speedometer plug down below just in case there’s something funny going on down there, if not, you could very well have a faulty circuit card/ circuit

-AKATV

 

 

[Kendallh 3]

10-4 I'll check it out when I can. Running out of daylight today. 

[jeepwm69 7,611]

@Kendallh, looks like the 04 carb is a one year specific carb.  

 

I don't think a TPS will cause limp mode, but it very well might on a Rubicon.  I had a TPS code on my footshift Foreman and it didn't change function any, just annoying error code.  I did the troubleshooting on the TPS and it was in spec.  Ended up replacing the ECU and still had the error code.  Plugged the old ECU back in and the code went away.  Apparently I had a bit of frosting/corrosion on the ECU pins and plugging and unplugging several times cleaned them enough to make the TPS code go away.   Even with an aftermarket TPS if you get good readings you shouldn't get a code.   If your TPS measures good, I'd clean connections at ECU and at TPS and check for continuity on those wires.

 

Honda uses a lot of different part numbers and some of them interchange, and some do not, regardless of what the "related fitment" shows.

 

I looked at the 05-14 Rubicon carbs and it appears to maybe be a slight difference in the main jet size (158 is offered for both carbs, but the 04 has an optional 152 while the 05-14 has an optional 162)

2004

https://www.partzilla.com/catalog/honda/atv/2004/trx500fa-a-fourtrax-foreman-rubicon/carburetor

2011

https://www.partzilla.com/catalog/honda/atv/2011/trx500fa-a-fourtrax-foreman-rubicon/carburetor

 

The TPS also has a slightly different part number.   That said, I checked the TPS readings in both versions of the factory service manual and both call for more or less the same readings for a "good" TPS.

 

04 has .5 closed to 3.5-5.5 ohms opened

05-14 has .5 closed to 4-6 ohms opened

 

My point?  You can likely use a newer carb that will work fine, still going OEM, but from a slightly different year Rubicon.

 

I'll PM you one I got fairly cheap that was OEM and works perfectly on my 2012 Rubicon.   The part number does not pull up anywhere in schematics that I've found, and @toodeep said it was likely a Canadian part number, but he thought it was a Rubicon carb, and when I tried it it worked perfectly.

 

I happen to have an 04 carb in my yard, and a new Rubicon carb somewhere in my shop (I ordered an extra).   I can take some pics of them side by side for comparison.

 

 

[Kendallh 3]

Update

 

Big thanks to jeepwm69, I ordered an oem carb and installed on the bike. Reset the codes and the bike runs through all gears in every setting, including ESP. 

 

Still having issues with the screen going blank intermittently but otherwise the bike is operational now. 

 

 

Just goes to show that cheaper isn't always better!