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gsxr1181

Stuck in limp mode in neutral and drive, but full throttle reverse?

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I have been directed over here from another forum to help me out with a 2002 Honda Rubicon 500 I'm trying to fix for a friend.  Here is a copy and paste from my post. 

 

I have been given a 2002 Honda Rubicon ES to work on, and I am having an issue with getting this thing to idle up in neutral and forward gear. However, reverse works great, and the engine will go full throttle while in R.  It acts like it's in a "Limp Mode" in neutral and forward gears.

I have checked the angle sensor which is new, ohm out, and clocked correctly. Electric motor is fine, and everything will shift in ESP 1-5 no problem. But will not shift automatically in D1 or D2, as it seems to be in limp mode while on neutral, L and H. (5 MPH MAX in D1 & D2)

I have done the initial setup process exactly by the service manual, and also made sure to clear codes, even though I have no codes showing. I've kind of hit a wall, and have checked everything in the service manual including the gear shift position sensor, speed sensor, TPS, Speed Sensor, ect. Including checking the wiring going to the ECM. Battery is new, and have 14.5V while running.  I have also found another ECM to try.  I swapped it, initialized it, made sure their were no codes, and the issue is still present.  So it's not an ECM or electric issue I feel like.

 



Anyone's help is appreciated if someone has any suggestions on what I can do, or what I've missed.  I've been staring at this thing for 3 days, and I'm at a complete loss on what to do next.

 

 

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Welcome GSXR  to ATVHonda , we do have some Rubicon guys here who might know about that limp mode , @toodeep @jeepwm69   limp mode all  I know is when I bang my shin on the floorboards 

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Welcome. I'm going to guess the gear indicator is working normally and not displaying the -- ? You should not be able to go full throttle in reverse as it should limit it, like the problem you are having with neutral and forward. Has there been any other work done to this machine? I would have said camshaft or the cam holder bearing was bad but the full throttle reverse makes a problem with that thought. 

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Sounds like a gear position switch issue to me.  That is what tells the ECU to limit revs in Reverse, and also if the ECU can't tell what gear it's in it goes into limp mode, right?

 

Second the "is the gear indicator working normally" question.

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Posted (edited)
6 hours ago, jeepwm69 said:

Sounds like a gear position switch issue to me.  That is what tells the ECU to limit revs in Reverse, and also if the ECU can't tell what gear it's in it goes into limp mode, right?

 

Second the "is the gear indicator working normally" question.

Yes the gear indicator is working correctly.  I did check the gear position sensor at the harness.  It shows ground in the correct gear, and open on the gears it's not in.  So it's working correctly as far as the check in the service manual.

Edited by gsxr1181

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On 4/13/2021 at 6:21 PM, gsxr1181 said:

I have been directed over here from another forum to help me out with a 2002 Honda Rubicon 500 I'm trying to fix for a friend.  Here is a copy and paste from my post. 

 

I have been given a 2002 Honda Rubicon ES to work on, and I am having an issue with getting this thing to idle up in neutral and forward gear. However, reverse works great, and the engine will go full throttle while in R.  It acts like it's in a "Limp Mode" in neutral and forward gears.

I have checked the angle sensor which is new, ohm out, and clocked correctly. Electric motor is fine, and everything will shift in ESP 1-5 no problem. But will not shift automatically in D1 or D2, as it seems to be in limp mode while on neutral, L and H. (5 MPH MAX in D1 & D2)

I have done the initial setup process exactly by the service manual, and also made sure to clear codes, even though I have no codes showing. I've kind of hit a wall, and have checked everything in the service manual including the gear shift position sensor, speed sensor, TPS, Speed Sensor, ect. Including checking the wiring going to the ECM. Battery is new, and have 14.5V while running.  I have also found another ECM to try.  I swapped it, initialized it, made sure their were no codes, and the issue is still present.  So it's not an ECM or electric issue I feel like.

 



Anyone's help is appreciated if someone has any suggestions on what I can do, or what I've missed.  I've been staring at this thing for 3 days, and I'm at a complete loss on what to do next.

 

 

 

OEM angle sensor or ebay/amazon angle sensor?

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42 minutes ago, jeepwm69 said:

 

OEM angle sensor or ebay/amazon angle sensor?

I'm going to say eBay sensor. The owner who I'm trying to fix this for bought the sensor, and I'm assuming it's eBay knowing him.  However I do have the original sensor, and it checks out ok.  I even put the original back in, and it's the same issue.

 

Both sensors checked out in spec according to the service manual.  Is there something else I need to try or check?

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Lets clarify limp mode. Is it like hitting a rev limiter (bing, bing, bing, bing) or like at the end of a power band/reduced power (blahhhhhh)?

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On 4/15/2021 at 12:29 PM, toodeep said:

Lets clarify limp mode. Is it like hitting a rev limiter (bing, bing, bing, bing) or like at the end of a power band/reduced power (blahhhhhh)?

It's more of a bing bing.  Almost like a two step on a turbo drag car, but just above idle. 

 

If I can later, I will attempt to post a video what what's going on.  Unfortunately I've been working the past two days and haven't been able to mess with it.  I'm going to try and dig into it later this evening.

 

 

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I recorded a quick video of the issue.  Maybe this will help understand what's going on. 

 

 

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I haven't worked much on the older Rubicons so I'm throwing darts here, but to me definitely sensor/electrical vs mechanical. 

 

Brake switches on the newer bikes will cause that, but I don't think the 01-04 Rubicons have brake lights. 

 

Might have something to do with the switches on the actual shifter, although it's usually the opposite on a Rubicon (works fine in forwards, will sputter in reverse if that switch is bad on the shifter).

 

 

 

 

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When you initialized (key off holding buttons, key on release then shift up, down, up- no throttle to full throttle to no throttle- shift motor cycles then N appears on the screen) it you could hear the shift motor cycle at the end of it correct?

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6 hours ago, jeepwm69 said:

I haven't worked much on the older Rubicons so I'm throwing darts here, but to me definitely sensor/electrical vs mechanical. 

 

Brake switches on the newer bikes will cause that, but I don't think the 01-04 Rubicons have brake lights. 

 

Might have something to do with the switches on the actual shifter, although it's usually the opposite on a Rubicon (works fine in forwards, will sputter in reverse if that switch is bad on the shifter).

 

 

 

 

It does have front brake switch, but I have tested it to make sure the switch works.  It goes to ground when the lever is pulled in.  It is missing one of the rear tail lights.  But I would hope that wouldn't have anything to do with it. It doesn't have a rear brake switch according to the service manual.

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9 hours ago, toodeep said:

When you initialized (key off holding buttons, key on release then shift up, down, up- no throttle to full throttle to no throttle- shift motor cycles then N appears on the screen) it you could hear the shift motor cycle at the end of it correct?

Yes, I've done that procedure multiple times. I get the motor to cycle, and N appears at the end.

 

I've even unplugged the motor and angle sensor to force it to code as well, just so I could reinitialize everything, and clear out the codes hoping something would happen. Still puzzling.

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Have you inspected the reverse switch - the one attached to the shifter you operate with your hand?

It's found in the service manual on page 22-13.

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Posted (edited)
On 4/21/2021 at 11:14 AM, spock said:

Have you inspected the reverse switch - the one attached to the shifter you operate with your hand?

It's found in the service manual on page 22-13.

Yes it goes to ground when depressed. I even bypassed it manually to make sure it wasn't an intermittent issue.  It works properly, and is activating properly when placed in reverse. 

Edited by gsxr1181

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Posted (edited)

Well, it sounds to me like you've tried everything there is to test. That leaves the Hondamatic itself which is known for failures in those early years.

Strange that it seems different in reverse, but I believe your issue is mechanical and most likely is due to an oil pressure type of malfunction.

Hey, I just noticed that our dogs are looking at each other, haha!

 

 

Edited by spock

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Hi: Have you checked the D1 & D2 switches for continuity?

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On 4/24/2021 at 10:35 AM, spock said:

Well, it sounds to me like you've tried everything there is to test. That leaves the Hondamatic itself which is known for failures in those early years.

Strange that it seems different in reverse, but I believe your issue is mechanical and most likely is due to an oil pressure type of malfunction.

Hey, I just noticed that our dogs are looking at each other, haha!

 

 

 

If it works in reverse, and cuts out in forward, it's an electrical gremlin.  The Hondamatic either works or it doesn't.  That cutting out is something electrical.  Sensor somewhere is kaput.

 

Of course, electrical gremlins can be the hardest for most of us to find, Melatv being one of the few exceptions.

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1 hour ago, jeepwm69 said:

 

If it works in reverse, and cuts out in forward, it's an electrical gremlin.  The Hondamatic either works or it doesn't.  That cutting out is something electrical.  Sensor somewhere is kaput.

 

Of course, electrical gremlins can be the hardest for most of us to find, Melatv being one of the few exceptions.

Yeah, I tend to agree with you on this one. Something electrical is the first thing that comes to mind....the question is, what could cause this but not trigger a fault code?

Very strange! My experience with a failed Hondamatic was one that worked fine when cold, but when fully warmed up it slipped - similar to a bad clutch.

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57 minutes ago, spock said:

My experience with a failed Hondamatic was one that worked fine when cold, but when fully warmed up it slipped - similar to a bad clutch.

 

Good to know.  I haven't had one fail yet, but in most of my reading they make noises, then stop pulling, and they're done.

 

I have a running 05 that I've actually grown quite fond of.  Not having to shift when driving the little one around is nice. 

 

I have a 2013 that I bought last summer that "ran but doesn't pull" for $600, and it came with an 08 500ES "parts bike" with PS that I cleaned up, rebuilt, and sold already.

 

I figured either bad Hondamatic or oil pump chain is off.  It was snorkeled so it will get a full tear down.  The rest of it looked really good though.

 

Out of curiosity I hooked jumper cables to it a few days ago to see how many miles it shows.....2300.

 

 

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