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450FM, no neutral light issue

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Briefly touched on this in my build thread, but now it really has me scratching my head.

 

Originally I had the gear position switch plugged into the carb bowl heater plug, and vice versa.  That gave me a dim reverse and neutral lights both.

 

Figured out I had the plugs wrong, fixed that, and now no neutral or reverse lights.  Tried running a jumper from batt negative to each wire on the plug where the gear position switch goes to the main harness.  Nothing. 
 

Today I ran a jumper from batt negative to the green/red tracer wire going to the meter, as I intend to try to add a “start in gear with brake lever squeezed” mod to this machine.

 

With green/red wire going to the meter grounded, both neutral and reverse lights light up.  It will turn over and start at that point, but even with the gear position switch unplugged from the main harness, that’s still what I get.  Meter is brand new.

 

Anyone have any ideas @retro @Melatv @AKATV

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6 hours ago, jeepwm69 said:

Briefly touched on this in my build thread, but now it really has me scratching my head.

 

Originally I had the gear position switch plugged into the carb bowl heater plug, and vice versa.  That gave me a dim reverse and neutral lights both.

 

Figured out I had the plugs wrong, fixed that, and now no neutral or reverse lights.  Tried running a jumper from batt negative to each wire on the plug where the gear position switch goes to the main harness.  Nothing. 
 

Today I ran a jumper from batt negative to the green/red tracer wire going to the meter, as I intend to try to add a “start in gear with brake lever squeezed” mod to this machine.

 

With green/red wire going to the meter grounded, both neutral and reverse lights light up.  It will turn over and start at that point, but even with the gear position switch unplugged from the main harness, that’s still what I get.  Meter is brand new.

 

Anyone have any ideas @retro @Melatv @AKATV

with key on, use a 12 vdc test light, grounded to battery on neg side, then poke the neutral connector on harness side leading to gear position switch, it should light up when you probe the connector. most honda's neutral wire on harness side is '' hot '' when key is turn on leading to gear position switch. be sure to re-check all fuses in fuse box to make sure they are getting power across the fuse coming in, and going out.

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4 hours ago, shadetree said:

with key on, use a 12 vdc test light, grounded to battery on neg side, then poke the neutral connector on harness side leading to gear position switch, it should light up when you probe the connector. most honda's neutral wire on harness side is '' hot '' when key is turn on leading to gear position switch. be sure to re-check all fuses in fuse box to make sure they are getting power across the fuse coming in, and going out.


Test light comes on with clip on battery pos and probe on the green (neutral) wire coming off the switch.  That’s with bike in neutral.

 

Light also comes on with probe on the other (reverse) wire though, with the bike in neutral.

 

Switch is likely bad, and I’ve gotta try to find one since they are discontinued.

 

That’s why I unplugged the switch from the main harness snd tried grounding the green/red wire to the meter.  Plan is to hook up a start-in-gear mod and grounding that wire should have made the neutral light come on.  I can’t figure out why the reverse light is also on.

 

 

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Posted (edited)

 

Last time i had both reverse and neutral light come on it was a blown fuse believe it or not-I cant remember which one, but it also caused a no spark condition? so IGN?

The only way for them both to come on would be (somehow) for the wires or contact points to get ground signal since other side of circuit is hot and just require a grong to illuminate each light

Since meter is new its most likely fuse, or wiring issue-you can jumper the key switch connector to elimate switch if you think you might have an issue there

The meter needs 2 sources of 12 volts to properly power up

green is ground and then 12volts + at red/black wire and 12 volts at black/brown wire

One is hot all the time for (clock memory) and one is key on voltage to power up meter cpu circuit

green/red wire is neutral

gray wire is reverse

I'm sure its something simple-might have blown a diode on the circuit board hooking up carb heater BUT I believe that its temperature controlled and circuit should not have been even powered up down in your neck of the woods -OR mine even lol, I THINK that circuit closes and powers the heater at at 40 -ish degrees or so-just guessing on temp

Not sure how disassembled bike is but if you can get to the gray speedometer plug and unplug it, put 12 volts on the red/black and black/brown wire on speedo harness and then ground your green/red N pin to see if only the N light comes on then

If so, we need to backtrace and find why the green/red neutral and gray for reverse are causing an issue

If they do both come on you might have zapped the speed -doubtful but possible

 

 

Edited by AKATV
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5 hours ago, jeepwm69 said:


Test light comes on with clip on battery pos and probe on the green (neutral) wire coming off the switch.  That’s with bike in neutral.

 

Light also comes on with probe on the other (reverse) wire though, with the bike in neutral.

 

Switch is likely bad, and I’ve gotta try to find one since they are discontinued.

 

That’s why I unplugged the switch from the main harness snd tried grounding the green/red wire to the meter.  Plan is to hook up a start-in-gear mod and grounding that wire should have made the neutral light come on.  I can’t figure out why the reverse light is also on.

 

 

do not clip the test light to the battery pos !!!..it goes to battery ground !!!, harness side is always hot when key is on, did you miss the short yellow bus today ??..lol.

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If you are looking for a ground , then putting the clip side of the test light on positive  is  my go to test procedure 

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32 minutes ago, shadetree said:

do not clip the test light to the battery pos !!!..it goes to battery ground !!!, harness side is always hot when key is on, did you miss the short yellow bus today ??..lol.

 

Am I missing something here?  According to this, when machine is in neutral, it should have continuity to ground, which means the neutral wire should be grounded when the bike is in neutral.

 

Crap I hate electrical stuff!

450.png

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Posted (edited)

I’m not sure where things are getting goofy here but the machine sends a ground signal through the gear position switch so if you’re connecting to the negative terminal and touching either the neutral wire which is the light green with red or the gray wire which is reverse all you’re doing is simulating the gear position switch

The LED sides are always hot waiting for a ground to make them Illuminate so jeep is on track

If I’m missing something or misinterpreting something let me know I’ve been out in the heat for a while

Edited by AKATV

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58 minutes ago, AKATV said:

I’m not sure where things are getting goofy here but the machine sends a ground signal through the gear position switch so if you’re connecting to the negative terminal and touching either the neutral wire which is the light green with red or the gray wire which is reverse all you’re doing is simulating the gear position switch

The LED sides are always hot waiting for a ground to make them Illuminate so jeep is on track

If I’m missing something or misinterpreting something let me know I’ve been out in the heat for a while


that’s my interpretation as well. Which means both the reverse and the neutral lights are getting power all the time if they are both lighting up when I ground that green and red tracer going to the meter.

 

Gotta love working on a bike that’s been sitting in the weather  for years!

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Somewhere in the middle of my last rambling post I was trying to say just unplug your speedometer and power up at the speedometer gray plug

See if reverse and neutral come on at the same time when you ground out the green with red tracer -if so it’s your speedo- if not it’s your harness -ish

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1 hour ago, AKATV said:

I’m not sure where things are getting goofy here but the machine sends a ground signal through the gear position switch so if you’re connecting to the negative terminal and touching either the neutral wire which is the light green with red or the gray wire which is reverse all you’re doing is simulating the gear position switch

The LED sides are always hot waiting for a ground to make them Illuminate so jeep is on track

If I’m missing something or misinterpreting something let me know I’ve been out in the heat for a while

you are correct, the gear position switch acts like a ground contact. when the hot side ( wire harness ) see's 12vdc to the switch, and you are sure you are in neutral ?, what you are doing is grounding the switch, this in turn lights up the dash neutral light. in other words..like i said..the harness side is hot at all times when the key is on. the way i test my switches, i clip the test light to the ground side on battery, then i probe the harness side after i turn key on, if my test light light's up ?, then this tells me i am getting 12vdc to the switch, but the switch is not grounding like it should..and lighting dash light. you can not clip test light to pos terminal on battery, and probe harness side..but you can probe the switch side to see if it is grounded when in neutral ? . it all depends on which way i am checking for either power to switch ?, or switch to ground ?..

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1 hour ago, jeepwm69 said:

 

Am I missing something here?  According to this, when machine is in neutral, it should have continuity to ground, which means the neutral wire should be grounded when the bike is in neutral.

 

Crap I hate electrical stuff!

450.png

lol..i hate it too...but...its really simple to understand on this problem.

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I am using the wiring diagram from the FSM.... So I joined the two pages of the wiring diagram shown in the FSM into one image for easier reading. Here is what I'm working with:

 

after-01-wiring.png

 

Download this PNG and open it on your computer if your eyeballs like large images. 😀

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In your build thread you tested the GP switch and it appears to be bad as you said:

 

Quote

Checked the two wire neutral safety switch and did not test good if I’m testing it properly.

 

Checked for continuity between green and red wire and battery ground with it in neutral and got nothing.

 

Checked for continuity between grey wire and battery ground with it in reverse and got nothing.

 

Checked for continuity with my two probes put together and have continuity so that tells me my meter is working properly.

 

so bad switch?…..not so fast

 

So next up lets check the flyback voltage protection diode that is located inside the fuse box. In the image below the red arrow indicates the normally allowed direction of current flow through the diode from the Y/R wire to the Lg/R wire. A diode acts like a one-way check valve so current should not flow in the opposite direction (from Lg/R wire to the Y/R wire).

 

You can test that diode by setting your meter to continuity mode and hold the red positive meter lead on the Y/R wire side diode terminal, and hold the black negative meter lead on the Lg/R wire side diode terminal. There should be continuity indicated on the meter. If no continuity is indicated then the diode is open circuit and must be replaced.

 

Now swap your two test leads to test for continuity through the diode in the opposite current flow direction. There should be no continuity indicated on the meter. If continuity is indicated then the diode is shorted andmust be replaced.

 

Let us know how that test turns out before we continue.....

 

flyback-diode-current-flow-direction.png

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13 minutes ago, retro said:

In your build thread you tested the GP switch and it appears to be bad as you said:

 

 

So next up lets check the flyback voltage protection diode that is located inside the fuse box. In the image below the red arrow indicates the normally allowed direction of current flow through the diode from the Y/R wire to the Lg/R wire. A diode acts like a one-way check valve so current should not flow in the opposite direction (from Lg/R wire to the Y/R wire).

 

You can test that diode by setting your meter to continuity mode and hold the red positive meter lead on the Y/R wire side diode terminal, and hold the black negative meter lead on the Lg/R wire side diode terminal. There should be continuity indicated on the meter. If no continuity is indicated then the diode is open circuit and must be replaced.

 

Now swap your two test leads to test for continuity through the diode in the opposite current flow direction. There should be no continuity indicated on the meter. If continuity is indicated then the diode is shorted andmust be replaced.

 

Let us know how that test turns out before we continue.....

 

flyback-diode-current-flow-direction.png

 

Thanks @retro.  Laid up with the stomach bug at the moment, but will hopefully be able to check that in the morning.  My "typhoid Mary" toddler had this yesterday and was nice enough to share.  She's fine today so hopefully just a 24 hour bug.

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Finally went out to try this early this morning.  Been focused on the tractor and household duties

 

I have several old chopped up wiring harnesses around, all of which had that dialed in the fuse box. I tested several of them and none of them show continuity in either direction. Am I doing something wrong?

 

I was putting my multimeter on the ohms setting, red probe on the center terminal coming off of the diode, black probe on the terminal that connects to green wire coming out of the fuse box.

 

Using that method, I checked five different diodes and none of them show continuity in either direction

756FC60B-FEF1-44D3-870C-B231EBC0EE1B.jpeg

353F71E6-06DF-4043-A4A3-15F900BA2D3B.jpeg

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Posted (edited)

Jeep 

you have a diode/continuity  setting on your meter-

its the next one down clockwise from

the “out” setting

you should get a reading in one direction on your diode and when you reverse the probes on the same pins you should get no reading 

I am sure you have a good diode in the pile, I wouldnt think they were all bad

(Just saw retros post above sorry for

excess info)

Edited by AKATV

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6 minutes ago, AKATV said:

Jeep 

you have a diode/continuity  setting on your meter-

its the next one down clockwise from

the “out” setting

you should get a reading in one direction on your diode and when you reverse the probes on the same pins you should get no reading 

I am sure you have a good diode in the pile, I wouldnt think they were all bad

(Just saw retros post above sorry for

excess info)

 

No that's exactly what I needed to know.  Problem is ME, not the diodes LOL.

 

One of these day's I'll learn how to use a something on a multi-meter other than checking volts on batteries.

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So checked 4 different diodes.  All showed 520-535 on the multimeter with it in the mode @AKATV showed me to use. 
 

touching the terminals together resulting in a beep and 000 on the meter.

 

reversing leads left a 1 on the meter the whole time

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Sounds like all your diodes are checking out just fine

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Alright, lets check for a short in the wiring harness. With the ignition key off unplug the following parts:

  • Starter solenoid
  • Two-wire connector on the CDI
  • Gear position switch
  • Meter
  • Remove diode (you just tested) from the fuse box

Then check for continuity between the Lg/R wire and the Grey wire either in the harness-side connector that you unplugged from the gear position switch, OR in the harness side connector that you unplugged from the Meter. There should be no continuity between the LG/R and Grey wires.

 

If the harness tests OK then the Meter becomes the suspect. Test for a shorted LED circuit inside the Meter by following @AKATV advice here:

https://atvhonda.com/topic/2172-450fm-no-neutral-light-issue/?do=findComment&comment=62680

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Thank you sir!  I will try that, but will be tomorrow.

 

Little one is 3 today.  We’re doing Bluey birthday!

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Checking on the light green with red tracer wire and the gray wire on the harness side where the meter plugs in, The one showing on the meter drops to about 015, which appears to show continuity correct? So I have a bad spot in the harness somewhere correct?

 

 

Now the question is, am I better off trying to track down a bad spot in the wiring or replace the harness with a used harness from PSN?

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5 hours ago, jeepwm69 said:

The one showing on the meter drops to about 015, which appears to show continuity correct?

 

I am confused. It's showing resistance.... the exact amount is unknown though because there is no decimal point in that measurement (I expected there to be a decimal point preceding the numbers) and you didn't mention which resistance range the meter was set on.  For the test your meter should be set on Diode & Continuity mode, same mode as you tested those diodes. Then with one test lead poked into the Grey wire and the other test lead poked into the Lg/R inside the harness connector the meter should read open circuit (most meters display an open circuit as: "0L" in Continuity mode). If the meter detects a short circuit it then displays resistance, generally with a decimal point preceding the number of ohms and the meter may also produce a beep sound.

 

You can use the lowest resistance mode scale (on your meter the lowest is the 200 ohms scale) to test for continuity too, if you'd rather, it's the same test as Diode/Continuity mode but without a beep feature. But always report the mode setting you chose to test with along with the measurement (including the decimal point if one is displayed), so we don't have to guess about the resistance scale you're using.

 

On another note.... I am using the wiring diagram that I posted earlier... and I just noticed that the Grey wire is shown joined to the battery positive wire for the taillights on that wiring diagram. So the wiring diagram is in error, it might be useless to us?

 

I see that the Grey wire connects to the 4wd control unit according to the diagram so you should unplug that as well, before testing for shorted wires again.

 

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10 hours ago, retro said:

 

I am confused. It's showing resistance.... the exact amount is unknown though because there is no decimal point in that measurement (I expected there to be a decimal point preceding the numbers) and you didn't mention which resistance range the meter was set on.  For the test your meter should be set on Diode & Continuity mode, same mode as you tested those diodes. Then with one test lead poked into the Grey wire and the other test lead poked into the Lg/R inside the harness connector the meter should read open circuit (most meters display an open circuit as: "0L" in Continuity mode). If the meter detects a short circuit it then displays resistance, generally with a decimal point preceding the number of ohms and the meter may also produce a beep sound.

 

You can use the lowest resistance mode scale (on your meter the lowest is the 200 ohms scale) to test for continuity too, if you'd rather, it's the same test as Diode/Continuity mode but without a beep feature. But always report the mode setting you chose to test with along with the measurement (including the decimal point if one is displayed), so we don't have to guess about the resistance scale you're using.

 

On another note.... I am using the wiring diagram that I posted earlier... and I just noticed that the Grey wire is shown joined to the battery positive wire for the taillights on that wiring diagram. So the wiring diagram is in error, it might be useless to us?

 

I see that the Grey wire connects to the 4wd control unit according to the diagram so you should unplug that as well, before testing for shorted wires again.

 


Sorry about that.  I guess specifics would help when diagnosing an electrical issue!

 

Meter was set to the diode/continuity setting AKATV referenced above. 
 

Meter shows 1 with probes apart.  With probes together I get a 000 and a beep.  
 

With probes on green/red wire and grey wire where the meter plugs into the main harness (plug on the main harness side) I get 015, and moving them around I did get a beep or two, but I couldn’t tell if I inadvertently touched my leads together to get a beep as the only consistent reading I got was the 015.

 

No decimal in that figure, but when checking diodes they all read 520-535.  Isn’t that a measure of resistance?  If so, wouldn’t 015 be almost no resistance, or pretty close to perfect continuity?

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