1988 trx300 fw starting problems - Honda TRX Forum
 
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post #1 of 5 Old 06-05-2019, 12:53 PM Thread Starter
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1988 trx300 fw starting problems

Hello , new here , first post . Figured id introduce myself and post my problem on the same thread . I have a 1988 fourtrax 300fw , mostly restored that I mainly use for hunting . The starting system has been working flawless for years and then after deer season I forgot to trickle charge the battery and didn't notice it for almost a year when hunting season rolled around . Of course the battery was weak , only clicked a few times and then nothing . I had a car battery on charge and hooked it up and it turned over a few times and then nothing . So now I charged the battery and when I hit the button , nothing and I figured something may have gotten fried hooking it up to a car battery . The starter was brand new , only a year old as well as the battery was new . Tested the voltage of the battery and it reads 12.6 . The switch was really old and falling apart so I bought a new switch assembly and when I opened the box on front of the bike the main plug was unplugged and filthy so I cleaned them and installed the new switch , nothing ( headlights not plugged in cuz the plastic is off ) . Maybe the solenoid is bad , I had a new one as a back up and installed it and checked the fuses with my multi meter and the fuses were fine but still won't even click when I hit the starter button . I got out my solenoid jumper button and when I hit the trigger the bike starts so the starter is good . I checked the little diode that apparently controls the neutral safety switch / light and it was packed full of mud . When I unplugged it the light on the dash went out , cleaned it and checked polarity and no reading but when I reinstalled it the light came back on . not sure how the diode works but I have a new one on the way hoping that is what is keeping it from turning over . When I installed the solenoid I used the multi meter and grounded the black to the battery ground and the red to the yellow/red wire and when I hit the start button it jumps up in voltage and when I test the green wire it does the same , so it seems to be getting voltage sent to solenoid , so why isn't it at least clicking ? . Going back to the front to the starter switch plug , I see both the yellow/red and green wire and a brown wire (?) , what is the brown wire for ? Also when I opened the front box and the plug was unplugged , there was a black wire unplugged also , I plugged everything back in . new switch , solenoid , starter , battery , fuses are good , seems to be getting voltage to the solenoid and it still won't turn over . This has me really confused and scratching my head . Anyone have any ideas on this ? I can start the bike fine with the kickstart and it runs great but who really wants to do that , lol ?
I also just redone my whole front brake system , with new calipers and shoes and controls . I have them adjusted all the way out but have to press really hard to get it to stop with the front breaks , is this normal or do I need new drums ? They were pretty rusted and I soaked them in vinegar and scrubbed them with soapy water and scotchbrite , they cleaned up real well and aren't pitted , maybe just too wore down ? All the bike I have owned in the last 25 years have grabbed a lot more than these are grabbing

Any advice would be appreciated , thanks
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post #2 of 5 Old 06-05-2019, 02:40 PM
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Welcome to the forum.

That was a long post - let me try to help you.

First, the wiring questions - main (key) switch; has 4 wires, red black pink and pink/white - when the switch is turned on the red wire is connected to the black wire and the pink is connected to the pink/wht - fuses; two fuses, one for the red wire and one in the pink/wht wire - the pink and pink/white wire have nothing to do with the starter system - the red wire is connected to the black wire when the key switch is turned on, the black wire is 12v + throughout the wiring harness with the switch on.

A diode flows current in one direction only. If you check it with a multimeter, you should get a reading with the meter leads connected one way but not the other way. The diode is inline with the neutral switch, the solenoid grounds through the neutral switch - the black wire goes to the starter button, when the button is pressed, the yel/red wire at the solenoid has 12v +, current flows neg to pos (a lot of people don't believe this, but it's true), current flows from the battery neg, through the frame and wiring harness green wire, through the neutral switch, via the light green wire with the red stripe to and through the diode; at this point the current splits, part goes to the neutral light and part goes to the solenoid via the green/red wire, through the neutral light to the black wire and through the solenoid to the yel/red wire to the starter button, when the button is pressed it connects the yel/red wire to the black wire completing the circuit. Having a neutral light is good. The diode was installed to prevent the starter motor from spinning in reverse. If the battery was installed reverse polarity, the diode prevented the neutral from illuminating and the solenoid would not close. If the diode shorts out, the neutral light will come on and the starter will spin regardless how the battery is installed. If the diode opens (like a fuse) the neutral light will not come on and the starter will not run.

Since the solenoid grounds through the neutral switch, a faulty switch can provide an adequate ground for the neutral light, but not for the solenoid. Sometimes a faulty neutral switch will light the neutral light, but the light will go out when the start button is pressed. A simple test is to unplug the wire from the neutral switch and jump the wire to ground. The neutral light should come on and if the starter works, then the neutral switch is faulty.

The brown wire is 12v + when the light switch is turned on - goes from the light on/off switch directly to the taillight and nowhere else - there is a brown wire with a red stripe that goes from the alarm unit to the oil temperature light - it is the ground wire for the temp light - it is connected to the green wire if the oil temp sensor closes.

Get this taken care of and I'll get back with you about the brakes when I have more time - I'm usually only on the forum in the morning.
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post #3 of 5 Old 06-05-2019, 11:35 PM Thread Starter
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Thanks for the reply . I bought a repair manual to help me with the test you recommended . I did test on everything today and it has got to be the diode keeping it from cranking , its the only thing that tested bad , it has no polarity in either direction . I tested the solenoid , neutral safety switch , reverse switch , made sure there was power going to the solenoid when button was pushed and it all checked out good and the battery is still charged good . Guess i'll find out when the new diode gets here next week , hard to find one in the states and not having to wait for over a month and half to receive it .
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post #4 of 5 Old 06-06-2019, 12:04 AM
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I have one of those diodes on hand - they have been used on 1977 CB500, 2017 TRX250X, and about 100 other models of street, dirt and ATV's

You can test the diode theory with a paper clip, a fuse or a radio shack diode. If you jump the diode with a piece of wire, every thing should work, but it would just be for testing - if the diode has no continuity in either direction, it needs to be replaced - that diode was only used on the 88 300FW, but it was also used on several years of TRX400EX's

Here's a list of all the models of Honda that used that same diode:

1977 CB550K A - LEFT SIDE COVER / ELECTRIC PLATE
1977 CB750F A - WIRE HARNESS / HORN
1977 CB750K A - WIRE HARNESS / IGNITION COIL
1977 XL75 A - WIRE HARNESS / IGNITION COIL / BATTERY
1978 CB550K A - LEFT SIDE COVER / ELECTRIC PLATE
1978 CB750F A - WIRE HARNESS / HORN
1978 CB750K A - WIRE HARNESS / IGNITION COIL
1978 XL75 A - WIRE HARNESS / IGNITION COIL / BATTERY
1979 XL75 A - WIRE HARNESS / IGNITION COIL / BATTERY
1980 CT110 A - WIRE HARNESS / IGNITION COIL
1981 CT110 A - WIRE HARNESS / IGNITION COIL
1981 XL80S A - WIRE HARNESS / IGNITION COIL / BATTERY
1982 CB450SC A - WIRE HARNESS / IGNITION COIL / C.D.I. UNIT
1982 CM250C A - WIRE HARNESS / IGNITION COIL
1982 XL80S A - WIRE HARNESS / IGNITION COIL / BATTERY
1983 CB450SC A - WIRE HARNESS / IGNITION COIL / C.D.I. UNIT
1983 CB650SC A - WIRE HARNESS / IGNITION COIL / RECTIFIER
1983 CM250C A - WIRE HARNESS / IGNITION COIL
1983 CM250C AC - WIRE HARNESS / IGNITION COIL
1983 VF1100C A - WIRE HARNESS / IGNITION COIL
1983 VF750F A - WIRE HARNESS / IGNITION COIL
1983 VT500C A - WIRE HARNESS
1983 XL80S A - WIRE HARNESS / IGNITION COIL / BATTERY
1984 GL1200 A - WIRE HARNESS
1984 GL1200 AC - WIRE HARNESS
1984 VF500C A - WIRE HARNESS
1984 VF500C AC - WIRE HARNESS
1984 VF700S A - WIRE HARNESS / ELECTRIC PARTS
1984 VF700S AC - WIRE HARNESS / ELECTRIC PARTS
1984 XL80S A - WIRE HARNESS / IGNITION COIL / BATTERY
1985 CB650SC A - WIRE HARNESS / IGNITION COIL / RECTIFIER
1985 CB650SC AC - WIRE HARNESS / IGNITION COIL / RECTIFIER
1985 CB700SC A - WIRE HARNESS / IGNITION COIL
1985 VF500C A - WIRE HARNESS
1985 VF500C AC - WIRE HARNESS
1985 VF500F A - WIRE HARNESS / IGNITION COIL
1985 VF500F AC - WIRE HARNESS / IGNITION COIL
1985 VF700F A - WIRE HARNESS / IGNITION COIL
1985 VF700F AC - WIRE HARNESS / IGNITION COIL
1985 VF700S A - WIRE HARNESS / ELECTRIC PARTS
1985 VF700S AC - WIRE HARNESS / ELECTRIC PARTS
1985 XL80S A - WIRE HARNESS / IGNITION COIL / BATTERY
1985 XL80S AC - WIRE HARNESS / IGNITION COIL / BATTERY
1986 ATC250ES A - WIRE HARNESS
1986 ATC250SX A - WIRE HARNESS / BATTERY
1986 CB450SC A - WIRE HARNESS / IGNITION COIL / C.D.I. UNIT
1986 CB450SC AC - WIRE HARNESS / IGNITION COIL / C.D.I. UNIT
1986 CMX250C A - WIRE HARNESS
1986 CMX250C AC - WIRE HARNESS
1986 CMX250CD A - WIRE HARNESS
1986 CMX250CD AC - WIRE HARNESS
1986 CMX450C A - WIRE HARNESS
1986 CMX450C AC - WIRE HARNESS
1986 TRX250 A - WIRE HARNESS
1987 ATC250ES A - WIRE HARNESS
1987 CBR600F AC - WIRE HARNESS
1987 CMX250C A - WIRE HARNESS
1987 CMX250C AC - WIRE HARNESS
1987 TRX250 A - WIRE HARNESS
1988 CBR600F AC - WIRE HARNESS
1989 CBR600F A - WIRE HARNESS
1989 CBR600F AC - WIRE HARNESS
1989 GL1500 A - WIRE HARNESS EXCEPT
1989 GL1500 AC - WIRE HARNESS EXCEPT
1989 PC800 A - WIRE HARNESS
1989 PC800 AC - WIRE HARNESS
1989 TRX300 A - WIRE HARNESS
1989 VT600C A - WIRE HARNESS
1989 XL600V AC - WIRE HARNESS
1990 TRX300 A - WIRE HARNESS
1990 TRX300FW A - WIRE HARNESS
1990 XL600V A - WIRE HARNESS
1991 CB250 A - WIRE HARNESS
1991 CB250 AC - WIRE HARNESS
1991 TRX300 A - WIRE HARNESS
1991 TRX300 AN - WIRE HARNESS
1991 TRX300FW A - WIRE HARNESS
1991 TRX300FW AN - WIRE HARNESS
1992 CB250 A - WIRE HARNESS
1992 CB250 AC - WIRE HARNESS
1992 TRX300 AN - WIRE HARNESS
1992 TRX300FW A - WIRE HARNESS
1992 TRX300FW AN - WIRE HARNESS
1992 VT1100C AC - WIRE HARNESS
1993 CB250 A - WIRE HARNESS
1993 CB250 AC - WIRE HARNESS
1993 TRX300 A - WIRE HARNESS
1993 TRX300 AN - WIRE HARNESS
1993 TRX300FW AN - WIRE HARNESS
1993 VT1100C AC - WIRE HARNESS
1994 CB250 A - WIRE HARNESS
1994 CB250 AC - WIRE HARNESS
1994 TRX300 A - WIRE HARNESS
1994 TRX300 AN - WIRE HARNESS
1995 CB250 A - WIRE HARNESS
1995 CB250 AC - WIRE HARNESS
1995 TRX300 AN - WIRE HARNESS
1995 TRX300FW A - WIRE HARNESS
1995 TRX400FW A - WIRE HARNESS
1995 TRX400FW AN - WIRE HARNESS
1996 CB250 A - WIRE HARNESS
1996 CB250 AC - WIRE HARNESS
1996 TRX300 AN - WIRE HARNESS
1996 TRX300FW A - WIRE HARNESS
1996 TRX300FW AN - WIRE HARNESS
1996 TRX400FW A - WIRE HARNESS
1996 TRX400FW AN - WIRE HARNESS
1997 CB250 A - WIRE HARNESS
1997 CB250 AC - WIRE HARNESS
1997 TRX250 A - WIRE HARNESS
1997 TRX250 AC - WIRE HARNESS
1997 TRX300 A - WIRE HARNESS
1997 TRX300 AN - WIRE HARNESS
1997 TRX300FW A - WIRE HARNESS
1997 TRX300FW AN - WIRE HARNESS
1997 TRX400FW A - WIRE HARNESS
1998 TRX250 A - WIRE HARNESS
1998 TRX250 AC - WIRE HARNESS
1998 TRX300 A - WIRE HARNESS
1998 TRX300 AC - WIRE HARNESS
1998 TRX300FW A - WIRE HARNESS
1998 TRX300FW AC - WIRE HARNESS
1998 TRX400FW A - WIRE HARNESS
1998 TRX400FW AC - WIRE HARNESS
1999 CB250 A - WIRE HARNESS
1999 CMX250C2 AC - WIRE HARNESS
1999 TRX250 A - WIRE HARNESS
1999 TRX300 A - WIRE HARNESS
1999 TRX300 AC - WIRE HARNESS
1999 TRX300FW A - WIRE HARNESS
1999 TRX300FW AC - WIRE HARNESS
1999 TRX400EX A - WIRE HARNESS ('99-'04)
1999 TRX400FW A - WIRE HARNESS
2000 TRX250 A - WIRE HARNESS
2000 TRX300 A - WIRE HARNESS
2000 TRX300 AC - WIRE HARNESS
2000 TRX300FW A - WIRE HARNESS
2000 TRX300FW AC - WIRE HARNESS
2000 TRX400EX A - WIRE HARNESS ('99-'04)
2000 TRX400FW A - WIRE HARNESS
2001 GL1500CF AC - WIRE HARNESS
2001 TRX250 A - WIRE HARNESS
2001 TRX250EX A - WIRE HARNESS ('01-'05)
2001 TRX400EX A - WIRE HARNESS ('99-'04)
2001 TRX400FW A - WIRE HARNESS
2001 TRX500FA A - WIRE HARNESS (TRX500FA'01-'04/FGA'04)
2001 XR650L A - WIRE HARNESS
2001 XR650L AC - WIRE HARNESS
2002 TRX250EX A - WIRE HARNESS ('01-'05)
2002 TRX250TE A - WIRE HARNESS (TE)
2002 TRX250TM A - WIRE HARNESS (TM)
2002 TRX400EX A - WIRE HARNESS ('99-'04)
2002 TRX500FA A - WIRE HARNESS (TRX500FA'01-'04/FGA'04)
2002 XR650L A - WIRE HARNESS
2002 XR650L AC - WIRE HARNESS
2003 CMX250C A - WIRE HARNESS
2003 CMX250C AC - WIRE HARNESS
2003 TRX250EX A - WIRE HARNESS ('01-'05)
2003 TRX250TE A - WIRE HARNESS (TE)
2003 TRX250TM A - WIRE HARNESS (TM)
2003 TRX400EX A - WIRE HARNESS ('99-'04)
2003 TRX500FA A - WIRE HARNESS (TRX500FA'01-'04/FGA'04)
2003 XR650L A - WIRE HARNESS
2003 XR650L AC - WIRE HARNESS
2004 CMX250C A - WIRE HARNESS
2004 CMX250C AC - WIRE HARNESS
2004 NRX1800DA A - WIRE HARNESS
2004 NRX1800DA AC - WIRE HARNESS
2004 NRX1800DB A - WIRE HARNESS
2004 NRX1800DB AC - WIRE HARNESS
2004 NRX1800EA A - WIRE HARNESS
2004 NRX1800EA AC - WIRE HARNESS
2004 NRX1800EB A - WIRE HARNESS
2004 NRX1800EB AC - WIRE HARNESS
2004 TRX250EX A - WIRE HARNESS ('01-'05)
2004 TRX250TE A - WIRE HARNESS (TE)
2004 TRX250TM A - WIRE HARNESS (TM)
2004 TRX400EX A - WIRE HARNESS ('99-'04)
2004 TRX500FA A - WIRE HARNESS (TRX500FA'01-'04/FGA'04)
2004 TRX500FGA A - WIRE HARNESS (TRX500FA'01-'04/FGA'04)
2004 XR650L A - WIRE HARNESS
2004 XR650L A/A - WIRE HARNESS
2004 XR650L A/B - WIRE HARNESS
2004 XR650L AC - WIRE HARNESS
2004 XR650L AC/A - WIRE HARNESS
2004 XR650L AC/B - WIRE HARNESS
2005 CMX250C A - WIRE HARNESS
2005 CMX250C AC - WIRE HARNESS
2005 NRX1800DA A - WIRE HARNESS
2005 NRX1800DA AC - WIRE HARNESS
2005 NRX1800DB A - WIRE HARNESS
2005 NRX1800DB AC - WIRE HARNESS
2005 NRX1800EA A - WIRE HARNESS
2005 NRX1800EA AC - WIRE HARNESS
2005 NRX1800EB A - WIRE HARNESS
2005 NRX1800EB AC - WIRE HARNESS
2005 TRX250EX A - WIRE HARNESS ('01-'05)
2005 TRX250TE A - WIRE HARNESS (TE)
2005 TRX250TM A - WIRE HARNESS (TM)
2005 TRX400EX A - WIRE HARNESS ('05-'06)
2005 XR650L A - WIRE HARNESS
2005 XR650L A/A - WIRE HARNESS
2005 XR650L AC - WIRE HARNESS
2005 XR650L AC/A - WIRE HARNESS
2006 CMX250C A - WIRE HARNESS
2006 CMX250C AC - WIRE HARNESS
2006 TRX250EX A - WIRE HARNESS ('06-'07)
2006 TRX250TE A - WIRE HARNESS (TRX250TE)
2006 TRX250TM A - WIRE HARNESS (TRX250TM)
2006 TRX400EX A - WIRE HARNESS ('05-'06)
2006 XR650L A - WIRE HARNESS
2006 XR650L AC - WIRE HARNESS
2007 CMX250C A - WIRE HARNESS
2007 CMX250C AC - WIRE HARNESS
2007 TRX250EX A - WIRE HARNESS ('06-'07)
2007 TRX250TE A - WIRE HARNESS (TRX250TE)
2007 TRX250TM A - WIRE HARNESS (TRX250TM)
2007 TRX400EX A - WIRE HARNESS
2007 XR650L A - WIRE HARNESS
2007 XR650L AC - WIRE HARNESS
2008 CMX250C A - WIRE HARNESS
2008 CMX250C AC - WIRE HARNESS
2008 TRX250EX A - WIRE HARNESS ('08)
2008 TRX250TE A - WIRE HARNESS (TRX250TE)
2008 TRX250TM A - WIRE HARNESS (TRX250TM)
2008 TRX400EX A - WIRE HARNESS
2008 XR650L A - WIRE HARNESS
2008 XR650L AC - WIRE HARNESS
2009 CMX250C A - WIRE HARNESS
2009 CMX250C AC - WIRE HARNESS
2009 TRX250TE A - WIRE HARNESS (TRX250TE)
2009 TRX250TM A - WIRE HARNESS (TRX250TM)
2009 TRX400X A - WIRE HARNESS
2009 XR650L A - WIRE HARNESS
2011 TRX250TE A - WIRE HARNESS (TRX250TE)
2011 TRX250TM A - WIRE HARNESS (TRX250TM)
2012 CMX250C A - WIRE HARNESS
2012 CMX250C AC - WIRE HARNESS
2012 TRX250TE A - WIRE HARNESS (TRX250TE)
2012 TRX250TM A - WIRE HARNESS (TRX250TM)
2012 TRX400X A - WIRE HARNESS
2012 XR650L A - WIRE HARNESS
2012 XR650L AC - WIRE HARNESS
2013 TRX250TE AC - WIRE HARNESS (TRX250TE)
2013 TRX250TM AC - WIRE HARNESS (TRX250TM)
2013 TRX400X AC - WIRE HARNESS
2016 TRX250TM AC - WIRE HARNESS (1)
2017 TRX250TM AC - WIRE HARNESS (1)
2017 TRX250X 3AC - WIRE HARNESS
2017 TRX250X AC - WIRE HARNESS
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post #5 of 5 Old 06-06-2019, 12:50 AM Thread Starter
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I tried jumping the diode wires the other day and it didn't work , but I went down to try again and it still didn't work . I got to thinking about the way I had to install the solenoid the other day . the plugs were both male ends so I cut the new one off and spliced it into the old plug wires . When I tested it I tested the starter switch side but not after the splice . the yellow / red wire tested ok but the green didn't so I cut it and just twisted it together and she fired right up . I had a feeling it was a ground issue , it almost always is lol . I pulled the jumper wire out of the diode fitting and cleaned it again and put the diode back in and it cranks just fine even though the test shows the diode is bad . Guessing when I put the car battery on the solenoid before it fried the solenoid , and when I installed a new one it wasn't getting a ground anymore from the diode from all the mud in the plug all along . Thanks for the help on the electrical stuff guys
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