Register free!
Search
 
     

The Green Industry's Resource Center


Click for Weather
Reply
 
Thread Tools Display Modes
  #1  
Old 09-03-2007, 03:39 PM
csblunt csblunt is offline
LawnSite Member
 
Join Date: Sep 2007
Location: Howell, MI
Posts: 4
JD GT235 Electrical issues

I have a John Deere GT235 with a Kawasaki FH580V 18HP engine, I’ve been having some weird electrical issues and I’m not sure which component is the culprit.

The issues started yesterday when I was mowing and the PTO disengaged after about 30 minutes. I re-activated it and it turned off again after about a minute, then again after a few seconds.

After turning off the machine to try and identify any issues the mower wouldn’t restart. I was able to jump start the tractor and noticed that the battery light was on. After about 2 minutes I heard a huge POP and noticed that one of the components (relay or something similar) on the Ignition Control Module was dripping a fluid and started smoking (with the resulting “burning electrical” smell.

Not being sure if it was the control module that was the problem, or the outcome of another issue I decided to try some additional diagnosis

1) Had battery tested at NAPA who indicated that it was under-charged however, wasn’t reflecting any bad cells, etc.

2) I re-charged the battery on a battery charger however, wouldn’t start the tractor. Was able to re-jump (so I’m thinking I have a bad battery)

3) Checked across the outer two terminal of the Voltage Regulator and getting 31 V (AC).

4) Checked center terminal of voltage regulator to ground and started at 9.2V and worked up to 12.5 V after about 30 sec but never went above 12.5 V
(DC)

5) Checked the stator leads for continuity to ground and reflecting no continuity.

6) Checked the resistance between two stator pins and getting .1 ohm

7) Checked DC Voltage directly at battery and saw strange results – With lights on and full throttle saw voltage go as high as 17.2V DC at which point control module started smoking again. When lowering the RPM/Throttle voltage went down and module stopped smoking.

I’m really at a lost of which component(s) may be the cause of my issues.

Any suggestions would be appreciated.

Thanks!

Chris
Reply With Quote
  #2  
Old 09-03-2007, 06:31 PM
Bill Kapaun's Avatar
Bill Kapaun Bill Kapaun is offline
LawnSite Senior Member
 
Join Date: Oct 2001
Location: Albany, Orygun
Posts: 760
Starting off-
Probably something was wrong with the charge system and the battery voltage started decreasing. When it got low enough, the PTO started to drop out, due to insufficient voltage. A brief "pause" for the battery to recover a bit and the PTO has enough voltage to engage again, until it draws the battery back down. Each time, the battery has less"power" and the PTO drops out sooner and sooner.....until there;s not enough voltage to engage. At this point, you don't have enough voltage to start either, (actually, you probably didn't have enough to start at some time before this point).

"2) I re-charged the battery on a battery charger however, wouldn’t start the tractor. Was able to re-jump (so I’m thinking I have a bad battery)"
Maybe not charged enough? Charge it more and also try starting with the voltage regulator disconnected. The VR may be shorted and drawing excess current.

"3) Checked across the outer two terminal of the Voltage Regulator and getting 31 V (AC)."
Was this with the regulator disconnected? IF NOT, retest with it disconnected.

"6) Checked the resistance between two stator pins and getting .1 ohm"
Is this subtracting the resistance of the test leads? Leads themselves could be that much.
Could the reading be 0.2 ohm? If you have an analog meter, it gets pretty hard to measure that small of an amount. (0.2 "sounds" a bit more typical) The fact you are getting 31 VAC tends to infer the stator is good, although I don't know the exact Kaw spec. (Briggs can be a min of 28 VAC to a min of 40 VAC, depending on the system)

7) was the regulator hooked up on this test?
Reply With Quote
  #3  
Old 09-03-2007, 08:05 PM
csblunt csblunt is offline
LawnSite Member
 
Join Date: Sep 2007
Location: Howell, MI
Posts: 4
Thanks Bill –

I recharged the battery using a trickle charger and battery was reflecting 12.7V when re-installing into the tractor. With the VR disconnected their wasn’t enough “juice” to turn over the tractor (just hearing a hum and assuming it’s the starter). When I measure voltage across the battery with the key on its reflecting 8.5 volts and then returned back to around 12.5V within about a minute of turning the key back off. Not sure if this is an issue or not as I really don’t know a lot about batteries so figured I’d share the info.

When I checked the voltage across the outer terminals it was with the VR disconnected (the three “bottom” wires; however, the Yellow and Green wires were still connected on the flat side of the VR – so hopefully I did it correctly).

For #6 I retested the resistance and was getting .2 ohms (.1 ohm measurement for the leads themselves). I’m using a sears digital multi-meter.

For #7 where I was getting upwards of 17.5Volts it was with the Voltage Regulator attached.
Reply With Quote
  #4  
Old 09-03-2007, 08:14 PM
fly-4-fun's Avatar
fly-4-fun fly-4-fun is offline
LawnSite Member
 
Join Date: Feb 2006
Location: Charlotte, NC
Posts: 124
At WOT the stator should read a minimum of 34 volts AC at the stator connector. The resistance across the stator leads should be between .24 and .40 ohms and the resistance across each stator lead and ground should be infinite. The voltage regulator should keep the voltage at the battery between 12.2 and 14.7 volts DC at WOT. (Wide open throttle) Since your regulator smokes at this speed, it seems to me that it is the likely problem if the AC voltage is correct at the stator.
__________________
I used to have a handle on life, but it broke !!
Reply With Quote
  #5  
Old 09-03-2007, 10:10 PM
Bill Kapaun's Avatar
Bill Kapaun Bill Kapaun is offline
LawnSite Senior Member
 
Join Date: Oct 2001
Location: Albany, Orygun
Posts: 760
"When I measure voltage across the battery with the key on its reflecting 8.5 volts and then returned back to around 12.5V within about a minute of turning the key back off."
The battery needs charging or is bad, although 8.5V would be plausible when CRANKING. Not if just in the ON position.
The fact it takes a minute to return to 12V indicates something is wrong with the battery.
I'm wondering if the regulator shorted, thus passing AC to the battery, killing it and also "messing up" the ign. module and your wires?
Nominal battery voltage is 12.6V, so obviously an alternator has to put out more than that to charge it.

I would say at a minimum, the Voltage Regulator is bad.
Put the battery on the charger overnight (disconnected) and get it retested. You can't properly test a discharged battery.

I'm thinking the resistance of the stator sounds too low. Possibly it had "some" windings short together. I think I would remove it and at least visually, look for "scorched" areas.
IF the "control module" was smoking, I would suspect it's life is at least shortened???
Have you inspected for melted wires elsewhere in the harness?
Reply With Quote
  #6  
Old 09-05-2007, 01:15 PM
csblunt csblunt is offline
LawnSite Member
 
Join Date: Sep 2007
Location: Howell, MI
Posts: 4
Thanks Bill for the good information - Sounds like I definately have a bad Voltage Regulator. In fact you're theory on how the Battery could have gotten Fried seems to confirms a strange reading I was getting - I "accidently" measured for AC voltage on the battery instead of DC and saw 40V AC at one point (it was only temporary, and I didn't get readings that high later when I was checking the outside terminals of the VR.

It sounds like my best bet at this point at a minimum is to change out the VR and possibly the battery and see what I get from there?

Thanks again for the great insight!

Chris
Reply With Quote
  #7  
Old 09-05-2007, 04:07 PM
Bill Kapaun's Avatar
Bill Kapaun Bill Kapaun is offline
LawnSite Senior Member
 
Join Date: Oct 2001
Location: Albany, Orygun
Posts: 760
I'd still fully charge (off the tractor) & test the battery to confirm its demise.
OTOH, if it's already a few years old, it may have been "fried" beyond recovery.
Reply With Quote
  #8  
Old 09-05-2007, 04:26 PM
Bill Kapaun's Avatar
Bill Kapaun Bill Kapaun is offline
LawnSite Senior Member
 
Join Date: Oct 2001
Location: Albany, Orygun
Posts: 760
Too slow on the trigger to edit the above-
Exercise caution when putting the unit back in service.
After changing the VR, check things out, one at a time.
Start engine and at full throttle check-
1. Battery V, both AC & DC. There should be NO AC!
2. Turn on headlights and check DC.
3. Engage PTO and check DC
Voltage should be 13+ to 14+ DC.
It'll probably drop a "few" 0.1's each time.

Keep fingers crossed re: ignition module At least you now know it's "suspect" in case of future engine running "issues".
Reply With Quote
  #9  
Old 09-05-2007, 11:53 PM
fixer67's Avatar
fixer67 fixer67 is offline
LawnSite Silver Member
 
Join Date: Apr 2004
Location: Tryon NC
Posts: 2,161
Quote:
Originally Posted by Bill Kapaun View Post
Too slow on the trigger to edit the above-
Exercise caution when putting the unit back in service.
After changing the VR, check things out, one at a time.
Start engine and at full throttle check-
1. Battery V, both AC & DC. There should be NO AC!
2. Turn on headlights and check DC.
3. Engage PTO and check DC
Voltage should be 13+ to 14+ DC.
It'll probably drop a "few" 0.1's each time.

Keep fingers crossed re: ignition module At least you now know it's "suspect" in case of future engine running "issues".
If the VR is going bad it could be letting AC though. AC coming out of a VR can spell real problems. Now use a meter that test for TRUE RMS AC VOLTAGE. Some cheap DMM can not tell the difference between the two.
__________________
"DEFECTIVE OWNER/OPERATOR NOT COVERED UNDER WARRANTY"
Reply With Quote
  #10  
Old 09-06-2007, 01:41 AM
Bill Kapaun's Avatar
Bill Kapaun Bill Kapaun is offline
LawnSite Senior Member
 
Join Date: Oct 2001
Location: Albany, Orygun
Posts: 760
Why would you need "TRUE RMS AC VOLTAGE"?
Seems to me, that anything resembling an AC Voltage is verboten!.
Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump





Powered by vBulletin® Version 3.8.6
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Copyright ©1998 - 2012, LawnSite.com™ - Moose River Media
All times are GMT -4. The time now is 12:31 AM.

Page generated in 0.11681 seconds with 9 queries