LT40HDD clutch/throttle problems- SOLVED!

CalebL · February 12, 2012, 10:36:02 PM

Went to do a job yesterday and got set up to start sawing and put a new blade on to start. When I engaged the clutch the engine didn't throttle up. I hate when this stuff happens when the customer is around and it was 18 degrees and 20 mph wind that morning to add insult to injury. Anyway I cleaned up and readjusted the throttle sensor, tried engaging the clutch again and nothing. I went to get my meter to test the solenoid and of course the battery was dead. Anyway, I told the customer it was probably the solenoid and I wouldn't be able to saw and he seemed pretty relieved as he didn't want to be out in that weather anyway.

I was pretty sure it was the solenoid so I went onto Woodmizer's website to order another thinking its going to be $30 or so. Wrong, $105. So I get to thinking, maybe I should make sure it's really the solenoid before I order a new one. So, by this time it's dark. Get a new battery and test the solenoid out. It's got continuity so it's good. So it has to be the throttle sensor right? My question is, I should be able to start it up tomorrow (if we don't get the ton of snow and ice they are calling for) and check for voltage going to the solenoid. If no voltage it should be the sensor. I should also be able to bypass the sensor and get voltage to the solenoid, right? If that doesn't work, I'm looking for a short somewhere. Anything else it could be?

Magicman · February 13, 2012, 08:12:45 AM

I'm not familiar with your throttle arrangement, but back to basics, before you can get voltage "from" the sensor, you have to get it "to" the sensor. Be sure that you do not have a breaker kicked.

Magic Smoke · February 13, 2012, 09:18:11 AM

CalebL
There is a small breaker under the cover on the RH side (alternator side) of the engine where you'll see a bunch of wires going up under, make sure it is not tripped if you find no voltage getting to the throttle solenoid, if the breaker was tripped, reset it and make sure the throttle linkage is adjusted properly (if the throttle linkage doesn't allow the solenoid to pull all the way in, it will pop the breaker). If the breaker is okay, check the engage sensor on the up/down gear box, if no voltage is getting to the sensor, check the breaker feeding sensor (breaker location depends on exact model), if sensor has voltage, put a screwdriver (or something metal) in front of the sensor target area, if the throttle works with the screwdriver in front of it, adjust the sensor, if not, replace the sensor (you can hook the two wires together to bypass temporarily).
Hope this helps.

CalebL · February 13, 2012, 12:34:57 PM

Quote from: Magicman on February 13, 2012, 08:12:45 AM
I'm not familiar with your throttle arrangement, but back to basics, before you can get voltage "from" the sensor, you have to get it "to" the sensor. Be sure that you do not have a breaker kicked.

Yes, it was already dark last night and I didn't want to start it up and trace it out in the dark. I am planning on checking it with my meter when I get a chance. The breaker though I didn't know about. I will check that out first. Thanks Magic!

CalebL · February 13, 2012, 12:47:31 PM

Quote from: Magic Smoke on February 13, 2012, 09:18:11 AM
CalebL
There is a small breaker under the cover on the RH side (alternator side) of the engine where you'll see a bunch of wires going up under, make sure it is not tripped if you find no voltage getting to the throttle solenoid, if the breaker was tripped, reset it and make sure the throttle linkage is adjusted properly (if the throttle linkage doesn't allow the solenoid to pull all the way in, it will pop the breaker). If the breaker is okay, check the engage sensor on the up/down gear box, if no voltage is getting to the sensor, check the breaker feeding sensor (breaker location depends on exact model), if sensor has voltage, put a screwdriver (or something metal) in front of the sensor target area, if the throttle works with the screwdriver in front of it, adjust the sensor, if not, replace the sensor (you can hook the two wires together to bypass temporarily).
Hope this helps.

If the breaker isn't tripped and I am getting power to the sensor, I am going to bypass the sensor to see if that engages the solenoid.

I had noticed that on the last saw job I did before this one, every once in a while I would engage the clutch and it wouldn't throttle up. Once it did that I would re-engage the clutch it would start working again. I just figured it was dirty and would clean it off when I changed blades. However, this time it wouldn't work from the beginning. Being that it is a magnetic pickup, I don't see how it could be the sensor but I guess anything is possible.

Magic Smoke · February 13, 2012, 01:30:53 PM

Sometimes the sensor gets a little weak and can have trouble sensing the linkage that passes in front of it when engaging the clutch. If it works by sticking a screwdriver in front of it, just adjust it a little closer to the linkage. If a screwdriver doesn't make it work, but bypassing does, replace the sensor.

CalebL · February 13, 2012, 07:26:27 PM

Well I was able to find the breakers, I think. This was the only thing I could find that could have been a breaker. Am I in the right place? This is on a 2005 LT40HDD34 Cat. I didn't get home until dark and it's still pretty nasty outside so I won't be able to start it up until tomorrow.

customsawyer · February 13, 2012, 08:03:10 PM

You are in the right place. The breaker is in the middle on the bottom of that little black box.

CalebL · February 13, 2012, 09:22:32 PM

Quote from: customsawyer on February 13, 2012, 08:03:10 PM
You are in the right place. The breaker is in the middle on the bottom of that little black box.

It doesn't look tripped, does it? I assume the breaker is the white part. Do they pop out when tripped.

Magicman · February 13, 2012, 09:31:45 PM

Did you check for voltage at the sensor?

CalebL · February 13, 2012, 09:58:20 PM

Quote from: Magicman on February 13, 2012, 09:31:45 PM
Did you check for voltage at the sensor?

Not yet. Its been snowing/sleeting/raining and I didnt get home until dark. I should be able to check it out tomorrow.

MartyParsons · February 13, 2012, 10:10:30 PM

Hello,
From left to right on the picture. Two solenoids on left ( green on top) one is for throttle the other is for starter. Should be L11 and L12 in your wiring diagram in the manual. The circuit breaker CB8 is in the middle, but you will not have the start relay working if it tripped. The relay R1 to the far right is for glow plugs.
You can check the CB8 with a 12v test light ignition switch on. Throttle sensor is bolted to the up and down gear box, you can put a long screw driver or anything metal against it and listen for the solenoid to snap closed.
Hope this helps.
Marty

customsawyer · February 14, 2012, 04:26:35 AM

The small little black box in the middle of your pic. that has the wire attached with a small nut is the breaker. If feel the bottom of the breaker there is a small tab that if it is tripped you just have to push it in and you will be running. If it is not tripped then you will need to start the voltage search.

CalebL · February 14, 2012, 08:03:33 PM

Well, I traced everything out and it didn't make any sense to me. The solenoid had continuity, the throttle sensor was good, and I had 12 volt power to the sensor but it wasn't making it back to the solenoid. I did my best to figure it out but a broke down and called Woodmizer and had them help me figure it out.

I talked to Mike (I forgot to ask his last name) in electrical and he had me try a bunch of different things. Switch relays, test this, test that, finally an hour a 10 minutes later we narrowed it down to the wire going from the sensor to the throttle relay. I had power on one end of the wire but not on the other. I had some spare wire so I ran a new one to see if that would work. It did. Apparently, there is a resistor on the wire hidden in the wire mesh protector. According to Mike, he has never heard of one these burning out. Well, leave it to me to be the one it happens to.

The good news is I didn't have to order a new solenoid or sensor. Mike is sending me a new resistor to splice in the wire and it should be here Thursday. If one of you Woodmizer guys are reading this, please let me know what Mike's last name is, I would like to call back in and thank him. ;D

Magicman · February 14, 2012, 09:36:23 PM

I'm happy to hear that the problem was identified and isolated. Now the technician in me has to ask why? I would have to know how much current (read amps) is in that circuit, and what it is designed to be. Maybe that little "pigtail" was defective and that is good enough. If it was not defective, then something caused more current to flow than it was rated for and the pigtail was cooked.