IH Truck 2 Speed Issue

[nh8260]

I have a problem with the 2 speed in my IH 1600 Loadstar, it was working at one time and now not so much. If I am in high range everything is good, if I go to low the Amp gauge goes to negative and it blows the fuse. I've had the 2 speed box ( Eaton Brand) rebuilt and rechecked twice, I put a new red button switch in, and today I put a new harness with the plug that the 2 speed switch plugs into at the shifter. Did the same thing (blown fuse) when I went to low side. The only thing left to do that I know of is run new wire all the way back to the rear axle, I have checked the wires from the axle to the shifter and don't see any broke wires or anything grounding out. Anyone on here ever had this problem or know something I'm missing???

Truck has 345 engine and 5+2 tranny.

 

[wore out]

.

 

[used red MN]

Disconnect the wires at the two speed actuator on the axle and see if you still blow the fuse that would tell you if it is the wiring. Just FYI, one wire should go onto one of the motor bolts to provide an adequate ground. Probably have to wiggle the wire around a bit by the axle to mimic the axle moving around. Any clutch or trans work been done recently that could have damaged the wires? Exhaust is always an issue on those old gas burners, check that it hasn’t melted the wires. Those electric two speed actuators are real simple, the double spring loaded fork actuator, worm gear, motor, motion limit switch and that’s about it. Here is a video, I have issues with two things shown in it. He breaks a screw that holds the limit switch in. The two electric studs hold it fine but he should have said what happened. He also says the nut has to come off the lead screws bearing. The bearing and shaft come out together when the bottom round 3 bolt plate comes off. My guess is his had some corrosion that made it stubborn.
Edit 2: I am sure it was covered in the video, having oil to the level of the check plug is also important.
Two speed axle actuator repair

 

[Bob Bancroft]

I have a problem with the 2 speed in my IH 1600 Loadstar, it was working at one time and now not so much. If I am in high range everything is good, if I go to low the Amp gauge goes to negative and it blows the fuse. I've had the 2 speed box ( Eaton Brand) rebuilt and rechecked twice, I put a new red button switch in, and today I put a new harness with the plug that the 2 speed switch plugs into at the shifter. Did the same thing (blown fuse) when I went to low side. The only thing left to do that I know of is run new wire all the way back to the rear axle, I have checked the wires from the axle to the shifter and don't see any broke wires or anything grounding out. Anyone on here ever had this problem or know something I'm missing???

Truck has 345 engine and 5+2 tranny.

With the two speed box removed do you know for sure you can take a bar and shift the axle? The shifter I was most familiar with was the old one with the little check plug on the front which held 10W oil. Then I got the truck I have now which doesn't hold any oil. It has a circuit board inside which I've replaced twice. Which is yours? Or are there even more styles? (Other than air shifted, which I've also had)

 

[used red MN]

With the two speed box removed do you know for sure you can take a bar and shift the axle? The shifter I was most familiar with was the old one with the little check plug on the front which held 10W oil. Then I got the truck I have now which doesn't hold any oil. It has a circuit board inside which I've replaced twice. Which is yours? Or are there even more styles? (Other than air shifted, which I've also had)

I am pretty sure an IH 1600 Loadstar would have the square check plug style. That would be a late 60s early 70s model. Don’t think the circuit board type came out until the 80s.

 

[sms]

With the two speed box removed do you know for sure you can take a bar and shift the axle? The shifter I was most familiar with was the old one with the little check plug on the front which held 10W oil. Then I got the truck I have now which doesn't hold any oil. It has a circuit board inside which I've replaced twice. Which is yours? Or are there even more styles? (Other than air shifted, which I've also had)

That was one possibility I thought of, if the rear shifts hard the fuse would blow.

 

[used red MN]

That was one possibility I thought of, if the rear shifts hard the fuse would blow.

In actuality the motor in proper condition easily over comes the spring that loads up when you shift it. I remember when I was young seeing drivers split shift the transmission changing from hi axle to low axle during the transmission shift. The immediately switch the axle into high while keeping the accelerator down just preparing for the next axle shift. My mechanical mind said “that can’t be to good for it” when in fact it hurts nothing. The spring is just loaded to move the rear end fork when torque pressure is relaxed from the gears.

 

[Bob Bancroft]

In actuality the motor in proper condition easily over comes the spring that loads up when you shift it. I remember when I was young seeing drivers split shift the transmission changing from hi axle to low axle during the transmission shift. The immediately switch the axle into high while keeping the accelerator down just preparing for the next axle shift. My mechanical mind said “that can’t be to good for it” when in fact it hurts nothing. The spring is just loaded to move the rear end fork when torque pressure is relaxed from the gears.

When I regularly drove a truck with two speed axle I found that every autumn I wanted to remove the cover and clean out the heavy gear oil which had seeped into the shifter housing and refill the 10W oil. Then it would work all winter. Likewise with the air shifted one I had. Every autumn take the cover off and clean out the crud which accumulated from the air cylinder. Then it would work all winter.
The only one I have now is an old off road farm beater IH 1724 dump truck. It's the first year of the S series I believe, 1979. It has the dry sump with circuit board. It was not working when I bought it. The first replacement circuit board lasted about a year. I could see when I replaced it where a bad solder joint had failed it. So I didn't really need the next new one I had, but installed it. I re soldered the failed one and put it under the truck seat.

 

[nh8260]

Disconnect the wires at the two speed actuator on the axle and see if you still blow the fuse that would tell you if it is the wiring. Just FYI, one wire should go onto one of the motor bolts to provide an adequate ground. Probably have to wiggle the wire around a bit by the axle to mimic the axle moving around. Any clutch or trans work been done recently that could have damaged the wires? Exhaust is always an issue on those old gas burners, check that it hasn’t melted the wires. Those electric two speed actuators are real simple, the double spring loaded fork actuator, worm gear, motor, motion limit switch and that’s about it. Here is a video, I have issues with two things shown in it. He breaks a screw that holds the limit switch in. The two electric studs hold it fine but he should have said what happened. He also says the nut has to come off the lead screws bearing. The bearing and shaft come out together when the bottom round 3 bolt plate comes off. My guess is his had some corrosion that made it stubborn.
Edit 2: I am sure it was covered in the video, having oil to the level of the check plug is also important.
Two speed axle actuator repair

I removed the wires and the gauge did not move and did not blow the fuse, i'm guessing something is bad with the actuator?? Yes it does have 10W oil in it, I put the 2 wires back on the actuator like it was when I removed it. The wiring harness is attached to the frame and can not get to the exhaust.

 

[nh8260]

Disconnect the wires at the two speed actuator on the axle and see if you still blow the fuse that would tell you if it is the wiring. Just FYI, one wire should go onto one of the motor bolts to provide an adequate ground. Probably have to wiggle the wire around a bit by the axle to mimic the axle moving around. Any clutch or trans work been done recently that could have damaged the wires? Exhaust is always an issue on those old gas burners, check that it hasn’t melted the wires. Those electric two speed actuators are real simple, the double spring loaded fork actuator, worm gear, motor, motion limit switch and that’s about it. Here is a video, I have issues with two things shown in it. He breaks a screw that holds the limit switch in. The two electric studs hold it fine but he should have said what happened. He also says the nut has to come off the lead screws bearing. The bearing and shaft come out together when the bottom round 3 bolt plate comes off. My guess is his had some corrosion that made it stubborn.
Edit 2: I am sure it was covered in the video, having oil to the level of the check plug is also important.
Two speed axle actuator repair

Hey used red, so when I attached the wires back nothing happens, the amp gauge doesn't move, fuse doesn't blow but I also don't hear the 2 speed moving, you could always hear it kinda growl as it was moving but nothing now

 

[used red MN]

Hey used red, so when I attached the wires back nothing happens, the amp gauge doesn't move, fuse doesn't blow but I also don't hear the 2 speed moving, you could always hear it kinda growl as it was moving but nothing now

You need a test light or meter to see if power to the wires where they attach. What were you doing when you had them unhooked?
Did the terminal studs turn any when you were unhooking them?

 

[nh8260]

You need a test light or meter to see if power to the wires where they attach. What were you doing when you had them unhooked?
Did the terminal studs turn any when you were unhooking them?

I did like you said, while they were unhooked I turned the switch on to see if the fuse would blow. I don't think they turned any, if so what would that do?

 

[used red MN]

I did like you said, while they were unhooked I turned the switch on to see if the fuse would blow. I don't think they turned any, if so what would that do?

It could cause the internal switch contacts to lose connection. You say it was rebuilt/repaired twice?
1. Did it work after they fixed it?
2. Does the top of the motor look new like it was replaced?
3. Did you check for power at the terminals now that it isn’t working?
4. What did you have to do to replace the switch plug/harness? Did it include butt connectors, you sure you have them all crimped on properly?

 

[nh8260]

It was rebuilt and after that I have taken it back to the powertrain shop twice, when they put power to the actuator it worked fine. the terminal studs could have moved, do i need to take the front cover off the actuator and see if anything has come loose or not attached???

No it did not work at all
Everything in the box is new including the motor
I used a test light at the actuator but nothing lit up.
Yes i used butt splices on the wires and everything was put back like it was.

 

[used red MN]

Is your fuse making connections to the tabs in the box it slips in? Use a test light to check for power on the metal tabs it slips in on both sides. Also on occasion the fuse filament will not be blown but it loses connection with the end cap, bad fuse. If you have power at the axle and you have a ground wire that works you’ll have to open it up. A bad ground would light your test light between the actuator body and the truck frame. This would normally not blow a fuse, it is not very good for drive train bearings.

 

[hammermill]

i just bought a 1977 loadstar and on the way home it went into neutral like a bad clutch , but when i got home the drivesfats spins but to rear end movement and the wires on the 2 speed are cut ?

 

[2SteveWI]

This is an old post , but I think I can help you. Behind the electric 2 speed unit is 2 nuts holding it onto rear axle. The old style shift motors had posts for 2 wires on back side of unit. to test unit put ground wire anywhere on metal and energize one of the posts with a hot wire. If nothing happens energize the other post. there should be a 2-3 second whirring sound and then shutoff after arm moves. These were replaced in 90's with an electronic shift motor with a plastic front cover. There is a circuit board in there than burns out and could be rebuilt. That has been several years and it may be cheaper to replace whole motor. You should be able to put a plate over where shift motor was bolted to hold lever in either Hi, or Low to get by for a while. Steve.

 

[Fritz Maurer]

Either broken axle or the shift unit is between ranges. Can shift by hand with 2 speed shifter removed.

 

[used red MN]

i just bought a 1977 loadstar and on the way home it went into neutral like a bad clutch , but when i got home the drivesfats spins but to rear end movement and the wires on the 2 speed are cut ?

I would just pull the entire two speed shifter unit off. When you get it off shove the shift end of the shift fork toward the wheel and try turning the drive shaft see if it will engage. The try the opposite trying to push it towards the driveshaft. The two directions are low and high axle, been to long to remember which is which.
If no joy what Fritz said or something went in the differential. If it goes in gear you can do the testing Steve is talking about with the shift unit in a vise and negative of a test battery connected by a jumper cable to the base of the unit and a jumper wire to run power from the positive to the terminals. Might not hurt to throw a 12 volt 20 amp breaker in your jumper wire to kick out if something in the unit is shorted.