Ya I appreciate all of your input.. I definitely have a better understanding of this machine.

good deal
glad you got it repaired

next time you have issues with travel you'll know where to look first ;o)

Just got the truck done today. Had to replace the broken prox switch and had to solder in a new connector. When the old switch got broken it internally broke the connection.. Unit acting normal now... Thanks everyone for all of your info.

every combi i've worked on the prox switches have indicator lights on them around the circumfrence of the back end where the harness plugs into them. They look like orange dots, sometimes you have to look closely at them and maybe even use a mirror to get close to them to see it, but if there is alot of light, the ones that are enclosed in a dark area like underneath the cabin or inside the wheel well mechanism at the front wheel you can usually see.

But if none of them are lighting up you have a problem somewhere, most likely a lost ground or a bad relay. He may want to check the directional switch, they have been known to give problems like this too. Once he sees all the connections on the directional switch he'll understand what i'm saying.

And trev your not wrong about the pressures generated when these wheels/cylinders max out at their endpoints, they do trigger diverter valves and check valves in the system to insure proper hydraulic operation sequence but the sensors control the electrical part of these functions. If they are not working properly theres a 100% chance there will be malfunction of steering/travel.

Sensors at the wheels tell the hydraulic system what position the wheels are in so that the valves that control the travel will divert the fluid properly for the mode and direction the machine is trying to move in. If any one of them stops working you may get movement but the hydraulic system will cross circuits and cause a 'deadhead' scenario and keep the machine from moving correctly. In some cases i've seen it keep the truck from moving at all or when you choose a direction it moves in a different one that selected all because of these sensors.

Thats the fun part about dealing with electrical over hydraulic controls ;o)

have some info for the 4000 need your mail, not seen one for a while, if i remember one load wheel turns then next second wheel then drive and returns the other way round( front wheels must hit against large stopping blolts this prevents rams from fully reaching allowing pressure to activate other wheels) if front wheels are turning ok on demand check the proximity switches on drive wheel they should light up but do fail and still light have a look at the opposite one to the one that is activated, sometimes there is a spare sensor just below the steering wheel in cab all problems i used to have were sensors either broken or slipped in plastic clamp and sensing something else, test with spanner to light up

until you get those prox switches repaired the truck will not operate correctly.

None of the prox switches are illuminated. The truck steers fine in neutral or traveling left or right. So I don't think it's the steer cylinder but at this point I can't rule anything out yet.... The left front outside prox switch is broke... Due to the customers production schedule I'm unable to do anything till Saturday.

Hi mike,
The only experience I have had with the steering on a combi that was exactly like your problem turned out to be a mechanical problem,
And what had happened was the rod end had snapped of the drive wheel steer cylinder, on removing the steer cylinder and taking it for repair and on stripping it down it was found that the piston had screwed of the piston rod inside the cylinder, might you have a similar problem.

If the truck has the carousel option the prox switch will be located at the left front wheel inbetween the other 2 sensors, probably going to be hard to see easily, you will have to rotate the wheel or remove the cover plate to see it(if it has a cover plate installed). On the dash there would be a switch clearly marked with a pict-o-gram showing the wheels in carousel mode.

There is no controller, everything goes through the relays.
If the relays are working properly they should illuminate when turned on, should be orange led indicators back near the connector end of the sensor. The ECM mounted on the engine is for the engine operations ONLY.

One of the most common problems i've found is the sensors get knocked out of adjustment causing issues like this one you have.

The parts book also states there's a prox switch for carousel, where is that? I've found 2 switches on the front left wheel and 2 switches on the steer wheel. Also these switches have to feed into a controller (I assume). Are these prox switches suppose to illuminate? Where is the controller or pfc located? I've found the ecm mounted to the engine and alot of relays under the control panel, but no controller. Thanks Mike

I agree with swoop, Also check Wiring and the Relay switches under the Ign switch and gauges

yes the prox switches are what controls the direction valves when you switch from fwd/rev to traverse travel.
There are prox switches on the rear and also on the outrigger wheels. They all have to signal the system that they are turned and locked in before the travel will change to that direction you select.