case 621b

[clay digger]

Are you sure you have trans pressure? A friend had a Volvo L120 that had the same symptoms. It would run normally for a few minutes and then just stop, no action in any gears. We could hear the charge pump whine when it stopped. It turned out it was a plugged suction screen.

 

[Deerescaper]

721b electrical issues

Hello all and thanks for your help. We did find a shorted wire in the loader joystick control for the 1-2 kickdown. That solved the fuse problem. About 4 hours later had another solenoid go out. At least this time it was one that hadn't been replaced since I've had the unit. Took all solenoids out and cleaned the screens on them of small filings and other debris that had at one time escaped the filter. Hope this helps as Case boys suggested to have alternator tested for possible power spiking that could do this. I don't know but these solenoids are not cheap ($408). If anyone has a cheaper source let me know as I would keep a couple on hand for the future. Loader has 7600 hours on it so I don't know if that's the lifetime for solenoids and it's just my turn to do the replacing or what. Sure was easier in the old days when the controls went direct to the tranny or valve body.

 

[quackattak]

Glad you got your fuse problem solved. The A-model case loaders don't use a computer for the trans, still the ZF trans. We have 1 with over 30,000hrs and another with over 25,000hrs, I have never had solenoid problems with those 2, no trans electrical problems at all. The b's are much more trouble, for the price of those solenoids I would pull the harness apart coming out of the trans and trace the ground wire down. If your ground wire is open there is no control of the voltage and say goodby to your delicate $400.00 solenoids. Also check your chassis ground cables and battery cables, good luck.

 

[mljohn]

what i have done in the past is to put a fusestat or a resetable fuse in place of the one that is blowing.

then i unplug the selenoids one at a time until the load on the fuse goes away.

if it does not go away then the problem is in the harness

hope this helps

 

[superdutyII]

I am just getting back to work on my loader. It still will not move I have replaced trans computer, and took every ground wire off and cleaned contacts and inspected them. I went back and retested solenoids and the second from top would not ohm out I mean nothing the rest of them where from 95 to 105. I bought new solenoid and installed it but loader still will not move. rechecked new solenoids and it ohmed out around 96 or 97. I tried listening for the trans controller for clickin 2 or 3 times but it is hard to hear with break pressure buzzer going off. Any ideas on what to check next?

 

[quackattak]

If you pull your instrument panel out and unscrew the wiring harness your buzzerr will shut off. First thing I would do is listen for the computer to click. Just turn key on don't start engine, if its ok, (2 clicks). Then you can move past solenoid and computer problems. Double check your 5amp fuse in the fuse box also.

 

[hdwrecker]

I have a '97 621B, with 5000+ hrs., that i am having a similar intermitent tranmission issue as well. I can jump in it and run it easy or hard for 5 minutes or 5 hours and all of a sudden the trans. defaults to a neutral state. I have replaced all of my grounds and cleaned all of my connectors, they all look good so far, have not actually ohmed any of my solenoids yet. Has anyone found any "common" problems with this issue that seems to pleague the ZFs??? I am planning on, when the fault occurs next time, pulling the "trans cut-out relay" from under the dash to potentially elliminate the possibility of the brake pressure, park brake, and declutch switches from being the intermittent issue. As my service manual shows, these switched features are all powered through that relay and the machine should run and shift with it removed, obviouly I want to duplicate the issue first. Thanks

 

[superdutyII]

The problem with mine ended up being a broke wire at the connector. the best way to explain it is while you are standing on the right side of the machine in front of rear tire there was a 4 wire connector that screwed in on the top of transmission one of those wires had pulled out.

 

[hdwrecker]

Well, in the long process of elimination, I DID actually find two loose and un-soldered wires at the 6-pin round metal connestor at the solenoid valve pack on the right hand side of the top of the transmission. The connector has 5 blue wires and 1 black, which is the solenoid coil's common ground. When I went to unscrew the small connector, it crumbled in my hand, aluminum locking ring. The integrity of the male end of the connector was good so I cut the connector from the main harness and re-soldered all 6 pins with about 4 inches of new wires, I basicly made my own new pig tail. Then I spliced the 6 wires back to the main harness. Since I no longer had the locking ring on the male end, I slid a piece of good heat shrink tubbing over the whole connector and heated it up. The glue held the connector securely and was better than replacing the whole main harness just for the sake of a broken locking ring. My '97 Case 621B now drives and shifts perfectly with no intermitent faults or nuetral-like shifts. I drove it several more days and was happy to deliver it to the customer. Thanks for the support and ideas in the above posts.

 

[William Schuda]

Usually the cpu is good (seems to be rather tough) As mentioned before, check the tcu for clicks, 2 is normal a 3rd is it shutting itself down due to a problem. Check the resistance of all your solonoids (i believe spec is around 100-115 ohms) If any of your solonoids resistances are too high or low the controller will shut itself off. Also check all your grounds. The harnessess get old and the grounds get poor. Check the one from your cab to frame, rh side, and there are some below the instrument pannel. Also check your connectors to your solonoids, ensure they are clean (the connector from the cab to the solonoids)

Does your machine have auto shift??

Check your speed sensor, (one is on the LH side, and if you have auto shift the other will be on the RH side top) Sometimes the wires rott off, or the sensor is bad. spec is 1350 to 1590 ohms. A bad speed sensor will prevent you from having 3rd and 4th

A problem in the declutch will prevent you from having 1st and 2nd. You need power to the controller at the declutch wire (i dont remember the wire number right now)

Where are the speed sensors? Are they on an axle or on the transmission some where? I have auto shift do I have 2 sensors?

 

[alrman]

Here's a pic of the sensor locations - there are two listed - part number 315733A1