Plowing snow the other day when suddenly I lost reverse. Has forward in all four gears but wont go backwards. Any one have any ideas ?
Have never worked on one but, might be helpful to mention if it is electric directional shift or what. Do you have any schematics to post on it. Might need to check pressures for the reverse clutch, but might need a manual to figure out more. Maybe someone else who has worked on will chime in. Simon C
It is electrical directional shift. I do not have a service manual or electrical schematic.
You will have a lever that sends power to go to solenoids. You could figure out possibly which wire coming out of harness from steering column is power for reverse. Simon C
Just checked shift indicator in dash cluster. When park brake is on F lights up in forward, N lights up when in neutral and R lights up when in reverse. When park brake is off F lights up in forward, N lights up in neutral, But when you put lever in reverse N lights up and blinks.
Maybe take that shift lever apart if it does come apart, and maybe some contacts can be cleaned up. Have never seen the inside of one, but you can see what you find. Maybe post a picture. Simon C
Anyone have a picture of where the reverse and forward solenoids are at ?
They would probably be on top of the transmission, unless they are inside under a cover. That's my guess. Simon C
What type of transmission is fitted? ZF 4WG150? Or 180? Type plate somewhere at bottom of housing. Picture of control valve might help, too.
Do you have no reverse in 1st 2&3 gear?
yes. I took the shift lever apart today and figured out which wire did what. Then i ohmed the wires out and the shift lever is working properly. Then i checked the wires in the cab harness that go to forward and reverse and they ohmed out good. but then i got to thinking that they would look the same with a good solenoid or a short. I have to find the shift solenoid and check that.
OHM testing the wires out is a good thing to know which wire goes to which solenoid, but will not tell you if the wire is strong enough to carry the current, because if there is one strand left in a wire it will OHM test perfect from one end to another. At the shifter if you figure out which wire is reverse, then if it has a plug to disconnect it, then at the other end where the solenoids are, you should be able to figure out and disconnect the Reverse Solenoid. You could try swapping out the forward solenoid with reverse and the problem should travel to forward. Often at the solenoids , if they are ouside not internal there is corrosion on the coils which can solve the problem. Simon C
I have a few manuals of some ZF transmissions. So brand and type would be fine. Could share in PN or via "wetransfer" or so with mail address.
If you do not have all ranges in reverse, then it looks like one solenoid the m1 the solenoids are on upper left of trans when view from center pivot area. you will; find a valve cover and solenoids under there, first disconnect harness there and check #2 wire in it I believe it is green for power then in reverse and power on check for 12+volts power and #7 wire LOOKS to be ground BLACK WIRE BEFOR GeTTING IN THE SOLENOIDS
M1 is responsible for reverse
I believe 721c has a 6th solenoids m6 with auto shift
Steve, right, possibly the 721C got 6 solenoids. However M6 has nothing to do with pressure distribution to clutches. M6 is meant to manage clutch fast filling, located on top of righthand cover. Opposite side of M1-M5.
ONE THING TO TRY I HAVE HAD 821C THE CITY PULED IT BACK TO YARD AND TURNED OF MASTER SWITCH AND THEN I GOT THERE turned back on work normally. THERE IS AND CONTROOLLER BEHAIND THE SEAT AND THAT CAN GIVE PREOBLEMS.