1987 JCB 3CX Syncro Shuttle Drive Problem

[Slooby]

It's rather infuriating when you spend lots of time and effort only to find that you still have the initial problem; I am no electrical expert so I cannot offer you any advice

Me neither, I know enough to check for continuity with a meter, and follow the wiring, but when it comes to the actual operation and testing for signal etc I start to loose the plot

Does this machine have a transmission, disconnect when the handbrake is applied?

I've no idea, the maintenance manual isn't much help to be hones;, its transmission fault finding guide just talks about checking the the shuttle reverser pump is being driven by the torque converter, which as far as I can tell is all inside the casing, and checking the shuttle valve pressures, which I don't have the equipment to do. It makes no mention of how to check anything electrical or what moves the shuttle valve in the first place!

I would have thought that any transmission disconnect for the the handbrake would either be driven off the handbrake switch (that's missing) or load sensing which works just like applying the brakes and stalling the torque converter. Eitherway with the handbrake off one would have thought it should move. I get no sense of anything being engaged when I shift the shuttle control lever, not even a click from a relay, and there is a relay right next to the connector and microswitch for the transmission dump pedal.

I've also found the description in the manual for checking the fluid levels utterly ambiguous as it talks about the shuttle reverser, transmission and the gearbox as if they are three separate things with separate level check points. As I see it the 'transmission' comprises a single unit that houses both the automatic gearbox syle 'shuttle reverser' that sits between the engine and a manual 4 speed 'gearbox' and they all share the same oil!

[Slooby]

Trawling through the wiring diagram it looks like the Handbrake/Parking Brake switch is only connected to the warning lamp, there doesn't seem to be any trace for a wire relating to it running to any relays or switches associated with the Shuttle lever or transmission dump. Well, other than the fact that all the warning lamps, their associated senders/switches, gauges, transmission dump relay and feed to the shuttle lever are all connected to the same fuse (6) in the fuse box!

I've read elsewhere that the transmission dump switch on the loader control has a habit of sticking, so I need to take a look at it.

In addition it sounds like you can check for actuator movement without the engine running, so I guess that's tomorrow's fun

[Slooby]

Ha!

Found it!!!

Disconnected the warning buzzer, switched on the ignition and listen for the sounds of relays and solenoids engaging.

First time I tried the shuttle lever, dump pedal and dump button I could here clicking from the relay by the dump pedal and the starter relay, playing around with the controls a few more times and the starter relay suddenly went quiet, gave it a tap and it engaged again. With the engine fired up I could engage forward and reverse once more. So, whether it is the relay itself or the wiring I can't tell, but time to see if I can get a new one to test,it looks fairly generic Lucas...

[essexpete]

Progress!

[Slooby]

Yup, having established that the relays are readily available online, but not found one locally available today, I pulled the cover off the relay and cleaned up the contactors which were a tiny bit furry from burnt on dirt (the inside of the cover was pretty dirty). I've now checked it's still working and am going to put the column shroud back on after working out where to route the loom and secure it.

[Slooby]

One set of dirty contactors inside the Starter Relay:



Eventually got the column shroud back on, after a lot of swearing. Had to give up on my cable tying plans to get the loom to sit nicely in the end and just stuffed the bloody thing where I could get it in the end because the logical routing of the loom meant the gauges wouldn't go back in

But that I hope is that for this problem at least...

[Jeremy Rowland]

Well done Tim it pays to persevere

Jeremy

[Slooby]

Thanks Jeremy, I certainly have to be persistant with this machine!

[Slooby]

Arrrgrgrgrgggghhh

And the problem is back

It would appear that the unless the ignition switch is on the first click, which means the warning buzzer is on and so is the charging light, the solenoids for the dump or starter relay aren't energised and so won't switch when the shuttle lever or dump pedal/button are engaged.

Also when the the ignition switch is in the first position the battery gauge works and the fuel gauge goes backwards, back on '0' and they are disabled

So this is the bit I really don't understand; with most ignition switches you need to be at position '1' for the vehicle to run, but here if I leave it in '1' the buzzer is screaming and the charging light stays on, even with the engine running, but you can drive. Switch it back to '0' you get no drive but the buzzer and ignition light are out, unless you blip the throttle to over 1500rpm then the ignition light comes on dimly and get brighter when you flick the shuttle lever into drive or hit a dump, however neither the drive or dump solenoids click.

Now, with a Lucas iginition switch like the one used on the JCB and Tractors for, well...ever, I always thought that position '1' was for glow/heater plugs (hence the buzzer warning) and once the engine was running you turned it back to '0' as you were now running on alternator power. So duff ignition switch, relay, rectifier on the alternator or whole alternator?

[Slooby]

Hum

Having read this Greg@Hilltop @ Grey Cab Electrics from a couple of years ago, I'm starting to wonder if my problem is charging related all along.

Is the buzzer an indication that the charging circuit isn't working, and the ignition is meant to be at position '1' all the time the engine is running? This would explain why my gauges only work with the switch at '1'...although quite why my fuel gauge goes backwards I've no idea...