3cx Grey Cab 1990 - Loose Wire -Help!

[BarryR1980]

Firstly hi all!

I have been sneaking around in the background trawling through all the posts over the last 6 to 8 weeks since I purchased my first backhoe.

I bought a fairly rough 1990 JCB 3cx 4x4 site master.

Unfortunately I purchased the machine myself, only armed with the research I had completed online, along with the Beginners guides to checking a backhoe over on you tube. If there is any good news to be gained from the whole experience so far, its that my mechanical skills have significantly improved over the last 8 weeks, and if I ever went to buy another backhoe again I would know exactly what to look for

Anyway, after a long list of problems that I have been able to address through the various articles on the site, and the service manuals in the download section, like burned out Altenator, new battery, blown exhaust manifold gaskets, leaking king post carriage, blown planet gears in front hub, dirty diesel blockage, forward reverse shuttle solenoid cable failure etc... I have reached a problem that I need a bit of a steer on.

Went up tonight to wire in a usb charger point for the kids (getting a bit bored of sitting in the digger every weekend and they need a method of keeping their gadgets charged up - poor things ) when I was routing the cables down under the machine I found another loose cable. The problem I have is that this machine was farmer owned in its past life and it was subjected to a fairly dismal rewire which consisted of keep the essentials functional and scrapping everything else. A lot of the rewire was completed using domestic cable joiners, which I’m rectifying as I go, and this is what caused the Altenator and all the wiring to melt, but that’s a different story.

Anyway, the loose wire was hanging on the lower left side of the engine, it must have been snagged on something when I was clearing the site. It’s connected to a cable joiner which has 3 cables from the original machine harness, 2 of the 3 wires are connected to the fuel injection pump the 3rd is the one that is hanging loose. In the same general area there is another original harness, again with joiners and cables connected to the starter motor.

Do any of you know what the cables from the harness that goes to the fuel pump should be connected to? I’m hoping there are only 3 cables and 3 locations and this going to be really easy! Stupidly I didn’t check the colour of the wire on the harness side, I was getting to it and the kids started killing each other in the shed so I decided it was time to head for home! If this is likely to be a big help I can go back up again tomorrow afternoon and check.

Some further information, up until I fixed the Altenator I only had one warning light on the dash and a buzzer (top right light, it is either engine or transmission oil pressure light), when I started the engine the light went out and the buzzer stopped. After I fixed the Altenator I got 2 lights on the top right when the no charge light came back on.

I notice tonight the oil pressure light no longer comes on, I now only have the no charge light and buzzer at startup. I’m hoping this can be used as a clue to help identify where this cable has disconnected from!! I definitely had both lights up until tonight when I noticed this wire loose.

Any help would be greatly appreciate, as I would love to get it sorted before the weekend to get me back to my self build!

Barry

[BarryR1980]

After I posted I realised that I had left the bloody crimper that I borrowed from the electrician at work behind me, but every cloud has a silver lining I suppose. When I went back up I checked the cable colour. It’s a thin gauge yellow wire with what looks to be a brown stripe. It’s the one closest to the bottom of the picture of my rats nest of wiring!

[Slooby]

Welcome Barry, I can feel your pain with what I have had to 'fixed on my older machine!

I'm going to sound like a broken record here, but have you consulted the wiring diagrams in the manuals you have downloaded? I've only got the one for the black cab to hand, and looking at the ones in that I couldn't see a yellow/brown (which should be 'YN' in the naming convention they used) listed :/

[BarryR1980]

Yes. Had a look through the manual and couldn’t see a YN wire listed. I’m wondering it is was originally white and has discoloured over time. I’ll have another look.

The only thing is that it is noticeably smaller than all the other wires in this harness, so I was hoping this would give some clue as to what it is

[Slooby]

Smaller gauge suggest either signal wire or low current device. Have you tried to trace it back to anything in the cab? Not easy I know, but seeing if there's anything behind the instrument cluster with a similar coloured wire might help

[BarryR1980]

Hi Slooby, thanks for taking the time to respond! Got back up for a while tonight and managed to establish that it was discolouration of the cable after I stripped back some of the shielding around the harness. Turned out to be white brown, and from the wiring diagrams established it was as simple as connecting it back to the oil pressure sensor.

All seems really logical now, especially considering the loss of the dash light, but I’m my mind I would have assumed the light would have failed on rather than off.

Anyway, happy days, I’m back in action for the weekend and I learned another little bit about my new toy!

[Slooby]

Good stuff!

I was out in our orchard this evening pottering about in mine trying to d9 some grading while avoiding the daft chickens who it seemed wanted to be in the bucket raking through the soil I was moving about.