Starter motor wiring on a 1993 JCB 3CX

[topkit]

Anyone on here got a project 8 3CX, i had a friend helping me (think) at the weekend my machine would not always start, so i noticed the positive battery lead was going verdigris, i fitted a new one also removed the earth and cleaned it, i also had a spare good starter motor in the workshop which is where my mate helpfully removed it but did not note the layout, i cant workout which cable goes to the casing on the back of the starter motor, i have a wire with spade terminal which is for the starter solenoid, then i have a bunch of all yellow wires wired into one ring connector, also a second bunch of wires on another ring connector and lastly the positive lead from the battery, i looked at the starter on my project 12 but its totally different to the project 8, i hate wiring diagrams too which does not help matters, so my question is where the the 4 connections go to. Pictur of starter attached showing the connection at the back of the starter casing. Thanks in advance

 

[Gecko]

This should get you back to where you started

 

[V8Druid]

mine stopped starting a long while back ... that was an additional earth on ring terminals on that post ... you'd think it was adequately earthed, bolted to the engine block, but that post must earth summat inside ??? not had an issue since .. would make for a good immobilizer who'd think of those earths

 

[topkit]

Thanks for that i wonder what my additional bunch of wires do, i will get a meter on them and see if they have any current running through them, I think i will run an additional earth from the back of the starter to somwhere on the engine block an additional earth wont hurt.

 

[Gecko]

an additional earth wont hurt.

https://www.planttalk.co.uk/threads/jcb-wiring-fire.1075/#post-27126
never underestimate the potential benefit of an extra earth!

Ideally, the -(ve) battery lead would go to that stud and continue to the chassis using a flag terminal so even if one connection comes loose, the cable has no joins

 

[topkit]

Well finally got to check the wiring today got soaked to the skin as we had yet another downpour here, i cant quite work it out i have the loom with 4 or 5 yellow wires and single wire which goes to the solenoid no probs the other cable has 4 thick yellow wires on one original ring connector when all of these are on the starter terminal i popped the positive back onto the battery and i get the ignition buzzer going in the cab? That is without the key being turned, looking at the back of the ignition switch i have 6 wires all yellow the codes are cab #000- going to connector 1 or 2 for the battery, then duel wires Cab #200b going to terminal 3 or 4 for starter motor, cab #001 to terminal 5/6 Ignition, wire Cab #004 to terminal 7 neutral start, wire Cab #003 to terminal8/9 thermo pre heat, apart from the ignition switch being wired incorrectly why would the buzzer be going before the key is turned! Confused.com

 

[Gunners]

Doesnt the buzzer relate to the oil pressure? Of which there isnt any before the key is turned and engine started. Cant say the old black cab 3cx in the yard does it but then theres a lot that machine doesnt do anymore! But all my more recent JCB kit works that way.

 

[topkit]

The buzzer is going when i put the positve cable back onto the battery without the key being turned normally it would be silent until you turn the key then the buzzer would start.

 

[Gecko]

That is without the key being turned

this suggests either there is a problem with the ignition switch (first contact not opening) or the wiring is not quite correct yet.

Doesnt the buzzer relate to the oil pressure?

The buzzer is the general warning (for the P8 at least). It's to get your attention so you go looking for the real problem.

 

[V8Druid]

The buzzer is going when i put the positve cable back onto the battery without the key being turned normally it would be silent until you turn the key then the buzzer would start.

sounds like you have a wire earthed or energised ... that shouldn't be ... more likely energised as the switch is off but stray energy coming from somewhere .. i.e. the back end of the starter as that's the only wires you've had off
are there any singles with ambiguous locations ??

 

[topkit]

Nope all i have is rge battery positive, four large wires going into one ring connecter, and a second ring connector with 4 smaller wires and also the single wire on a spade terminal that goes onto the solenoid, The machine had been fitted with an old type lucas ignition switch and i have the correct brand new JCB type ignition switch. My reason for going through the ignition is when i first got it was temremental on the switch you could tutrn the key and nothing would happen and then you fiddled with the connections and it would start, The battery is good and fully charged.

 

[topkit]

I have been doing a bit more research and it looks like my 3cx should have a 4 position ignition switch and i have a feeling it has a five position one fitted so i am now wondering if that would effect things, I cant see anything else that is incorrect on the ignition side it has to be something simple.

 

[Gecko]

As a quick test, take the connector off the ignition switch and see if it's still buzzing

 

[topkit]

Got it all sorted today there were a buch of wires that went to earth on the starter everthing else cleaned and done up tight and she fired up straight away, Happy days.

 

[V8Druid]

Got it all sorted today there were a buch of wires that went to earth on the starter everthing else cleaned and done up tight and she fired up straight away, Happy days.

mine stopped starting a long while back ... that was an additional earth on ring terminals on that post ... you'd think it was adequately earthed, bolted to the engine block, but that post must earth summat inside ??? not had an issue since .. would make for a good immobilizer who'd think of those earths

that's the ones, had me foxed too

 

[Gecko]

Remembered to take a pic of my starter solenoid. This is a late P8, which probably explains the differences

 

[Duff]

Got it all sorted today there were a buch of wires that went to earth on the starter everthing else cleaned and done up tight and she fired up straight away, Happy days.

Hi topkit I have same issue pulled dash half apart changed ignition etc if you could send me a pic of your starter that would be great

 

[Duff]

Thanks all got sorted as ye said had a bunch of yellow earths in wrong place

 

[Gecko]

Thanks all got sorted as ye said had a bunch of yellow earths in wrong place

For future reference, all the wires have individual numbers printed on them to indicate their function.
Earth wires are all #600 followed by none, one or two letters

Some examples: