Wiring starter motor to switch

[ripvan1]

I'm trying to make sense of previous owner's wiring (with difficulty) and need to start with starter motor connections to key start - would the electrical bods give me some guidance as to which terminal connects to which.

Also in the top photo the uppermost terminal seems to have two connections (smaller spade and larger one) why is this?

Thanks

 

[VicS]

In the upper picture the two stud terminals are the switched contacts. One (the LH one) goes to the starter motor itself The other has the main cable from the battery connceted to it.

The sparate small spade is the connection to the coil ( the other end of the coil is internally earthed )

The spades on the RH stud are for connection of other circuits to the main positive supply. The larger one may be where the alternator output is connected.

On the switch
1 is the feed (Main positive probably from one of the spade on the large terminal of the solenoid)
2 is for auxiliary circuits controlled by the switch. Intruments warning lights etc
3 is for the preheating ( Glowplugs) which may be themselves connected via a realy
4 is the connection to the starter solenoid coil

BUT check it with a meter! I am not entirely happy about the above

 

[David2452]

The bottom picture looks more like an ignition switch than a relay to me.

Oh, you edited that bit out so I assume you think so too on reflection.

 

[VicS]

The bottom picture looks more like an ignition switch than a relay to me.

Oh, you edited that bit out so I assume you think so too on reflection.

Yes I realised that when I tried to look up the number!

But can you help any further with the switch wiring...... there seems to be several variations for a 128SA

 

[David2452]

I think you are right in your suggestion on the switch functions Vic, but as you also rightly say, it is very easily confirmed in moments with a test lamp or miltimeter prior to cabling it all up. I would also suggest replacing the switch with an momentary anti clockwise function too, in order to operate the stop solenoid assuming it is not either petrol or a cable pull to stop if diesel, or a (rare on a boat) energise to run solenoid. Really I think we need a bit more info on motor fitted to be some more help to the OP.

 

[ripvan1]

Thanks for replies, engine is 2 cylinder Petter Lister diesel (old)

Vic the LH stud is wired back onto starter motor as you say
The RH stud has the positive battery cable attached

The separate small spade is the connection to the coil ( the other end of the coil is internally earthed )

Where do I connect this small spade to? (Coil? where's that)

On the switch
1 is the feed (Main positive probably from one of the spade on the large terminal of the solenoid)
2 is for auxiliary circuits controlled by the switch. Intruments warning lights etc
3 is for the preheating ( Glowplugs) which may be themselves connected via a realy
4 is the connection to the starter solenoid coil

BUT check it with a meter! I am not entirely happy about the above

Glowplug connectors are on top of manifold, are you saying Number 3 on switch goes direct to these ?
I've got a meter - how do I check things (in simple language please)
Also there's a 5th spade on the key switch - has this a use

Thanks all again

 

[VicS]

Coil = the solenoid coil So the separate small spade will go ... if i am right about the switch ... to terminal 4 of the switch.

Again if I am right about the switch, glowplugs to terminal 3. BUT that could be via a relay ... is there a relay that might do this?


Check the switch using a meter on its lowest ohms range or using the contiuity buzzer if it has one.

Turn to the fully off position.
Connect one lead to terminal 1 check that there is no continuity ( ∞ resistance) between 1 and the others

Turn one position clockwise. Check that you now have continuity between 1 and 2 but still no continuity with 3 and 4.

Turn one more position clockwise. You should have to hold it in this position. Check that you have continuity between 1,2 and 3 but not with 4.

Turn one more position and hold it there. Check that you have continuity between all four connections.

If that all checks OK then the switch wiring will be as I suggested but I dont know what the additional spade is for which is one reason why I am not sure i have it all correct

If you find any differences check which is connected to which in each position and report back.


Meanwhile study the "Boat Electrical notes" on Tony Brooks' website http://www.tb-training.co.uk/


I suppose you dont have an engine wiring diagram.
Wondering if the keyswitch is not original

 

[ripvan1]

Thanks again Vic - will certainly read through the tb training site - could you recommend an idiots guide book that I could have on board ?

Edit: just noticed your query about whether I have a wiring diagram and I do have a handbook that (i think) may have them in - I have to say tho' that those diagrams confuse me a bit.

 

[VicS]

Thanks again Vic - will certainly read through the tb training site - could you recommend an idiots guide book that I could have on board ?

Edit: just noticed your query about whether I have a wiring diagram and I do have a handbook that (i think) may have them in - I have to say tho' that those diagrams confuse me a bit.

There are several books about. The definitive one is Calder's book but perhaps not the best choice as an "idiots guide". Best idea i think with books is to look at them and choose the one that suits you best.

Some wiring diagrams are very difficult to follow. If you can scan or even photograph yours and post it it will be a great help in helping you.

 

[ripvan1]

If you can scan or even photograph yours and post it it will be a great help in helping you.

Can do but away to Malta for 2 weeks on Saturday so will do so on return

Thanks