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selectamatic wiring

Posted: Mon Dec 30, 2019 3:45 pm
by Mossop
Hi , having trouble with my warning lamps, when I bought tractor all the warning lamps were broken so I replaced with new , but when I did this the warning lamps glow faintly when ignition switched off , but they don't come on when the ignition is switched off , have checked all the earth straps and cleaned them to no avail , also the ignition switch has only three double connectors , I have four wires , green , white , white / red and brown . Can anybody she's any light on the order they go in / any ideas what is going on with my warning lights , any help greatly appreciated

Re: selectamatic wiring

Posted: Mon Dec 30, 2019 5:12 pm
by ollek
Before giving any sugestions, we will need to know more about your tractor. Model and manufacturing year or serial numbers are the most vital informations needed.

Re: selectamatic wiring

Posted: Mon Dec 30, 2019 5:38 pm
by Mossop
Hi sorry 990 selectamtic , 1968 , number 805774 and it's still on dynamo

Re: selectamatic wiring

Posted: Mon Dec 30, 2019 6:29 pm
by ollek
Study the manual you will get by opening the following link https://drive.google.com/drive/folders/ ... Dh6M2k0bVk and click on Tractor Service Manual 770-1412. (Covers models 770 780 880 885 990 995 996 1200 1210 1212 1410 1412 3800 and 4600. Twenty three (23) chapters) You will fnd the Electrical System in manual part W.

Re: selectamatic wiring

Posted: Mon Dec 30, 2019 6:56 pm
by Mossop
Hi yeah I have a repair manual but all the models covered in that have four separate connectors where as my one has only three double connectors , it is a Lucas 128sa

Re: selectamatic wiring

Posted: Mon Dec 30, 2019 10:32 pm
by philedge
Are you sure you have the right switch? Youll need connections for the following 4 circuits-
12v supply to the switch
12v out to the indicator lights and any guages fitted
12v out to the thermostart/manifold heater
12v out to the starter

Thats 4 separate connections youll need

Re: selectamatic wiring

Posted: Tue Dec 31, 2019 1:55 am
by ollek
Well, not all tractors have the Thermostart/manifold heater. Please check to see if there is a Thermostart valve in the inlet manifold. If not, then a 3-position ignition switch is used. A 4-position ignition switch is used if there is a Thermostart valve in the inlet manifold. If the Thermostart cold start aid is not needed, then you can use the 3-position switch and simply leave the lead to the Thermostart not connected to the ignition switch.

Re: selectamatic wiring

Posted: Tue Dec 31, 2019 3:50 am
by dbdgc
On my 1966 Model

The green feeds the oil and charge warning lamp
The white feeds the temp gauge
Brown is Live feed to the switch
The last wire goes to the solenoid

White and green are connected to the same terminal

Re: selectamatic wiring

Posted: Tue Dec 31, 2019 8:06 am
by philedge
A lucas 128SA seems to be a 4 position switch with 3 double connectors and 1 single connector. If its a 128sa thats being used, maybe the single connector has been broken off?

Re: selectamatic wiring

Posted: Tue Dec 31, 2019 7:23 pm
by Mossop
ollek wrote:
Tue Dec 31, 2019 1:55 am
Well, not all tractors have the Thermostart/manifold heater. Please check to see if there is a Thermostart valve in the inlet manifold. If not, then a 3-position ignition switch is used. A 4-position ignition switch is used if there is a Thermostart valve in the inlet manifold. If the Thermostart cold start aid is not needed, then you can use the 3-position switch and simply leave the lead to the Thermostart not connected to the ignition switch.
Hi yes I have the thermostat valve , the switch is on the right hand side under the diesel tank , the wire comes into the switch from the starter solenoid then out to the thermostat . As you've probably guessed electrics are not my strong point , all seems a bit of jiggery pockery to me , would rather have a stab at doing it myself than pay an autoelectrician

Re: selectamatic wiring

Posted: Tue Dec 31, 2019 7:25 pm
by Mossop
philedge wrote:
Tue Dec 31, 2019 8:06 am
A lucas 128SA seems to be a 4 position switch with 3 double connectors and 1 single connector. If its a 128sa thats being used, maybe the single connector has been broken off?
Yes when I put the number into Google it comes up with the four connectors but that is definitely the number on the switch , it doesn't look like anything has broken off

Re: selectamatic wiring

Posted: Tue Dec 31, 2019 7:26 pm
by Mossop
philedge wrote:
Mon Dec 30, 2019 10:32 pm
Are you sure you have the right switch? Youll need connections for the following 4 circuits-
12v supply to the switch
12v out to the indicator lights and any guages fitted
12v out to the thermostart/manifold heater
12v out to the starter

Thats 4 separate connections youll need
Hi it looks to be original but that's not to say it is

Re: selectamatic wiring

Posted: Tue Dec 31, 2019 7:28 pm
by Mossop
philedge wrote:
Tue Dec 31, 2019 8:06 am
A lucas 128SA seems to be a 4 position switch with 3 double connectors and 1 single connector. If its a 128sa thats being used, maybe the single connector has been broken off?
Hi yeah when I Google it it comes up with the four connectors , but it's definitely that number on the back of the switch and doesn't look like anything broken off , as I said there doesn't seem to be a double three connector in any of the wiring diagrams in the repair manual

Re: selectamatic wiring

Posted: Tue Dec 31, 2019 8:21 pm
by ollek
Why dont you look at the engine inlet manifold. If there is a Thermostart unit, then you need a 4 position ignition switch. And by the way, forget the connectors for a while and turn the key and feel how many positions there are in the switch.

Re: selectamatic wiring

Posted: Wed Jan 01, 2020 6:50 pm
by philedge
Mossop wrote:
Tue Dec 31, 2019 7:28 pm
Hi yeah when I Google it it comes up with the four connectors , but it's definitely that number on the back of the switch and doesn't look like anything broken off , as I said there doesn't seem to be a double three connector in any of the wiring diagrams in the repair manual
Seems the 128SA is the general style of the switch and theres several variants with 3, 4 and 5 connectors on the back. If you google "lucas 30792" youll find a 3 connector variant. I think there should be a part number printed on the side of the switch which will tell you exactly which variant you have- is it there?