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Electrical System David Brown 990

D

Deep Green

New User
Hi
I am very very new to the world of tractors, least of all old ones, som please bear with me..
I recently purchased an old DB 990 in good working order.
It was very greasy so I degreased it and cleaned it up a little.
It also had what seemed to be many redundant wires hanging our of the dashboard area and also around the alternator/generator. All of the lighting system has long gone, so I suspect a lot of this wiring is no longer in use, so I tidied them up and tucked them away.
Problem now is the tractor has no power - nothing. It would appear that I have disturbed a critical circuit and need some assistance in tracing and checking critical circuits from the battery right though.
Can someone help with a simple ignition wiring diagram for this tractor? David Brown 990 model.
Thank you in advance.
Deep Green
 
The link would be accurate for a new tractor. Changes made, such as putting on an alternator instead of a generator, or changing gauges. might make a
drastic difference. I would differ in your original description. It was running and seemed to drive OK. If you know electrical systems, Go for it. If
you never used a hand held Volt Ohm Meter, get help and purchase cold malted beverages before starting. Jim
Diagram
 
The 990 is a diesel and nothing about the electrical system should have any effect on how it runs.I'd be looking for something that may have gotten moved or altered going to or on the
injection pump.The fuel stop rod has to be pulled back toward the driver for the tractor to run that may have been change with the washing.
 
Typically when a system totally looses all electrical, it involves the basic circuitry from the battery to the main accessory feed.

You will need a test light or volt meter.

If you can, turn on any electrical accessories, the engine run solenoid, anything to put a load on the electrical system.

Start at the battery posts themselves, not the cable ends, but the posts.

Once you establish there is voltage there, that determines there is some battery current to work with. Then start systematically moving one meter/test light lead at a time until you find where the power stops.

Once you trace power to the starter solenoid, you will find a smaller wire doubled under the positive battery cable stud. Start tracing that wire. It will feed the amp meter (if equipped) and the rest of the electrical system. There is often a fuse link in this wire. If something shorted to ground it will have taken out the fuse link. If the fuse link is burned, look for a shorted wire.
 
(quoted from post at 17:51:28 09/07/20) The 990 is a diesel and nothing about the electrical system should have any effect on how it runs.I'd be looking for something that may have gotten moved or altered going to or on the
injection pump.The fuel stop rod has to be pulled back toward the driver for the tractor to run that may have been change with the washing.
Click to expand...

Thanks. My bad description. I have no power from the battery when I try to start it. Fuel stop rod is in correct position but not cranking when turning key.
 
You wrote "Can someone help with a simple ignition wiring diagram for this tractor? David Brown 990 model."

Unfortunately there is no simple wiring diagram for these tractors.

The electrical system on these tractors was designed by Lucas, known in the motorcycling community as "The prince of darkness" because of their complexity and unreliability. Lucas never used a simple switch
and a wire when a switch, 3 relays and 14 wires could be used in their place.

I worked in Case service from 1973 until 2015.

Good luck!
 

Hilltopper has it right. The Lucas wiring system isn't what we're used to. If you know someone who is willing to "American-ize" the wiring, it will make things a lot simpler. Your no crank issue can be something as simple as a bad ground. Clean all the connections in the starting system and see what happens.
 
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