Instrument panel amperage question

OBwan

Member
78 3600 Diesel.

Replaced the instrument panel with an aftermarket. In trying to sort out the panel I did a lot of wiring chasing and repairs. I believe the rear harness is in good shape per the wiring diagrams. Still nothing on the gauges. The panel lights work that are fed from the light switch. I have one wire (original Brown w/Blue)running from the ignition switch to the panel. It has a fuse connector with a 3 amp AGA fuse but keeps blowing the fuse. I have 13.8 volts to the fuse connector and continuity from the opposite connector to the instrument panel. Not sure where the amp draw is, how to measure and fix. The wiring diagram shows a hot running to all three bulbs and the wire to the voltage stabilizer. The panel bulbs worked when I initially hooked everything up. Could I have messed up the connection of the hots or maybe it's an issue with the other wires that feed the bulbs. As I think about it the fuse might have blown when I started the tractor. Appreciate any thoughts.
 
Remove the oil and generator bulbs and see if the fuse still blows. that fuse just feeds those two bulbs and the fuel and temp gauge.
 
(quoted from post at 15:16:50 03/11/18) 78 3600 Diesel.

Replaced the instrument panel with an aftermarket. In trying to sort out the panel I did a lot of wiring chasing and repairs. I believe the rear harness is in good shape per the wiring diagrams. Still nothing on the gauges. The panel lights work that are fed from the light switch. I have one wire (original Brown w/Blue)running from the ignition switch to the panel. It has a fuse connector with a 3 amp AGA fuse but keeps blowing the fuse. I have 13.8 volts to the fuse connector and continuity from the opposite connector to the instrument panel. Not sure where the amp draw is, how to measure and fix. The wiring diagram shows a hot running to all three bulbs and the wire to the voltage stabilizer. The panel bulbs worked when I initially hooked everything up. Could I have messed up the connection of the hots or maybe it's an issue with the other wires that feed the bulbs. As I think about it the fuse might have blown when I started the tractor. Appreciate any thoughts.
e sure the voltage stabilizer is well grounded!
 
An early 3600 cluster would have a voltage stabilizer, a later one would not. Do you have the correct one? The cluster backlighting is fed from the light switch. The oil and charge indicator lamps are fed from the key switch. The voltage stabilizer is frame grounded to the cluster. The cluster ground must be good.
 
I blieve there is a diode between the air filter restriction light and the oil pressure light so that all three lights will come on when turning the key on.

As others said...unplug the voltage stabilizer first from power.. if it still blows the 3 amp fuse, I would be then looking at each bulb socket for a bulb spring that is shorting across both contacts.
 
The cluster on the tractor as I received it had a voltage stabilizer. This pic is also on another recent thread. As I found out the wiring on my cluster was very jacked up. Bulbs in the wrong position the hot and the ground on the same spade connector, wires crimped together. It took a while to sort it out. I'm confident the ground is good, but I will check again. I guess I will pull some bulbs and see what happens. I was surprised I didn't get any movement on the fuel gauge when I applied power. All I know is that the wire is good from the sender.
a260944.jpg
 
Update: Disconnected fuse link and checked voltage. I have 12.8 across the battery, running I have 14 across the battery and 12.7/13.8 at the fuse link. Checked grounds and tightened ground blade screw. Removed the three bulbs for Gen, Oil Press and Air Filter, cleaned bulb connectors, taped over hot leads to prevent a connection and installed new fuse. Voltage at stabilizer wire connector is 13.8 running and 12.7 on battery. Connected wire to stabilizer showed 12.7 volts at spade connector, grounded out fuel level sender wire and gauge responded. Shut off tractor, switch off, disconnected stabilizer wire connector and installed Gen bulb. Switch to run, Gen light on, Gen light off after start. Voltage at stabilizer wire connector is 13.8 running 12.7 on batt. Connected Stabilizer wire connector to stabilizer and after a few minutes the gen light comes on. Voltage across the stabilizer is 6 volts. Voltage on either side of stabilizer was 6 volts. I noted the Gen light got brighter as I checked voltage with multi-meter, I used the blade on stabilizer and ground connector on back of cluster. Remove Stab wire and at wire connector voltage was 13.8/12.7. Reconnected Stab wire, Gen bulb and added the Air Cleaner bulb. Switch to Run both lights on, both lights off after start voltage 6 volts at stabilizer. Tractor off, switch off add oil press bulb, switch to run fuse blows. Cleaned O/P bulb connector reinstalled bulb, new fuse, lights come on in Run position but blow fuse when switch to start.

Not sure whats going on with the Gen light. Would adding another 3 Amp fuse before the fuse connector just for the bulbs do anything other than isolating the bulbs and cluster?

Thinking of replacing or redoing the hot wires, connectors in the bulb socket.
I know I am missing something.
 
(quoted from post at 20:37:02 03/11/18) The cluster on the tractor as I received it had a voltage stabilizer. This pic is also on another recent thread. As I found out the wiring on my cluster was very jacked up. Bulbs in the wrong position the hot and the ground on the same spade connector, wires crimped together. It took a while to sort it out. I'm confident the ground is good, but I will check again. I guess I will pull some bulbs and see what happens. I was surprised I didn't get any movement on the fuel gauge when I applied power. All I know is that the wire is good from the sender.
a260944.jpg

Okay,, I think i see a ground wire on one of the the outputs of the v stabilizer.. meaning that it might have destroyed the vstab.... and that is drawing more current than normal?????? Your test appears to tell me that you can run vstab and no bulbs and do ok, or or or you can run bulbs, with no vstab and do ok,, but when you run both, you pop the fuse??? and then the gen bulb dimly lights via/though a weak ground via the defective vstab,,but only when engine is running...?????

Little hard to follow.. but if thats correct??

Make sure bulbs are correct type and not drawing too much current... ( I doubt this is the prob).. check current flow into the vstab... with a current meter capable of reading 3 amps and see actual draw...... and could be one of the gauges is drawing too much current on the down side of vstab, but doubtful.....
 
That setup in the picture is long gone. The bulb socket at the top is either the oil pressure or air filter. The cluster lights were stuck in the lower holes, all jacked up. Now has a new cluster and some wire repairs. The ground is connected to the ground spade next to the tach input where it should be. All four hot wires (stab and three bulbs)come together in one soldered joint. Is it possible it has too much draw or resistance at that joint and is popping the fuse?

All bulbs are new. When I quit for the day I had the tractor off, switch on run, the O/P bulb out and hot taped off and when I stuck the cluster in the hole it looked like when it touched the dash the fuse blew.??
 

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