Fuse melting engine cuts out - help please

@zedders
@snotty

Thanks a million!

So i've moved the big red wire from 9: the top (fused) terminal, to 9 the bottom (unfused) terminal.

Immobiliser still works.
G & Oil lights and gauges still work.
Engine still starts.

If i pull the fuse the engine does not cut out (which it did before).

So this is obviously how it is meant to be have been wired - no idea who or when it was changed!

Obviously i still need to find out if i have a short on that circuit/the cause of the overloading, but for now at least the engine won't cut out if the fuse blows!

So at least some progress has been made. Thanks very much to all who have responded.

I won't drive far before sorting the rest of the electrical issue.

 

Good news.

What wire colours have you got going into the top of fuse 9 now? With luck, they'll be the standard ones.

 

The reason I mentioned caution is that if there is a fault, you no longer have a fuse so your wiring would melt/catch fire. Why not let your man check for faults first?

 

You really should at least have or make a 12 volt test light. Just a probe, light bulb some wire and an earth clip.

With that you can tell if a circuit has 12 volts on it. Poke wire with earth clip to chassis. Light comes on ..

You can also tell if a circuit is draining current. Take the fuse out. Put the earth clip on one side of fuse , probe on the other . If the light comes on then its draining current through the fuse..


Cheapie in a Halfords kit ..


Sealey Automotive test probe also lets you connect power or ground a circuit, measures voltages.. £75..

I flashed a buses headlamps from the tail light terminal using one of these at Techenders..
Confused @Merlin Cat when her bus started making friendly gestures towards another Champagne Edition bus..


The Sealey thing is excellent when its dark and a bulb circuit has failed . Expensive .. if you go on a T2D Boot Camp its one of their money making gadgets. *although I think it was cheaper from T2D than anywhere else.

I also carry a digital multimeter in the bus .. thats under the rear seat so its in the "serious" toolkit, as opposed to the"Rapid Reaction Force" toolkit kept in a tool roll behind the passenger seat including both the testers.

 

Nothing in the top terminal of fuse 9, if i move the big red fuse.
Next terminal down is a smaller red wire from the lower of the top two terminals on fuse 9 - that looks like it is heading to the light relays

Edit: the smaller red wire is actually from the lower (unfused) terminal on 9, it heads to the relays.

 

I switched it back to the fused side once i had done the test.

What is shows me is that once the fault is found and fixed: i could keep the immobiliser and if that 'circuit fails then my engine wouldn't cut out.

 

Cheers Mike

I will at the very least ensure i have one of those 12v test lights

I'm not sure i would know how to use it properly.

I failed physics at school, i wish id paid more attention.
Passed all the rest of my exams, but physics was last lesson on a Friday!

 

I've got a 1973 fuse box and mine seem to fairly closely follow this list
https://www.autogenius.info/volkswagen-bus-t2-second-generation-1969-1979-fuse-box-diagram/
For fuse 9 they list: Auxiliary heater (switch current), Buzzer alarm, Interior light rear.
My interior lights are on the leisure battery, don't have auxiliary heater and never had a buzzer (as far as i know).
I'll try and find a good diagram with the wiring colours etc

The rest of mine fairly closely follows their list.

Main battery
1: Passenger Rear tail light
2: Drivers Rear tail light. Number plate light?
3: Low beam left?
4: Low beam right?
5: High beam left. High beam indicator (dash) light?
6: High beam right (passenger side)
7: Empty?
8: Hazard warning lights, Rear Lights, side lights, dash lights, gauge lights. (Red & white wire in from below)
9: Headlights?, Immobiliser, G & Oil light, fuel gauge (Engine won't run without this fuse). Big red wire out on wrong fused side
10: Windscreen wipers, oil cooler fan
11: Indicators, G & Oil light, fuel gauge (Not immobiliser on this circuit). Pull fuse 11 with engine running and it doesn't stop - Engine runs without this fuse.
12: Brake lights. Horn




Leisure Battery/Leisure fuse circuit
1: Original Interior cab light - (operated by buttons on the door and the switch)
1: Big light (operated by pull switch on dash, plus button on side of light)
2: Fuse removed. disconnected big red cable previously used used for amp
3:
4: Stereo
CHECK: Cig lighter socket
Amp: In line fuse only
Interior Spot lights (powered through amp circuit)

 

Still get your bloke to look at it. As Zed said, there may be something weird in that wiring, and it’ll be unfused.

Also look for a separate fuse for the immobiliser. It should have one of its own, as it’s likely a low-current device.

 

Yes I will do that.

 

The generator and other dash only appear to be on 9 because their actual fuse is fed via the ignition switch which at the moment is wrong side of fuse...if you see what I mean.

 

8 and 9 are both always live.. 10 to 12 live on ignition.. (11 &12 as a pair), 1 to 6 (lights) live by switches.. 7 for whatever you want. Dash gen and oil should be off 11 or 12

Sent from my SM-T580 using Tapatalk

 

Thinking about your fuse situation, ALL your electrics must have been through fuse 9 up to the ignition switch and back to feed "ignition on" fuses fuses, which is most of them?

 

Not really.

When I switched the wire to the unfused bit of 9
The G & Oil light still behaved exactly the same.

 

quite possibly

 

Prob not gen and oil off 9 or they'd always be on... no fuse here means nothing to ignition so all dies..

Pull fuse 11 and coil still gets 12v off no 10 so once running carries on..



Sent from my SM-T580 using Tapatalk

 

Paul, I haven't read thru this thread completely, but gave you got a year correct wiring diagram for you Bus? They are on The Samba, it will help you follow the wires and identify old from new. Apologies, if I am teaching Granny to suck eggs.

 

All the ones on samba didn't seem to relate to mine, but I'll have another look

 

I am confident it will be there, surprised it if wasn't, they seem to have a most years. Once you get your head around how they are drawn, they can be a big help.

 

Have a look on www.vintagebus.com