VT SS blowing main fuse (SOLVED)

[Skylarking]

Hi,
The heavy 12V cable to the starter is NOT fused. It goes straight to
the starter from the battery.
So a starter motor fault shouldn't blow the main 60A fuse even if there was a
short in the starter when it spun.
I would disconnect the thin wire to the starter solenoid as this would get
its current indirectly via the main fuse.
If the fuse then doesn't blow then the problem is in the starter solenoid.
Cheers.

Everything within the vehicle is fused, whether it’s via the 60A? fusible links located at the positive battery terminal, or the main fuses at the rear fuse box or some other blade type fuse located in one of the fuse boxes.

Fuses exist to protect the vehicle from burning to the ground. So to say the main starter cable isn’t fused is wrong, it is...

Also, the wire gauge within a vehicle varies depending on the circuit one looks at while the fuse associated with that circuit will be sized to protect it’s components and wiring. As such, a wiring diagram is the best thing to have when chasing wiring faults, especially factory wiring diagrams and the associated loom diagrams and connector pinouts. Always replace a fuse with that specified by the manufacturer and nothing else...

Being that the starter control wiring is not a heavy current circuit and normal gauge wiring is used for that circuit, it will melt before a 60A fuse blows!

So I doubt it’s the starter control wiring that is the issue. But it’s been many many years since I’ve looked into the starter wiring though I doubt that’s the faulty part.

Best approach is for OP to look at a VT wiring diagram which should clarify what wires are associated with what function and which fuse will blow when a fault exists.

Still, your suggestion of connection and disconnection of wiring is a good fault finding method when wiring diagrams are lacking (or when previous owner has modded the wiring into some spaghetti abstract or the factory system)...

 

[Skylarking]

sorry but wildfire is correct
cant believe that circuit is not protected

The link I provided includes wiring diagrams that indicate battery connection has fusible link so it would be odd indeed to then have one unfused circuit... I also can’t believe that circuit is not protected but then again it’s Holden...

Must search out the VT service manual as it would have the starter circuit specific diagram which should clarify the situation.

 

[lout]

i checked the genuine diagram and the heavy starter wire is not fused
the main 60A feeds the ignition switch and a lot of other circuits including the starter solenoid

 

[axemurderer101]

Fuses exist to protect the vehicle from burning to the ground. So to say the main starter cable isn’t fused is wrong, it is...

You are wrong lol, starter wire main feed goes direct to battery with no fuse of any kind.

 

[Skylarking]

You are wrong lol, starter wire main feed goes direct to battery with no fuse of any kind.

In older cars the fusible link doesn’t look different to the wire itself and in some cases is indistinguishable to it. Those indistinguishable type fusible links are especially used in old cars stuff. In comparison, the VE and VF fusible link is obvious as it is contained within a large plastic housing around the battery clamp and have clear plastic covers for the very fuse like link within.

But as I said, any unfused wiring is a stupid design within a vehicle as it could result in a vehicle fire if a wiring fault occurs. Heck fusible links were used in 50’s and 60’s vehicles to protect all circuits so can’t see what they wouldn’t be the case with the VT.

So, I’d still think there would be a fusible link somewhere, just not an obviously visible fusible link. If there isn’t one, that’s gotta be the first car I’ve heard of that didn’t have some sort of fusible link on the main battery positive lead and if that’s the case, I’m wrong. But hey that wouldn’t be the first time

i checked the genuine diagram and the heavy starter wire is not fused the main 60A feeds the ignition switch and a lot of other circuits including the starter solenoid

Thanks for checking the wiring diagram... seems it’s one of those “wouldn’t be the first time“ days Now I’m wondering whether the as built differs from the workshop manual in any way

 

[Trevor loves holden.]

The starter doesn't need a fuse as there nothing to shorten out bar the cable, its the solenoid which feeds back thru the car so it needs to be on a fuse.

 

[lout]

i have seen many starter heavy cables rub through around engine mounts and the old tin sump pans so am surprised this is not fused

 

[BowTie]

No fuse on starter main.

Have rebuilt a few with extra insulation.

Maybe, could the alternator be drawing the 60A+ to blow the main fuse while leaving all other fuses ok?

Ampmeter on the charge wire would tell you.

 

[vc commodore]

In older cars the fusible link doesn’t look different to the wire itself and in some cases is indistinguishable to it. Those indistinguishable type fusible links are especially used in old cars stuff. In comparison, the VE and VF fusible link is obvious as it is contained within a large plastic housing around the battery clamp and have clear plastic covers for the very fuse like link within.

But as I said, any unfused wiring is a stupid design within a vehicle as it could result in a vehicle fire if a wiring fault occurs. Heck fusible links were used in 50’s and 60’s vehicles to protect all circuits so can’t see what they wouldn’t be the case with the VT.

So, I’d still think there would be a fusible link somewhere, just not an obviously visible fusible link. If there isn’t one, that’s gotta be the first car I’ve heard of that didn’t have some sort of fusible link on the main battery positive lead and if that’s the case, I’m wrong. But hey that wouldn’t be the first time

You haven't played with cars much have you?

It's really strange, I personally removed the main battery starter cable from the front of the car and moved it to the rear and didn't see any signs of a fuseable link. Just a straight power cable that's got no joins

I've also got other cars that were built in the 70's, that have a starter relay, yet there is no sign of a fuseable link in the main starter power wire. Again a straight unjoined power lead. They have a fuseable link at the starter relay, which when it blows prevents power going to the starter solenoid and engaging the starter motor....

 

[Skylarking]

The starter doesn't need a fuse as there nothing to shorten out bar the cable, its the solenoid which feeds back thru the car so it needs to be on a fuse.

The engine moves so cable which are connected to a component bolted to the motor also moves. There is also vibration that transfers to all cabling within vehile body as it drives down the road. Vibration and movement can and does abrade insulation which can cause a short to ground. If such shorts to ground occur on an unfused wire, it can then cause a fire within your vehicle, especially if the wire is always live

Regardless of whether the VT does or doesn't have a fusable link on the live stater cable, it's not good practice to not protect wiring. Having such cables protected with corregated plastic pipe are a supplement that helps to reduce risk but such should not be a full replacement for fusible links.

Oddly the VT workshop manual I have doesn’t have much info but the wiring remains much the same for engine wiring within VT2, VU, VX & VY. For those later doores, there is a bunch of fusible links and a fusible wire shown in the loom diagrams. Wiring diagrams I don’t seem to have

In any case, it would be more interesting to hear from @Benji_john93 as to what the problem turned out to be than debate fusible links/wires