No Start/No Power Issue (2 Viewers)

[iptman]

I went to drive the 40 yesterday, when I put the key in the ignition and turned to on I immediately got interior power and the seat belt buzz. I turned the key to start it and everything died. The starter didn't click. Pulled the key out and tried again and no electrical power at all. The battery is at 12.6v. I tested the FL and it had continuity. For good measure I swapped the FL out with an old spare I keep in the glove box and I got power again with the ignition on but when I went to start, the same thing happened again. It's an 7/77 CA spec with a completely stock drivetrain and electrical system, aside from a fused 12v line running in to the cab for a fridge. There's no power getting to the fuses.

Any help would be appreciated.

Edit: it's a July 77 not 8/77.

 

[iptman]

I pulled the top clam shell off to test the ignition switch. I get 3.65v on the black/red wire (seems low). When I cycle through ACC and On I get no voltage on any of the other terminals.

 

[Malleus]

You have a bad ignition switch.

 

[iptman]

Bullocks.

 

[45Dougal]

If you unplug the ignition switch and remove it from the equation, what do you get at the connector block?
Can you hotwire it to spin the engine?

Could also be a bad joint in a cable somewhere, like a ring connection at the battery for example, or inside the harness

 

[jcj_78FJ40]

Check to see if you are getting 12v to the Fuse Block. If yes, See if you get 12V across the fuses (some circuits, the ignition will need to be on).

A lot of times, corrosion will build up on those old Glass tube fuse sockets.

Highly recommend a power probe III if you don't already have one.

 

[iptman]

If you unplug the ignition switch and remove it from the equation, what do you get at the connector block?
Can you hotwire it to spin the engine?

Good idea. I just checked and I get 11.6v at the one terminal on the harness side of the plug.

 

[iptman]

Check to see if you are getting 12v to the Fuse Block. If yes, See if you get 12V across the fuses (some circuits, the ignition will need to be on).

A lot of times, corrosion will build up on those old Glass tube fuse sockets.

Highly recommend a power probe III if you don't already have one.

Nothing to the fuse block in any of the key positions.

Yeah, I do need to get a power probe.

 

[45Dougal]

Interesting. You have power at the ignition switch socket (White-blue i think?), but nothing at the same colour wire at the fuse box?
No stop lamps, no headlights, nothing?

That sounds like failed solder joint buried in the harness where the two wires split I think.

Anyone remember exactly where the solder joint is?

 

[jcj_78FJ40]

So zero volts voltage at the fuse block with ignition off (no voltage on the top 4 fuses, no lights, no horn)?

 

[iptman]

So zero volts voltage at the fuse block with ignition off (no voltage on the top 4 fuses, no lights, no horn)?

Top 3 (tail, stop and lighter) and bottom (headlamp) all show 3.65v which is strange to me. The other thing I noticed is the Ammeter needle is right in the middle. I can't remember if that's the resting location or not. The rest of the gauges are resting down to the left.

 

[iptman]

Interesting. You have power at the ignition switch socket (White-blue i think?), but nothing at the same colour wire at the fuse box?
No stop lamps, no headlights, nothing?

That sounds like failed solder joint buried in the harness where the two wires split I think.

Anyone remember exactly where the solder joint is?

Yes voltage on the white/blue wire, although it's now showing 9.25v and earlier it was 11.6v.

No lamps, headlights, nothing. It's like the battery is disconnected.

 

[jcj_78FJ40]

You may have a short somewhere. I would pull the positive battery cable and check for current draw. Definitely disconnect your negative cable if you are going to leave it for the night.

 

[iptman]

You may have a short somewhere. I would pull the positive battery cable and check for current draw. Definitely disconnect your negative cable if you are going to leave it for the night.

Still have 12.6v at the battery. But yeah, I suppose disconnecting the battery now would be prudent.

 

[45Dougal]

Yes voltage on the white/blue wire, although it's now showing 9.25v and earlier it was 11.6v.

No lamps, headlights, nothing. It's like the battery is disconnected.

Now remove the instrument panel and check what you have on each side of the ammeter - this is the source of your white-blue (virtually all power goes through it).

It could well be a loose connection here.
If the ammeter is dead then you can join the two wires together to bypass it.

 

[clrussell]

sounds to me like a battery cable Connection issue.

Step one 1 clean and Tighten battery cables/ ends.
Step 2 follow above advice

 

[iptman]

Now remove the instrument panel and check what you have on each side of the ammeter - this is the source of your white-blue (virtually all power goes through it).

It could well be a loose connection here.
If the ammeter is dead then you can join the two wires together to bypass it.

Does the white/blue wire bypass the ammeter? If so then it'd make sense it could be that.

 

[45Dougal]

Does the white/blue wire bypass the ammeter? If so then it'd make sense it could be that.

No, the white wire goes from the battery to the ammeter, then through the ammeter in order to feed the white-blue.

All current needs to pass through the ammeter (disclaimer for those with external shunt type..).

If your ammeter connections are bad then you'll have no power anywhere.

 

[jembourbe]

Ground connection

 

[jcj_78FJ40]

Does the white/blue wire bypass the ammeter? If so then it'd make sense it could be that.

Now remove the instrument panel and check what you have on each side of the ammeter - this is the source of your white-blue (virtually all power goes through it).

It could well be a loose connection here.
If the ammeter is dead then you can join the two wires together to bypass it.

To add, measure voltage at the ammeter with the wire connected, if it reads low then measure the input harness (passenger side, I think) disconnected from ammeter.

See if the readings are significantly different. 3.5v indicates that there may be an unwanted series load.

Also, Blown alternator diodes and stuck starter solenoids will cause wonky issues and potentially draw a lot of current. Pretty easy to rule these out by unplugging them (both starter solenoid wires and voltage regulator).