No power to dash, no crank, no start. Fusible link help

[kapitein]

Hi folks,

Ive already done my share of googling, but looking for more insight if possible,

86 C20 454. Whilst starting the car today, it got running and then just quit.

Ive got no power to the interior, no crank, no start.

Interestingly the lights, interior clock, interior lamps (headlining) and horn still work. Everthing else is dead.

The car did this a month back too, after being stood for a few weeks it wouldnt start (with these symptoms).... after about 50 times turning the key off/on it suddenly sprung back to life and has worked flawlessly again, until now.

- We have no power coming to the interior.
- Have removed, cleaned, checked the big firewall plug, looked OK. No oxidisation etc.
- Fuses and circuit breakers on the interior fuse box all OK
- Main fuse on the bulkhead is OK and has 12v both sides.
- There is no power to the IGN switch on the steering column

Ive got 3 fusible links down by the starter and 1 close to the firewall.

With the symptoms above, considering what still works, would there be 1 particular fusible link to check before any other?

Would appreciate any/all input.

Thanks

 

[Jgonick]

Check for voltage on the junction block- if you have voltage there, check the fusible link coming off the junction block (going to bulkhead)- If you don’t have voltage on junction block, check the fusible link on the red wire coming from the starter than runs to the junction block.

Power comes from starter to junction block through bulkhead to ignition switch.

 

[Jgonick]

Side note- I would also check all your connections on the starter and make sure they are all in good shape and tight- fusible links can go bad overtime, but usually there is a reason a fusible link goes bad- mainly high current (from a short). Loose connections can be the cause of higher current also.

 

[83Stepper]

Check for voltage on the junction block- if you have voltage there, check the fusible link coming off the junction block (going to bulkhead)- If you don’t have voltage on junction block, check the fusible link on the red wire coming from the starter than runs to the junction block.

Power comes from starter to junction block through bulkhead to ignition switch.

Definitely start here. If you've got juice there, check at the bulkhead connector in the engine bay side with it disconnected from the firewall. If you've got juice there at the bulkhead engine bay side connector, more than likely you could have a short to ground inside the cab that's causing it to not receive power inside the cab. Had this issue with my 77 C10. Had power at the fusible link and no power whatsoever in the cab. Disconnected the bulkhead connector at the firewall and had power at the connector on the engine bay side. Ran a continuity test from the hot lead coming into the cab and a good known ground in the engine bay and she rang out like a siren singing her death song lol. Spent almost a solid week chasing that damned short, but eventually found it and got it sorted out.

 

[Jgonick]

Interestingly the lights, interior clock, interior lamps (headlining) and horn still work.

Just so you know- Power for these all come from the other red wire connected to the starter.

 

[kapitein]

Ive got a nice healthy 12.65v on BOTH the red wires at the plug on the firewall (engine bay side)......

So, as best I can tell, my next port of call should be the IGN switch, right?

Having 12.65v at the plug on the firewall rules out any engine bay (fusible link) shennanigans....

 

[kapitein]

So, been doing some more work and happy to say - fixed!!

Had 12.65v also at the plug by the IGN switch.

Removed IGN switch and took it to pieces - it didnt look great inside, and the primary contact looked worn and sooty as hell. Swapped that lil contact for another one inside the switch, put back together and it lives!

So this one had all the frikkin symptoms of a bad fusible link, but in the end its an IGN switch failure. It misbehaved once, and then complete failure. So it can happen that way too.

Got a new switch on the way, but happy its an easy fix

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