Fuse box circuit breaker question

[Chuck Step-a-side]

I have a 1984 Siverado Stepside that has a circuit breaker located above the turn signal flasher relay on the fuse box. I'm having intermittent starting issue after the truck warms up and I have traced 2 red wires from the start switch on the steering column and found that one of the red wire went to this circuit breaker. It is the first time that I have encountered this metal case circuit breaker and I want to know what is it protecting in the wiring circuit and how to test if it's weak or faulty.  Thanks, Chuck

[bd]

That should be a 30-amp auto-reset circuit breaker.  It protects the power door locks.

Is the starting issue "no crank" or "cranks okay but doesn't fire?"

[bake315]

Hey Chuck,

Just sort of spitballing here, but if this is falling in the "cranks, but no-fire" category, my '79 K10 sometimes takes several more cycles to fire and run, but ultimately does start after being in operation a while.  Back when I had it, my '74 would get it bad.  Sometimes I would have to wait upwards of a half-hour for it to start.  Both start(ed) at the touch of the key otherwise.  Thermal issue?  Or something maybe affecting the resistance of the ignition circuit?  In the latter case, I noted significant damage in the wire leading to the back of the fuse block, creating enough of a resistance issue that it wasn't conducting a full 12 volts to the ignition system.

Just my .02 (adjusted for inflation),

bake315

[Chuck Step-a-side]

I have no power door lock or window power. Would the breaker still be needed?

The starter will crank the motor at first start. If I take a little trip and stop and then start again I will get no start. When this happens the starter will click one short time and the red engine light will not illuminate. I have a wire from the starter solenoid and I will hold that wire to the battery + side and this will crank over my engine every time. I replace start switch twice and then when through all the wires from the start switch and checked for damage or loose connections and nothing. The ignition rack assembly has been replaced as well too. I'm at my last string with this.

Bake315 - This weekend I went through all the wiring at the back fuse block and didn't see anything out of the ordinary. I"ll look again this coming weekend. Thanks

[bake315]

I have no power door lock or window power. Would the breaker still be needed?

The starter will crank the motor at first start. If I take a little trip and stop and then start again I will get no start. When this happens the starter will click one short time and the red engine light will not illuminate. I have a wire from the starter solenoid and I will hold that wire to the battery + side and this will crank over my engine every time. I replace start switch twice and then when through all the wires from the start switch and checked for damage or loose connections and nothing. The ignition rack assembly has been replaced as well too. I'm at my last string with this.

Bake315 - This weekend I went through all the wiring at the back fuse block and didn't see anything out of the ordinary. I"ll look again this coming weekend. Thanks

This may seem unrelated, but check thoroughly your major ground points, particularly the one from the battery to the front of the engine.  Not only the connection points, but also the strands within.  The "click and "nothing" symptom was one of the first things I dealt with on my '75.  Got me when I stopped halfway home for gas after buying it.  A $180 tow later, I was home.  Ended up picking up a 1-gauge battery to ground cable from Tractor Supply.  I haven't had the problem since (though I also replaced the starter in the process).

bake315

[bd]

Is a wire plugged into the cavity directly below the circuit breaker, that is, the cavity between the breaker and the flasher? 

If "No," then remove the breaker and check whether all of the electrical appliances work correctly.  If everything works as it should then you can remove the breaker.  However, if you leave it then you have a protected 30-amp power tap that is hot with the ignition switched on. 

If "Yes," the circuit breaker protects the circuit plugged into said cavity.


Make sure the starter is bolted tight to the block.  Verify that the battery cable connections to the battery and starter solenoid are clean and tight and that there is no evidence of hidden corrosion (e.g., localized swelling or stiffness) under the cable insulation near the cables' ends.  Inspect the battery cable connection to the starter solenoid for any visual evidence of burning or arcing.  If you have a voltmeter, measure the voltage between the battery negative post and the starter case while attempting to crank while the symptoms are active.  If you measure >0.3 volt while attempting to crank, disassemble and clean the ground cable connections to the battery and block or replace the battery ground cable using a 2- or heavier gauge all copper cable.  Measure the voltage at the starter solenoid "S" terminal when the no crank symptoms are active while attempting to start.  If the voltage measures >11 volts at the "S" terminal, the starter won't crank and the starter ground has been verified, replace the starter.

[Chuck Step-a-side]

Db, I did replaced the starter and installed a 3 gauge wire from Battery Neg to the engine block ground. I will follow through with the testing this weekend. Thank you, Chuck