Voltage drop at ignition switch

[Darcy]

Tried this in electrical forum but no joy:

When I turn my ignition switch on, I get a .9 (~12.7v to 11.8v)volt drop without the engine running. This is measured from (-) straight to the battery and (+) at the terminal on starter switch. No load in the circuit other than the instrument cluster (standard gauges, nothing electronic) and whatever is in the engine compartment.


Is that a normal drop for the coil? Engine is a OMC Chevy 305. 1986.
If not, what might my culprit be?

And for what it is worth, SeaRay did an interesting wiring job on my boat.

Thanks!

 

[Gary H NC]

Re: Voltage drop at ignition switch

You should have a good strong 12 volts at the switch. Time to trace the power and ground.
Are the gauges and everything else at the helm acting normal?

 

[Darcy]

Re: Voltage drop at ignition switch

You should have a good strong 12 volts at the switch. Time to trace the power and ground.
Are the gauges and everything else at the helm acting normal?

Everything runs fine with the exception of trim gauge, but that's a bad sender, and the stereo drops out from the low volts (which is why I'm investigating)


All connections seem clean, and with the key in acc (no ignition power), volts stay in the 12.5 range.

 

[Gary H NC]

Re: Voltage drop at ignition switch

Check the power and ground going to the switch and look for any crimp type connectors. I have had them corrode inside the connector but it looked fine.

It sounds like a ground issue.Run a temporary ground from the battery up to the helm and see what happens.

 

[wanna-be]

Re: Voltage drop at ignition switch

Tried this in electrical forum but no joy:

When I turn my ignition switch on, I get a .9 (~12.7v to 11.8v)volt drop without the engine running. This is measured from (-) straight to the battery and (+) at the terminal on starter switch.

this maybe too obvious but have to ask...1)is there 12v to coil? 2)ck ground on coil 3) ck all fuses. sounds like a loose ground. also gound your lead on block not battery

 

[JustJason]

Re: Voltage drop at ignition switch

hook up the - end of your DMM to the B+ terminal(or power in on the keyswitch) hook up the + to the I (ignition) out, put your meter on milivolts and turn the key, anything over 250mv replace the keyswitch.

 

[wanna-be]

Re: Voltage drop at ignition switch

voltage drop across ignition system s/n be more than 3-4 volts. somewhere you've got corrosion.

 

[Darcy]

Re: Voltage drop at ignition switch

I think there is some confusion. Total drop is 9/10ths of a volt.

Should I still be concerned? If so, I will check all of the suggestions.




Thanks for all of the replies!

 

[wanna-be]

Re: Voltage drop at ignition switch

no, sounds normal