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ray_mcavoy · 01-26-2018, 05:44 PM

Yes, they had one or the other but not both.

Trucks with the basic warning light style cluster had a "GEN" or "BATT" light wired to the alternator.

Trucks with the factory gauge clusters had a special resistance wire (in the cab / dash harness) to take the place of the warning light. And used a voltmeter (or ammeter in earlier years) to monitor the charging system.

The built-in factory resistance wire is only about 10Ω and the CS series alternators require a minimum of 35Ω in the circuit connected to their "L" terminal. So you'll want to add some additional resistance. I believe there are some plug conversion adapters available with a built-in resistor specifically for this purpose.

01-26-2018, 05:44 PM	#2
ray_mcavoy Registered User Join Date: Nov 2009 Location: Sherman, ME Posts: 2,354	Re: Idiot ? Light that is... Yes, they had one or the other but not both. Trucks with the basic warning light style cluster had a "GEN" or "BATT" light wired to the alternator. Trucks with the factory gauge clusters had a special resistance wire (in the cab / dash harness) to take the place of the warning light. And used a voltmeter (or ammeter in earlier years) to monitor the charging system. The built-in factory resistance wire is only about 10Ω and the CS series alternators require a minimum of 35Ω in the circuit connected to their "L" terminal. So you'll want to add some additional resistance. I believe there are some plug conversion adapters available with a built-in resistor specifically for this purpose.