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Note: These are the notes of a novice back yard mechanic so please be advised that you are following them at your own risk!

The following Images are from my stock 1966 Chevy / Chevrolet C10 Truck and illustrate the replacement of my Voltage Regulator and Alternator. It also shows my fuse box.

This applies to Chevrolet 1960 through 1966 C10 and K10 and also 1960 through 1966 GMC Trucks


1966 Chevy C10 Voltage Regulator mounting and wiring (may apply to 1960 through 1966)


Make certain that the Voltage regulator (especially new solid state type that some say are better) are grounded before you connect the battery so you don't harm the Voltage Regulator. This picture shows the Voltage Regulators ground wire connected to frame under the Horn Relay.




Notice the empty bolt hole at the bottom of this picture that is from a piece of of body I removed that is held in place by about 5 each 9/16 bolts (two of the 5 are different so remember which place they were in). I easily removed this long body part to gain clear access to the Voltage Regulator mounting bolts - see image of part below.







Stock mounting used 'well nuts' which you will probably destroy removing the VR so plan on buying a pack of various size grommets for about four bucks. Buy some 2 inch bolts, lock washers, and nuts also. There are three mounting holes. The Grommets are used to limit the vibration so do not use metal to metal mounts. Also see above for how the Voltage Regulator is grounded properly.



Looking down on the Voltage Regulator Connector you should see wires colored: Blue - White - Red and Brown

  • The Blue goes to the Alternator Field (marked 'F' on Alternator) via the wiring harness
  • The White goes to the Alternator Rotor (marked 'R' on Alternator) via the harness
  • The Red Goes to the Wiring Harness and has continuity to the Battery positive (disconnect battery positive before measuring)
  • The Brown goes to the Ignition via the harness and will have continuity to Battery Positive (disconnect battery positive before measuring) only with the Key in the 'On' or 'Start' Position (This basically turns the VR on and off so the battery does not drain when the key is off)

Note that when my VR went bad, a click noise could be heard when connecting or disconnecting the battery even with the key off. Also see next picture for the tab that you push down on to remove this Voltage Regulator Connector.


The VR will have one connector for each of the four wires and each of these four will be labeled with 'F' - '2' - '3' - '4' where the 'F' is for the Blue Field wire and the rest will follow. The connector and VR both have a key to insure the connection is plugged in properly. When you plug the connector in, make sure that it is held in place by the tab that is shown and told about above (next to Red wire). When disconnectiong, see more information below.





See that the connector (right next to the VR) that is aligned with the Red wire (3rd from front) has a small tab that must be depressed to remove the connector. Under the VR connection there is a small notch that looks like it's there to make sure the male (that has a key that aligns with it too) is compatible with the new or old VR.



See the 'Radio Static Eliminator condenser' (round under thumb) that I have read is not needed for radios made in the last 10 to 20 years. I cleaned mine up and used it to keep my vehicle original as possible. The condenser has a lead that is made to plug into a connector at the bottom of the VR. The condenser has printed on the top the following: 1960957 - DR - 6 MP -



View of the new Voltage Regulator that is now installed. Tthis is a digital VR which is now one of the few things that is not original on this Truck. Original equipment can get up in the neighborhood of $80.00.




1966 Chevy C10 Alternator wiring



Shows main positive connection



Shows the two smaller connections left of the main positive where the black is the field marked 'F' and note that this will have continuity to the blue wire on the VR connector (disconnect battery positive first before measuring). The Red wire is the Rotor marked 'R' on the back of the Alternator and note that this must have continuity to the white wire on the VR connector.






Above shows the back of the Alternator where the Field - marked 'F' and the Rotor - marked 'R' have connectors. See the 'F' and 'R' in the image


Please see the end of this page for step-by-step voltage regulator replacement instruction, final notes, and how to test your voltage regulator



1966 Chevy C10 Fuse Box - Various pictures of the same box














Click here to see another site's picture that shows the heater fuse placement above the Radio fuse.

Note that I have read that there is a mounting screw under one of the fuses




Final Notes


  • Disconnect Battery before measuring or doing work
  • Take pictures or record the placement of wires before disconnecting
  • Remove the front body part to gain access to the VR mounting bolts
  • Remove the two bolts holding the Windshield Washer Fluid holder
  • Use Grommets when mounting the VR to eliminate vibration
  • Use the stock wire from the VR to the Horn Relay mount to ground the VR
  • Make sure the VR is grounded before finishing up and connecting the battery or you could damage the VR
  • My Alternator only cost $50.00 at a local parts store and came with a warrantee (probably because it has no internal diodes)
  • The VR was purchased on Ebay for $16.00. It is a solid state and there are probably few people alive that can repair the old point style. It looks like Ebay has the old point style available for around $70.00 dollars. High electrical impulses can take out a solid state model which means when no vehicles can run, this vehicle won't either. The solid state VR may be the only electronic part in the vehicle.
  • The mounting Grommets and hardware was less than $7.00 dollars
  • Use blue lock tight on Voltage Regulator mounting nuts
  • To mount the new VR (three bolts), I secured a Grommet in the sheet metal, then one smaller grommet on each side of that (over bolt), then a lock washer on both sides, and then a nut with blue lock tight on the front side of sheet metal, however, you may want to switch things around, placing the nuts on the inside of the engine compartment and then the bolt screw heads on the front which would make for easier R and R and a better show car look (show cars should use original well nuts but make concider the length of them carefully
  • To Test your new Electrical System follow these steps:
    • Charge battery
    • Connect battery
    • Test for 12.5 Volts
    • Turn on lights and other accessories to drain any surface charge
    • Test for 12.5 Volts again and if yes continue
    • Test again now that the battery is connected to insure the VR is grounded
    • Check the following:
      • VR is mounted properly
      • VR connector is plugged in
      • Insure VR is grounded
      • Insure Alternator is secured to Engine
      • Insure Alternator Connections are correct and made solid (look from behind to insure you are plugging them into the connectors, not inbetween the connectors
      • Insure the fan belt is in place and tightened correctly
    • Remove tools and body parts from Engine compartment to prepare for starting
    • Start your Chevy C10 truck
    • Test the Voltage across the Battery while the Truck is running and look for 13 to 14.5 Volts (this varies so please research for yourself) and if yes you have the proper Voltage then continue - Or - you have a problem so recheck all connections, re-run continuity tests, and if still no proper Voltage take the Alternator and VR to have them tested by a professional
    • Run the Engine up about 2,000 and make sure the Battery Voltage does not exceed 14.5 (this varies so please research for yourself) Volts
    • See the Ammeter inside the cab as you run up the engine. After my system was rebuilt I never saw the meter go below the middle point and it did go above the middle until it got the battery built up well. Once the battery is build up, I never saw it go above the middle even with the lights and heater fan running. You could disconnect the main coil secondary wire and turn your starter over for less than a minute (don't over heat it) to drain the battery enough to then see the ammeter show a charge right after it starts.
    • Replace any body parts you have removed to gain access to the VR and Alternator
    • After you have had your vehicle on the road, come back to insure the VR and Alternator are still mounted securely

Please remember that I am not a professional mechanic and cannot guarantee this information as safe or accurate.



Here is a forum where someone explains how to convert your external Voltage Regulator to an internal. I don't know if it is correct

Convert external Voltage Regulator to internal Voltage Regulator for Chevy Trucks



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