'66 Mustang GT - Constant Voltage Unit - MustangForums.com

Classic Mustangs (Tech) Technical discussions about the Mustangs of yester-year.

Thread Tools Search this Thread
Old 03-09-2018, 12:14 PM   #1  
Thread Starter
Join Date: Aug 2012
Location: Florida
Posts: 4
Default '66 Mustang GT - Constant Voltage Unit

Having difficulty getting y gauges and dash lights to work - anyone know how to check the "Constant Voltage Unit" to see if it's OK?
Signtist is offline   Reply With Quote
Old 03-09-2018, 01:09 PM   #2  
4th Gear Member
Join Date: Jan 2018
Location: Pennsylvania
Posts: 1,151

With a volt meter. Just check for +5 Vdc on the output side of it.

It is a regulator, changes the input 12V to 5V for the cluster. When it goes bad,
all your gauges will give erroneous readings except the fuel gauge; and ampmeter
if equipped.

Sample 5Vdc Regulator:

10.0ĶF 50V Axial-Lead Non-Polarized Capacitors.
+5V Fixed-Voltage Regulator 7805.

It puts out a constant 4.98 volts DC all the way up to a 1 amp load.
Put an inline fuse (2 amps) in the circuit in case there is a short.

A new unit will be like $26.00+ on-line. That diagram is in case you want to build your own
and put it inside the shell of the old one. Heat shrink tube all the leads...Voltage Regulator Circuit; 12V to 5V for older mustang gauge clusters.
08'MustangDude is online now   Reply With Quote
Old 03-11-2018, 12:54 PM   #3  
Thread Starter
Join Date: Aug 2012
Location: Florida
Posts: 4
Default CVU problem

Mustang Dude...thanks 4 the reply & diagram...and yes, fuel gauge and ammeter work and they others don't - HAS 2 BE the answer...getting a new CVU
Signtist is offline   Reply With Quote
Old 03-13-2018, 09:52 AM   #4  
2nd Gear Member
Join Date: Apr 2014
Location: PA
Posts: 404

The fuel gauge runs off the voltage regulator along with the oil pressure gauge and the temperature gauge. Unfortunately the wires are all Blk-Green. Make sure it is connected correctly. The Wire from the big connector under the dash (12V positive) is by itself. There are two wires on the other side.
bop11 is offline   Reply With Quote

Related Topics
Thread Thread Starter Forum Replies Last Post
2007 V6 manual Mustang constant buzzing ***Kristie*** General Tech 4 10-23-2014 07:16 AM
Constant Hum/High Pitch sound from my 94 Mustang front Right Wheel peetah2 General Tech 3 09-26-2006 12:57 PM
Constant Control Relay Module (CCRM) Pantera5.0 5.0L (1979-1995) Mustang 1 02-25-2006 07:41 PM
1965 Mustang--Need Constant 12V Source JDBlewett Classic Mustangs (Tech) 1 09-13-2005 07:13 PM
65 Voltage Unit Removal? Surferdude617 Classic Mustangs (Tech) 1 08-02-2004 11:07 AM

constant voltage unit

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Forum Jump

Featured Sponsors
Vendor Directory

All times are GMT -5. The time now is 05:06 PM.

© 2018 MH Sub I, LLC dba Internet Brands
We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.