Notices
1980 - 1986 Bullnose F100, F150 & Larger F-Series Trucks Discuss the Early Eighties Bullnose Ford Truck

Voltage gauge, Need help

 
  #1  
Old 03-01-2017, 03:34 PM
Montync's Avatar
Montync
Montync is offline
Senior User
Thread Starter
Join Date: Oct 2015
Location: Franklinton, NC
Posts: 283
Montync is starting off with a positive reputation.
Voltage gauge, Need help

So my 1984 f150 had idiot lights, I switched to a digital dash. I dont like the wiring and had fears of a fire so I am looking for Deutsch connectors. Until then I put in a dash that has gauges for all (fuel,oil,temp,batt)

The issue and I dont know if this is normal:

With the key on no cranking, my gauge pegs out at "C"
with the Key off It goes in the middle of "D" and "C"

Now with the digital guage it will read 11.9 at the battery (Fuel pump priming)
with this cluster and a volt meter it reads 12.1 at the battery

With the cluster unplugged I get 12.53 at the battery

I cannot crank it as the distributor is out.

Is it suppose to peg out to c before cranking?

Why the .43 voltage drop?

testing the cluster wires for continuity to ground (Key off) I got the following tone hits:

Black:Ground
Blue Red: Instrument Lights
Red green: Ignition switch
Red Yellow: Cigar lighter
White Blue: Right Turn signal
Green /Light green: Seat belt warning buzzer.

Can someone guide me?
Thanks
 
  #2  
Old 03-01-2017, 04:38 PM
Montync's Avatar
Montync
Montync is offline
Senior User
Thread Starter
Join Date: Oct 2015
Location: Franklinton, NC
Posts: 283
Montync is starting off with a positive reputation.
I have traced the drop to the following wires. The green red wire (excites the alternator) and white blue.

Key on volts read 12.1 with everything hooked up
When the green/red wire is removed (key on) the voltage is 12.32
Key off 12.55

with green red and white blue removed it reads 12.48

The alternator is a 3g alternator. Is it suppose to have that much of a drop?
How is the white blue causing the drop (faulty multifunction switch?)
 
  #3  
Old 03-01-2017, 07:00 PM
Montync's Avatar
Montync
Montync is offline
Senior User
Thread Starter
Join Date: Oct 2015
Location: Franklinton, NC
Posts: 283
Montync is starting off with a positive reputation.
Guage pegs because I have an anmeter and a 3g alternator.. Wish there was a way to get it to work like a volt meter.
 
  #4  
Old 03-01-2017, 07:57 PM
JimsRebel's Avatar
JimsRebel
JimsRebel is offline
Posting Guru
Join Date: Mar 2008
Location: Washington
Posts: 1,658
JimsRebel has a great reputation on FTE.JimsRebel has a great reputation on FTE.JimsRebel has a great reputation on FTE.JimsRebel has a great reputation on FTE.
Originally Posted by Montync View Post
Guage pegs because I have an anmeter and a 3g alternator.. Wish there was a way to get it to work like a volt meter.
https://www.ford-trucks.com/forums/1...olt-meter.html

Jim
 
  #5  
Old 03-02-2017, 12:33 PM
Franklin2's Avatar
Franklin2
Franklin2 is offline
Moderator
Join Date: Jan 2001
Location: New Market, VA
Posts: 43,724
Franklin2 has a brilliant futureFranklin2 has a brilliant futureFranklin2 has a brilliant futureFranklin2 has a brilliant futureFranklin2 has a brilliant futureFranklin2 has a brilliant futureFranklin2 has a brilliant futureFranklin2 has a brilliant futureFranklin2 has a brilliant futureFranklin2 has a brilliant futureFranklin2 has a brilliant future
The green/red to the alternator tells the alternator regulator inside it(or outside it if you have the old type) to come "online" and get ready to charge. This puts voltage on the field windings which causes a draw on the battery. That's the reason for the key-on wire to the alternator, so when you turn the key off it doesn't drain the battery with the engine off.

Those voltages you are reading are what they call a "surface charge" on the battery, over and above 12 volts. Very easy to get rid of that and have it drop down when you put a small load on the battery. Don't worry about it unless you get much below 12v.
 
 
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
stirfrysteve
Ranger & B-Series
7
01-18-2018 03:42 PM
maddmatt02
1987 - 1996 F150 & Larger F-Series Trucks
9
12-04-2017 08:00 AM
frederic
1987 - 1996 F150 & Larger F-Series Trucks
37
04-15-2017 09:23 PM
brokeasajoke
Explorer, Sport Trac, Mountaineer & Aviator
7
03-15-2017 03:46 AM
Montync
1980 - 1986 Bullnose F100, F150 & Larger F-Series Trucks
10
01-26-2017 05:55 PM


Thread Tools
Search this Thread
Quick Reply: Voltage gauge, Need help


Contact Us - About Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

© 2019 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.