Notices

HOW TO: Swap AMP meter to VOLT meter

 
  #1  
Old 10-06-2014, 01:24 PM
JimsRebel's Avatar
JimsRebel
JimsRebel is offline
Posting Guru
Thread Starter
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.
HOW TO: Swap AMP meter to VOLT meter

You can buy the Volt Meter from “Rocketman's Classic Cougar Innovations” for $45

Rocketman's Classic Cougar Innovations


So all you have to really do is remove the Amp Meter and install the Volt Meter into the instrument cluster. The original Amp Meter wiring has hot power on both terminals and thus will not work at this point. A Volt meter needs power and ground. I choose to use the truck's original wiring to do this instead of altering or modifying the circuit film on the back of the instrument cluster.

The original amp meter wiring is located near the battery. The minimum wiring changes needed are cutting and grounding one wire under the hood as shown in the attached photos. The wire you cut is the SMALL yellow wire not the big yellow one. Strip the firewall side of the small yellow wire (cap the other end) and jumper to ground. That's it. Now check out your new Volt Meter; i'ts reading Battery Voltage.

Well you might have noticed that you never turned ON the key switch. The original Amp Meter wiring was Hot all the time, powered off a fusible link. The new Volt Meter draws 68mA (.068 amps) of parasitic battery drain. While that might be OK for a new car these day, I don't think it's a good idea for trucks that are not driven frequently, so if you agree go on to Step 2.

Step 2
Find the small red wire that is right next to the small yellow one you just cut. The red wire is supplying the Hot Power to the volt meter. You will need to cut the red wire and feed Switched Key ON power into the Firewall side of the red wire. Be sure to cap engine side of these wires as they are hot all the time. For my KEY ON power I used an extra power wire I had left over from my DS2 conversion.

So now to recap...
The firewall side of the small red wire is now the positive feed point for the new voltmeter and firewall side of the small yellow one is now the voltmeter ground. Be sure to cap off the engine side of these wires you cut as there is still hot power there.


Reasons to do the swap:
The Amp Meter needle deflection is so small that it is nearly impossible to tell when the Alternator has failed, even at night with the lights on you will only see about a needle's width of movement toward the discharge side.
3G Alternator swap. The Amp Meter no longer works due to bypassing the Shunt Wire with larger gauge wire.


Safety stuff...
Removing the Battery Negative terminal while doing wiring on your truck will prevent bad things from happening.
While on the safety topic, it would also be a good idea to buy an inline fuse holder with a one amp fuse installed in it and use this as the jumper wire to ground, or in the power supply side. Point being that if anyone else at a later time did reinstall a stock instrument cluster with an amp meter, the fuse would protect the wiring and amp meter from smoking. The original amp meter wiring was not fused or protected.


This “How To” is a work in progress. Please feel free to add info and/or links with additional info, like how to R and R the instrument cluster or what source you used for Key ON power.

The following posts will have the photos with captions for a step by step installation.

Jim
 
  #2  
Old 10-06-2014, 01:30 PM
JimsRebel's Avatar
JimsRebel
JimsRebel is offline
Posting Guru
Thread Starter
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.
The first photos deal with finding the yellow wire which is the new ground wire.










 
  #3  
Old 10-06-2014, 01:37 PM
JimsRebel's Avatar
JimsRebel
JimsRebel is offline
Posting Guru
Thread Starter
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.
These photos are for Step 2, the red wire.
Voltmeter input positive voltage

.




 
  #4  
Old 10-06-2014, 01:47 PM
JimsRebel's Avatar
JimsRebel
JimsRebel is offline
Posting Guru
Thread Starter
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.
Here are some photos of the new voltmeter. You should repaint all the needles to match the new voltmeter
.






Bob can provide the paint for the needles which will save on shipping cost.
I use HP-FLRED pointer paint from HiPo Parts for the factory look.
or
Testors Model Master Fluorescent Red FS28915 for the 'aged' look.
Both come in small bottles
 
  #5  
Old 10-06-2014, 01:51 PM
ctubutis's Avatar
ctubutis
ctubutis is offline
Moderator
Join Date: Nov 2007
Location: Denver Metro Area, CO
Posts: 21,690
ctubutis has a superb reputationctubutis has a superb reputationctubutis has a superb reputationctubutis has a superb reputationctubutis has a superb reputationctubutis has a superb reputationctubutis has a superb reputationctubutis has a superb reputationctubutis has a superb reputationctubutis has a superb reputationctubutis has a superb reputation
Thanks, Jim!

Moved to HOWTOs subforum....
 
  #6  
Old 10-06-2014, 01:55 PM
JimsRebel's Avatar
JimsRebel
JimsRebel is offline
Posting Guru
Thread Starter
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.
Here are some links with good info.

Info on the wiring connector, pin out / wire colors, on the back of the instrument cluster.
https://www.ford-trucks.com/forums/1...l#post14682638

Photos of the voltmeter with different voltage inputs.
https://www.ford-trucks.com/forums/1...l#post14111829

Photos of the back side with the Amp meter removed.
https://www.ford-trucks.com/forums/1...l#post14709936
 
  #7  
Old 10-06-2014, 02:58 PM
JimsRebel's Avatar
JimsRebel
JimsRebel is offline
Posting Guru
Thread Starter
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.
Here is some info on bench checking the voltmeter before I installed. My trucks 3G ALT runs about 14.5 volts give or take a little, depending on if the lights are on. The stock 2G was a lot lower voltage.
.

 
  #8  
Old 10-08-2014, 04:22 AM
ArdWrknTrk
ArdWrknTrk is offline
pedant
Join Date: Jan 2008
Location: EXTREME southwest CT
Posts: 23,573
ArdWrknTrk has a superb reputationArdWrknTrk has a superb reputationArdWrknTrk has a superb reputationArdWrknTrk has a superb reputationArdWrknTrk has a superb reputationArdWrknTrk has a superb reputationArdWrknTrk has a superb reputationArdWrknTrk has a superb reputationArdWrknTrk has a superb reputationArdWrknTrk has a superb reputationArdWrknTrk has a superb reputation
This is a great writeup Jim!
Rep's were denied.

I think I introduced Gary Lewis to the Rocketman site.
He has documented the results of his conversion.

I have a stock voltmeter in my '87 and found that putting the headlight relay harness and a blower relay in, resulted in much more stable cab (dash) voltages.

What's the ground path?
I have two new cab seam to frame ground straps and a good cable from the wiper motor to the back of my intake.
My 3G setpoint is 14.35V.
I see that at the battery but not in the cab.
Most of the load is off so shouldn't the voltage throughout the truck be the same?
 
  #9  
Old 10-08-2014, 05:04 PM
JimsRebel's Avatar
JimsRebel
JimsRebel is offline
Posting Guru
Thread Starter
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.
The Voltmeter is grounded to one of the bolts on the starter solenoid.
The voltage should be reasonably stable and consistent until you add load. I also have headlight relays. I notice my biggest fluctuations on the new voltmeter when I turn my fan on high as my voltage is being read off the fuse block somewhere.

The set point for the voltage regulator is based on where the yellow wire is connected to.
Most just jumper this wire to the main ALT output stud on a 3G swap. So in a sense, the ALT is it own reference point. Ford ran the yellow wire to the far side of the ALT shunt wire. This slight amount of resistance in the shunt wire coupled with the dampening effects of being closer to the battery helps create a much more stable reference point.

Attached is a photo showing a schematic for a stock Amp meter and where the yellow wire is connected to. Also there is a drawing of the stock amp meter current divider with resistance values.
Jim

.
 
  #10  
Old 10-08-2014, 06:44 PM
ArdWrknTrk
ArdWrknTrk is offline
pedant
Join Date: Jan 2008
Location: EXTREME southwest CT
Posts: 23,573
ArdWrknTrk has a superb reputationArdWrknTrk has a superb reputationArdWrknTrk has a superb reputationArdWrknTrk has a superb reputationArdWrknTrk has a superb reputationArdWrknTrk has a superb reputationArdWrknTrk has a superb reputationArdWrknTrk has a superb reputationArdWrknTrk has a superb reputationArdWrknTrk has a superb reputationArdWrknTrk has a superb reputation
3G regualtors are available in various set points.
I happen to have a white LRC regulator set for 14.35V.
The cabling and such provides no drop to the relay and battery.

I don't see anything grounded at the relay mounting screws.
The cab is well grounded (I think...)
Just not sure if my voltage drop is in the ignitin switch, fuse panel or the cluster itself.

Thanks for the explanation!
 
  #11  
Old 10-25-2014, 08:08 PM
theguruat12's Avatar
theguruat12
theguruat12 is offline
Junior User
Join Date: Aug 2013
Location: Tucson, AZ
Posts: 59
theguruat12 is starting off with a positive reputation.
Good write-up, I don't know if linking to OB violates FTE's policies, but I actually did a write up on this as well last year over there. I have some pictures of the actual swapping of gauge guts into the old housing.

Ammeter to Voltmeter Conversion
 
  #12  
Old 10-25-2014, 08:43 PM
ctubutis's Avatar
ctubutis
ctubutis is offline
Moderator
Join Date: Nov 2007
Location: Denver Metro Area, CO
Posts: 21,690
ctubutis has a superb reputationctubutis has a superb reputationctubutis has a superb reputationctubutis has a superb reputationctubutis has a superb reputationctubutis has a superb reputationctubutis has a superb reputationctubutis has a superb reputationctubutis has a superb reputationctubutis has a superb reputationctubutis has a superb reputation
Originally Posted by theguruat12 View Post
Good write-up, I don't know if linking to OB violates FTE's policies, but I actually did a write up on this as well last year over there. I have some pictures of the actual swapping of gauge guts into the old housing.

Ammeter to Voltmeter Conversion
No, not at all. And thank you.
 
 
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
rechinca
1967 - 1972 F-100 & Larger F-Series Trucks
29
03-04-2017 06:12 AM
Montync
1980 - 1986 Bullnose F100, F150 & Larger F-Series Trucks
4
03-02-2017 12:33 PM
roots4thought
1987 - 1996 F150 & Larger F-Series Trucks
9
05-19-2016 01:59 PM
brad1979
1980 - 1986 Bullnose F100, F150 & Larger F-Series Trucks
2
10-16-2015 06:25 AM
old broke prospector
1961 - 1966 F-100 & Larger F-Series Trucks
0
04-09-2013 07:43 AM


Thread Tools
Search this Thread
Quick Reply: HOW TO: Swap AMP meter to VOLT meter


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.
 
  • Ask a Question
    Get answers from community experts
Question Title:
Description:
Your question will be posted in: