1984 Instrument cluster wire always hot?

['84-460-Project]

I have my instrument panel out, battery connected and no key in the ignition. Just for kicks I broke out the test light and started checking each circuit on the main connector for the instrument panel.

Circuit 8 (654) Yellow/Green and 9 (655) Red and Orange are hot (in this case - always hot). Looking at the 1986 EVTM pg 15 these circuits feed the ammeter on the instrument cluster. I've never seen this working (one of the reasons I have the cluster out).

Are these circuits always hot, or do I have an issue with one of my connections?

Thanks

[Gary Lewis]

Yes, those circuits are always hot.  As you can see in the schematic below, which is from the '85 EVTM but should be the same as the '86 one, the red/orange connects to the always-hot side of the starter relay, which is also where the shunt connects.  And the yellow/green connects to the other end of the shunt, and that's always hot as well.

So the ammeter is watching the current flow across the shunt.  If it flows from the battery to the right, meaning towards the truck, then it shows a discharge.  But if is flows from the alternator toward the battery, meaning the the left, then it shows a charge.

A test for the ammeter is to turn the headlights on w/o starting the truck.  The ammeter should show a discharge.

['84-460-Project]

Gary, thanks so much. This site is an outstanding resource and is consistently proving its value.

I freakedout out a little when I went to reinstall the instrument cluster and one of the "hot" circuits made contact and a little smoke came out. Hopefully it didn't do to much damage.

Lesson learned - disconnect the neg terminal when reinstalling the instrument panel.

[Gary Lewis]

Glad the site is helping.

Sure hope you didn't let too much smoke out of your wiring.  

[Steve83]

'84-460-Project wrote

...the ammeter on the instrument cluster. I've never seen this working (one of the reasons I have the cluster out).

They never worked - even new.  That's one reason Ford (& every other automaker) switched to a voltmeter.  It's relatively easy to swap one in, and it will be much more-useful to you.  This shows my heavily-modified cluster, but focus on the voltmeter in it & the NEXT pic:

[Rembrant]

Steve83 wrote

 That's one reason Ford (& every other automaker) switched to a voltmeter.  It's relatively easy to swap one in, and it will be much more-useful...

Steve,

What Voltmeter did you swap in there? One from a Bricknose? Do you have a write-up on that somewhere?

[Steve83]

Rembrant wrote

What Voltmeter did you swap in there? One from a Bricknose?

Possibly, but more likely '92-96.  The guts of the meter are probably the same - only the face might be slightly different.

Rembrant wrote

Do you have a write-up on that somewhere?

Not on that exact cluster, but the concept & process is very similar to what's shown in this, the NEXT several pics, and the links in the captions:



Only the '80-86 ammeter is easier because it's not full-current, so you don't have to worry with the big ammeter wire - just abandon the 2 small ones (because they're always-hot, and you don't need the voltmeter on all the time), and add a jumper from the switched-hot on the cluster to the new meter, and another from the new meter to cluster return (ground).

You'll probably use the original ammeter face, and just learn where the voltmeter needle sits (because it would be difficult & expensive to 3D-print a new plastic face with volt markings).

[kramttocs]

The gentleman at Rocketmans is great to work with. I had him convert mine.

https://www.ford-trucks.com/forums/1339746-how-to-swap-amp-meter-to-volt-meter.html

[Gary Lewis]

kramttocs wrote

The gentleman at Rocketmans is great to work with. I had him convert mine.

https://www.ford-trucks.com/forums/1339746-how-to-swap-amp-meter-to-volt-meter.html

Yes, he is.  He did mine as well.  And since I'll use that on Big Blue I'll have to have him do another for Dad's truck.

[grumpin]

Thought I’d show y’all the high falutin’ gauge I installed!

[Gary Lewis]

I have something like that laying around here somewhere.  But as the cigar lighter is always on, mine was always drawing current.  Perhaps it isn't enough to be a problem?

[grumpin]

I only put it in when I want to see what’s going on.

[Gary Lewis]

Good plan, Stan.