Ammeter Spaz Out (1 Viewer)

[MyCruiserisaHogBeast]

I have what may be a dumb question: I was going through my checklist of to do's and I remembered that a few months ago I was driving and my ammeter needle started bouncing all over the place, then died. Alternator is newish. The truck runs fine, everything works, batteries charge. No burning smells. I looked around a bit and couldn't find anything, then I totally forgot to look into it more as my truck didn't get driven too much before I took it to the spa because it was a stinky old hag that needed some refreshing. It's going to be a couple of weeks before it's fired back up again, but when it does what should I look for? Is this likely a gauge issue or a short somewhere? Anyone else experienced this? It looks like I'm going to get some new gauges, mine are pretty hammered after getting some sand in them when I had the tub sandblasted (don't ever trust someone who is giving you a "good deal" and says it will be fine....). I just don't want to stick a fancy new cluster in there and have some other problem blow a gauge up.

If anyone has any insight it would just be something to write down when I go through my checklist. Thanks guys.

 

[unklwedy]

Search for voltage regulator on this site. Napa has an eletronic VR that should fix yer problem forever.

 

[Pin_Head]

'78 or later amp meter? If so, the meter fuses have blown because you have a bad fusible link.

 

[DougAustinTx]

I would join the two leads together if it was '78 or earlier and install a voltage gauge instead.

 

[MyCruiserisaHogBeast]

'78 or later amp meter? If so, the meter fuses have blown because you have a bad fusible link.

Yeah, '79. So you think I blew a fuse? Funny, I didn't even think to look there. Before I throw a new cluster in there is there something I should look into as to the cause of the of the fuse popping in the first place? When I dug around I didn't see any problems. Thanks for the reply.

 

[Pin_Head]

Yes. The post '78 meter uses the fusible link as an external shunt and the meter leads are fused with 1 amp fuses to protect the meter. When the fusible link connections get corroded, this sends more current through the meter, blowing the fuse or fuses. You need to replace the fusible link or clean up its connections or you will just keep blowing fuses. The fuses are in a fuse holder box taped to the wire harness a few inches away from the fusible link, which is attached to the + battery post.

 

[Landpimp]

I am just shocked your 79 amp meter ever moved at all......never seen one move on 81+(79-80 similar), I think Marv commented once about the same thing

I made a new link for my 82, meter never moved before or after

 

[Pin_Head]

Unfortunately, the normal operation of the amp meter is also the way it behaves when it is broken. If you discharge the battery enough, like by winching or engine cranking for several minutes, it should deflect positive by at least the rated output of the amp meter for a few minutes until the battery charges back up. If it doesn't deflect at all, it may be broken. You should also see it negative by turning on all the lights and flashers when the engine is off.

 

[bj40green]

This is your fuse box for the Ammeter. Picture from Lostmarbles.

If you replace your fusible link with this construction, you'll have a working Ammeter. Thanks to Amaurer.

18" of coiled 14ga wire inserted in the fusible link looks like this picture:

This is a fusible link for a Diesel. For a FJ it will look a bit different.

More info here: -► https://forum.ih8mud.com/threads/clusters-gauges-speedo-odo-meters.544543/page-16

Rudi

 

[MyCruiserisaHogBeast]

This is your fuse box for the Ammeter. Picture from Lostmarbles.
View attachment 1040071

If you replace your fusible link with this construction, you'll have a working Ammeter. Thanks to Amaurer.
View attachment 1040069

18" of coiled 14ga wire inserted in the fusible link looks like this picture:
View attachment 1040116

This is a fusible link for a Diesel. For a FJ it will look a bit different.

More info here: -► https://forum.ih8mud.com/threads/clusters-gauges-speedo-odo-meters.544543/page-16

Rudi

I love lightbulb moments!!!! I know where this thing is and I always wondered what it is! Awesome thanks guys!

 

[MyCruiserisaHogBeast]

Unfortunately, the normal operation of the amp meter is also the way it behaves when it is broken. If you discharge the battery enough, like by winching or engine cranking for several minutes, it should deflect positive by at least the rated output of the amp meter for a few minutes until the battery charges back up. If it doesn't deflect at all, it may be broken. You should also see it negative by turning on all the lights and flashers when the engine is off.[/QUOTE

It worked up to this point, but it bounced around for about 30 seconds before stopping. I think I know the culprit now thanks to you and Rudi.

 

[Landpimp]

very interesting. So the 18" length is making a certain resistance or something?

I had to rebuild(it was burned when I got it) my link when I 1st got the 82, I made it the same(length/gauge) as the one I removed. The amp meter did not move before, nor did it move after. (all my 78 and earlier amp meters work as they should)

I am not seeing how this works or why? (but I am sure they is a reason)

 

[bj40green]

very interesting. So the 18" length is making a certain resistance or something?

I had to rebuild(it was burned when I got it) my link when I 1st got the 82, I made it the same(length/gauge) as the one I removed. The amp meter did not move before, nor did it move after. (all my 78 and earlier amp meters work as they should)

I am not seeing how this works or why? (but I am sure they is a reason)

Cruisers till end '78 have a 30-0-30 Ammeter which is directly in series between alternator and battery.
Cruisers '79 and later have 50-0-50 Ammeter which works with a shunt resistor. Mr. Toyota used the fusible link as a shunt but it was bad designed and it NEVER worked on any 40 series Cruiser.
Did you read the link that I posted earlier? From there go back to page 4 posting #78 and you get the whole story how we (mainly Amaurer) figured this out.

Rudi