FJ40 AMP gauge test (1 Viewer)

[Pin_Head]

You have a real mess there with lot of janky aftermarket wires installed improperly. Hard to say where your fusible link is, but it might be the POS with the blue tape on it.

Even the battery terminal is a POS. It says it right on it.

 

[Trollhole]

Pretty easy answer right there. The previous owner hated you.

The big fat new red wire. WHat wire is it spliced to in your harness. Willing to be it was where your fusable link was supposed to be.

 

[vt0u812]

I also wondered if the new red and black wire was where this was supposed to be. Seems i need to back up and do some rework to get this back in safe working order.
Thats said - all fuses are working so i guess im questioning if my amp gauge is dead? As i mentioned earlier - the needle sits dead nuts in the center and doesnt move under any load. Will this needle fall in one direction or the other if it were still in operating condition?

 

[Trollhole]

Yes. But what alternator do you have on your truck? Is it stock?

 

[vt0u812]

Its a good question Trollhole - mi betting its been replaced...let me look - ill post a pic

 

[vt0u812]

ok - here's the pic...definetly a replacement and now that i've looked closer im currious what the rogue male plug not connected to anything is.

 

[oldschool4wheeling]

Thats a stock set up. Looks like a new alternator though.

Not sure about rogue plug, but my 79 has one too.

 

[Ming89FJ62]

Here's how the wiring at the alternator should look

WB=White w/ Black trace
WL=White w/ Lavender trace
B=Black

 

[BreckenridgeCruiser]

I think that plug is a test lead to check alt output. If it is black/yellow then it follows Toyotas usage of that color for hot voltage. Mine was further upnon the firewall but looked the same...

Sent from my HTC One_M8

 

[Ming89FJ62]

looks like the PO used an internally regulated alternator instead of externally regulated.

 

[456z]

My 79's gauge never moved more than 1/2 a needles width and when I restored it was determined to make it work. Tracked the problem to dash circuit board amp inputs from wiring harness (both terminals) and one of the gauge to board connections. I chose to just solder the wiring harness inputs to the traces rather then cutting the rivets, cleaning up and re-riveting. Testing with a ohm meter will tell you if the connections are dirty.

 

[vt0u812]

All good thoughts - seems i have some work to do ...to diagnose what the hell the scope is here....

 

[Landpimp]

Pretty sure an Internal reguator is correct for a 79, US spec.

looks like the PO used an internally regulated alternator instead of externally regulated.

 

[Ian Macdonald]

My Frankenyota (Toyotastein??), being 1973, has a 30 amp ammeter. It now has a 100 amp alternator, no sensing wire connected, and no fusible link (all gifts from the PO). Am I in trouble here?

 

[Pin_Head]

My Frankenyota (Toyotastein??), being 1973, has a 30 amp ammeter. It now has a 100 amp alternator, no sensing wire connected, and no fusible link (all gifts from the PO). Am I in trouble here?

Probably not. The chances that the wire will ever see the full output of the alternator are slim, unless you have an electric winch. The wire can take 100 A for a few minutes, which is often enough to drop the charging current into the safe range on a fully discharged battery. It would still be a good idea to have a fusible link at the alternator to prevent the possibility of burning the harness wires.

 

[Mace]

Pin, even if he did have a electric winch, that would be connected directly to the battery and bypass the ammeter correct?

Never-mind, I thought about it a bit more.

 

[Pin_Head]

It is all about draining the battery and having to charge it up from zero.

There is also the unlikely possibility of getting a short circuit in the unfused power lead at the ignition switch or fuse block. This would pop the battery fusible link, but if the engine was running the alternator could put out enough power to burn up the harness, which is why I suggest installing a fusible link at the alternator.

 

[Ian Macdonald]

Thanks for the good advice. Fusible link tops my todo list. My LOOOOOONG todo list