Amp Gauge Wierdness (1 Viewer)

[Horsehead]

Here's my problem... My Amp Gauge (stock) reads at about the negative 30 mark when I drive at night (headlights, turn signals, electric fan, etc.) when I have the turn signals on, the amp gauge bounces down bellow the neg. 30 mark and back up in rythm with the signal... I have a brand new alternator and I don't think that's the problem. The only new electical part is a DUI HEI Distributor from ManAFre... Any thoughts or suggestions would be greatly appreciated.

 

[busiboy]

I have a similar prob, except I run a SBC.

My probelms started when I put the electric fan in (made a few other mods that made it necacary). If you run the stock alt and a Thermo fan the orig alt isn't big enough to power it.

The orig is only 35 amps, I am about to replace with an 80amp odd alternator.

hope it helps
Scott

 

[Pin_Head]

There are a couple of possibilities. The obvious one is the alternator isn't working, but by now the battery would be dead. The other one is that the alternator is wired directly to the battery (or the battery side of the alternator). That way the amp meter will only indicate the chassis current. Normally it is wired to the chassis side of the amp meter (the meter is in between the battery and the chassis), so that it indicates current in and out of the battery.

 

[MrMoMo]

Yup, sounds like you are only reading the loads coming off the battery, but not the charging current going in. (using 30 to 35 amps, but must be charging at a minimum of 30 to 35 amps or your battery would slowly go flat)

If you can find someone with a DC Amp clamp meter, get them to clamp it on the wire coming from your alternator. Run the engine and turn on your lights etc.. read the flow of current from your alternator to your battery, this should give you a better idea of what is going on.

 

[Rick '79 FJ40]

I don't know about your particular vehicle, but mine has 2 fuses under the hood on the wiring harness near the coil/ignitor that are for the ammeter. You could have blown one of these fuses, the one for the alternator side of the ammeter. Check for a small (approx. 3"x3/4"x1/4") black plastic snap together fuse holder. Seems like they are 5 amp fuses IIRC.

Hope this helps.

 

[Pin_Head]

Only later curisers (79 and up) have the two fuses for the amp meter. They also use the fusiblew link as an "external shunt", so if one of the fuses blow, the meter won't work and there is a problem with the fusible link.

 

[Horsehead]

so the question now is, what's supposed to be wired to where? Also, where is everything grounded to? could it be bad grounding causing problems

 

[Pin_Head]

so the question now is, what's supposed to be wired to where? Also, where is everything grounded to? could it be bad grounding causing problems

Stock alternator? It should be wired directly via a large gauge white wire with blue stripe to the amp meter in your dash. The other side of the amp meter has a large white wire that goes directly to the battery. The chassis wiring connects to the alternator side of the meter.

The alternator is gounded to the engine and frame, just like the battery. What's the problem? How is the alternator B+ terminal wired up now?