RA28 Ammeter wiring help

[Paxman]

Hi again!

I'm sorry but I need to ask one more question about this.

With the 16 AWG-wire connected the way that makes the ammeter work doesn't it mean that all the current the car uses goes through the 16 AWG wire? (Except for the starter of course.) Will it really cope with that without burning? One chart I found rated 16 AWG wires under 4 amps which ought to be far less than the normal consumption of the car...

[andrewzuku]

We really need an auto-electrician to chime in here. I'm by no means an expert.

As I understand it, the two 16AWG lengths are running in parallel to each other. The different lengths split the current at a ratio of around 49:1.

98% of the current goes through the shorter 16AWG wire (approx. 100mm - effectively a fusable link), while the remaining 2% goes through the longer 16AWG wire (approx. 4900mm to the gauge and back).

The choice to use 16AWG was made a while ago, and I can't really remember which charts I looked up. I haven't had a problem with it though. I'll run my car again soon and see If I can use an IR gun to measure how hot it's getting.

[Paxman]

That would be great! As soon I get my car running again I'll do the same so we can compare the numbers. I got concerned when I noticed that the fuse and fuse holder I put between the fusible link and the white main lead got super hot when I did a load test on the battery. I put the fuse there to secure the 16 AWG wire and I have noticed that I need a 40 amp fuse, lower than that will blow under load.

[Paxman]

Today I bought new 10 AWG (actually 9.5 AWG since its 6 mm2) white wire to replace all the original ones that did not look that great in places. Might as well do it well when I'm messing with the electrical system.

I'm still hesitant about how to hook up the fusible link and also I have now done some reading about this mystical thing. One thing I'm sure about is that one is not supposed to use any odd wire to make a fusible link like I have done... There are dedicated wires that one is supposed to use to replace a broken/missing fusible link. Found some on eBay but the shipping to Sweden is twice the price of the wires themselves! Trying to source it here in Sweden is no use...sometimes I hate living is the outskirts of the world!

[Paxman]

OK, I'm getting cautiously optimistic here!

Today I installed all new white cables to a terminal block for common hot feed. I also found the remains of the original wires for the ammeter hook up which I tested with a multimeter for continuity and also what I'm pretty sure is the original fusible link! I connected it all to the system to the best of my abilities. With some hesitation I turned the main switch listening after the snap sound of a fuse or wire burning off and sniffing after the characteristic odor of really hot wire insulation but nothing indicated that there was anything wrong. I did hear the clock start ticking and I tested the headlights and other users, all seemed good. Holding my breath I turned the ignition key...the car started as is should and nothing bad appeared to happen! The ammeter did not move though so I hooked up the multimeter to check the voltage. The charging seems to work now!! So, why didn't the ammeter move...? I disconnected the original wires and hooked up the ones I used before and that made the ammeter react so obviously there is something wrong with the original wires. The needle was not rock solid all the time though, it flicked back and fourth quite bad sometimes so I think there is still something that I need to tweak. I'll do some more testing and maybe shoot some video. Also I need to take the car out on the road to see if the charging issue really is solved so I have some interior trim reinstalling to do.

To be continued...

Oh, forgot to tell you, I ordered a set of 16 AWG fusible link wires from eBay...they are on their way (I hope!) so one of them will be installed as soon as they get here.

[Paxman]

Nope, there is still something seriously wrong...

Today I shoot a lousy cellphone video showing the voltage and the ammeter. Note that the voltage at first is over 15 volts...
When the ammeter goes crazy I can see all the lights dim in sync with the ammeter needle. I can also hear the engine sound change when the ammeter goes ballistic...



I got the fusible links so I made a little holder for it and installed it in the engine bay (read somewhere that you should not have the fusible links inside the car). The original wires for the ammeter now have the wrong resistance so the needle deflection is minimal. With the long 16 AWG wires to the ammeter and the 16 AWG 9" (23 cm) fusible link I got almost too big deflection so I think I might need to do some tweaking there but that will have to wait till I get the charging under control.

[Paxman]

Went back to the original regulator and the violent fluctuations disappeared. Voltage was too low as before but I managed to adjust the regulator so I got it a bit higher. It's still not good but the needle deflection is now pretty perfect! The needle is a little bouncy but now it's more lika a few millimiters up and down from the average value, not the max-min deflections as in the video. I'll try to do a new video today to show you how it looks.

[CELICA1.6GT]

Hello all,


I recover this link because I'm in the same problem with the ammeter. You solved the problem?? ....

I would be very grateful for any pics or circuit diagram.

Thanks to andrewzuku and Paxman for the interesting link.

[Paxman]

What problem is that CELICA1.6GT?

[CELICA1.6GT]

Hi Paxman,
The problem is that lacks the connection from the battery/alternator to ammeter, the combination of wire to give power to ammeter, not exist. Some unprofessional electrician years ago eliminated these wires .

I today tested the ammeter with a bulb as did andrewzuku "Body Repair Manual" on the first page, and if it works.

Could you tell me, as you did the connections? .....some scheme/drawing or pic would help me, I'm a little "clumsy" with electricity.

Thanks avanced

[Paxman]

andrewzuku posted the schematic in the first post of this thread.

The reason someone eliminated the wires in your car could be that the ammeter is considered hazardous, some reports of setting cars on fire has been reported. If you are "clumsy" with electricity you might consider leaving it alone, for your and your cars sake. Just a friendly advice...

[CELICA1.6GT]

Thanks for the advice, wise advice, rightly....he he.
But I refuse to leave without working the ammeter. However if it is complicated for me, I'll go with the Celica to a qualified electrician.

First, I will try to locate the wires to ammeter ..... just to confirm that there are still. I take a picture to put here.