Ra23 electrical problem.

**rob1** · 17-06-2006, 04:31 PM

Mos you champ. It doesn't! But the full voltage one is only full when the engine is running. I assume the one that is on when ign is on but the engine isn't running, is ignition power. The other (which is giving me a full reading) is the alternator output, seeing as it has to be in operation (eng running) for the output to be active.

So my ignition input is faulty.
This sound right?

**rob1** · 17-06-2006, 04:34 PM

Originally Posted by Mos

If you're sure that it's supposed to be 7V, depending on where you measured 5.6 it could be a couple of things. You really need to find out what it should be for sure (eg check a car that works) otherwise you may be chasing the wrong problems.

If you measured 5.6V between the dash reg and chassis, then something is causing the 7V to droop - that could be a sensor drawing more current than it should (try unplugging things like water temp, fuel sender, etc) or something shorting out a wire that draws current from that supply.

If you measured 5.6V between the dash reg positive and the dash reg negative, then it's more likely to be a dash negative grounding issue but it could still be the same reasons as above. (Grounds in toyotas are normally white with black stripe, or brown in colour).

Mos.

I know what your saying here Mos, but my logic says now that if I can rid the charge light problem, it may in turn fix the other problems. The ignition input to the charge light sees to flow through other gauges on the back of the circuit board, so you can see what I mean. Whether it will fix the tacho....not sure, as with the heather fan. I temped a 12 volt to the ignition input and the light went out, I'll see if it fixes the other gauges as well.

**Mos** · 17-06-2006, 04:41 PM

Originally Posted by rob1

Mos you champ. It doesn't! But the full voltage one is only full when the engine is running. I assume the one that is on when ign is on but the engine isn't running, is ignition power. The other (which is giving me a full reading) is the alternator output, seeing as it has to be in operation (eng running) for the output to be active.

So my ignition input is faulty.
This sound right?

Yep, spot on

**Mos** · 17-06-2006, 04:43 PM

Originally Posted by rob1

I know what your saying here Mos, but my logic says now that if I can rid the charge light problem, it may in turn fix the other problems. The ignition input to the charge light sees to flow through other gauges on the back of the circuit board, so you can see what I mean. Whether it will fix the tacho....not sure, as with the heather fan. I temped a 12 volt to the ignition input and the light went out, I'll see if it fixes the other gauges as well.

Yep - isolate the problem you know about first. I would trace that supply back until the cause of the voltage drop is found rather than just supplying power externally.

Mos.

**rob1** · 17-06-2006, 05:01 PM

Ok. When running a temp ign source to the proper ign input to the said black plug, it blows my temp fuse. However, I cut the wire and tried again, only to the circuit board, and no dramas, the gauges and charge light are fine. Tacho and heater fan still don't work obviously. So I have isolated the problem to be back down the line in the ign input wire. Probably a short. If I can find where the short is, I should solve both the tach and heater fan prob as well.
I wouldn't be surprised if the brake light and reverse light problem I have are related as well.

Thanks very much Mos. Your help is greatly appreciated.

**BrianRA23** · 17-06-2006, 05:21 PM

EDIT: Took too long to write this, sounds like it is sorted:

I assume by now we are happy the alternator is putting out the right voltage to the charge light. If the fuse providing power to the other side of the charge light blows then the light will come on, so if the voltage on the same side is low then the bulb will dimly glow.

There is a voltage drop on the "everything but the engine circuit" somewhere from the key back and I think the brake light issue is separate. It doesn't sound like an earth issue. The voltage drop is either from a bad contact or something draining more power than required, but for this type of power drain you would blow a fuse (if correct rating is being used) and everything else should continue to work so I would steer toward a bad connection in the wiring for power.

Check the voltage coming from the key for the non-engine circuit since maybe you have burnt contacts. This should go to the fuse box, which will supply multiple items with power (dash, heater, radio, demister dome, brake lights etc) and again may be a bad connection of the wire onto this point.

Use the multimeter to get a voltage all the circuits in the fuse box, maybe with the fuses removed. Note any differences and then after the fuses are inserted.

**rob1** · 17-06-2006, 05:39 PM

Main thing is, I didn't know how a charge light operated. I do now. And it's made the whole thing make sense. The heater fan and tacho also only have power when the key is on ign as well. So I would assume they are related. As for the rear light problem(s), I'd say you are right with them not being related. But I think I have an idea why this seperate problem is occuring.

Next step is to check the fuse box, or the loom to the dash guages.

It's dark here in Tassie now, and cold. The beer is flowing so that's tomorrows project.
Cheers, Rob