RT142->1GGTE wiring help

**Pube** · 09-12-2006, 05:55 PM

I im in the final stages of transplanting the 1ggte from the old corona to the new one. The wiring was a bit different but I have managed to get the engine wired up and its running with no fault codes. However I cannot seem to get the charge light to turn off! Have put a multimeter across the battery and its charging at a high 17V but with the lights on it drops back down to about 14.5V. Is that too high and would this cause the light to stay on?? I have also trimmed down some of the wiring in the engine bay to tidy it up. The wire of concern was the thicker white one that connects directly to the alternator runs into the fuse box and runs full circle around the engine bay. When I trimmed it around the fuse box it became a bit confusing as the wire splits into 2 then joins back into itself here and there. Has anyone got a basic wiring diagram of the main power wire so I can wire it all again? Also would this be a cause of my high voltage and battery light staying on if I have miss matched this wiring?

**The Witzl** · 09-12-2006, 06:31 PM

i have an RT142 body manual, including wiring diagrams. The real Toyota one, not a Haynes etc.

see my FAQ on internally regulated alternators, might answer a few questions - but to me it sounds like you've munted the "S" wire (voltage sense) when you trimmed it off the fuse box.

**wilbo666** · 09-12-2006, 09:33 PM

Yeah I'm with Witzl,

Sounds like the 'S' sense wire might not be connected.

The S wire is meant to run from the battery +ve terminal to the pin on the Alternator.

The reason that the large gauge wire that charges the battery isn't used for sensing the battery voltage is that the large charge current from the alternator imposes a voltage drop across the wire (V=IR...say I=30A then the small resistance of the wire from the alt to the battery causes a voltage drop that is significant). To avoid this, and measure the accurate voltage at the battery the setup is to run a separate wire from the battery to the Alt (the S wire), that doesn't draw any current and hence doesn't have any voltage drop.

Cheers
Wilbo

**Pube** · 09-12-2006, 10:29 PM

ill have to mess around with the s wire in the morning. Im guessing my wiring for the ecu has nothing to do with this charge light? It will be wiring in the engine bay? If the S wire is not connected, does that mean the charge light stays on?

So what I have figured it that my biggest prob here is finding out which wire on my car harness is the wire for the charge light? I have the ignition wire and now the sense wire to the battery +. Gees I hate wiring!

**IN 05 NT** · 10-12-2006, 07:33 PM

if its charging at 17v.its way to high...and will cook your battery...monst likely a faulty reg..

should be round the 13.5 - 14.5 with NO ACCESSORIES on...

if the lights not wired to the alt....take the bulb out...lol

**Pube** · 10-12-2006, 07:44 PM

The alt was working fine in the old car and the charge light was off. I checked the voltage with a mulitmeter at the alternator and it was about 14.5V but at the battery it was 17V. I havent had time to work on it today but ill toy with it tomorrow.

**Pube** · 11-12-2006, 12:00 PM

I have just double checked with a mulitmeter and at the alternator its pumping 17.5V. I know this is too high and hence cause my light to stay on? It has just getting my confused as it was working fine in the other car! I guess I need to get it rebuilt to hopefully solve that problem. I have checked the 'S' wire (black) and the alt is geting constant power from the battery, getting ignition (black/yellow wire) but im guessing the 3rd wire is the light wire (yellow)? They all run into the fuse box into the same plug.

Is there a test to check the battery warning light works? From what I have read and can remember, the battery warning light turns off when the alternator regulator earths the 'L' wire? The ALT fuse in the fuse box isnt getting power either. So the reg is stuffed? Help!!