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Hey guys its been a while since ive been on here since the trans went out a couple years ago on my 02' rx300, well it was sitting and i just recently discovered rat crap all in it well turns out they pissed all over the entire engine, inside all over the car, it was bad, so i went to connect a battery to make sure i had power to everything and nothing, i connected the battery and it showed 12v to the starter and alternator wires but no light or anything come on, no fuses are poped and i looked at most of the wiring and it looks fine, i was in the process of disconnecting everything to get it ready for a new trans i never got around to finishing it so idk if i didn't connect a ground back properly or if the fate of the rats getting ahold if it did it, i fd it strange that not one electrical component worked, no door lights, no clock, no dash light, no chime, im just wondering if they could have chewed wires to everything and i i find that a little hard to believe because the wires looked okay, i just dont know what to do at this point, is so sad to see this happen all because my damn neighbors had rats and exterminated without telling me, so here comes the little bastards to my car. 😔😞
For starters, what does work? Can you start up the car?
Did you check main fuses under the hood? Does the voltage come to the fuse box at all?
Check if you have ground coming from the battery. Do not use a multimeter for that, take a 12V light bulb, connect one lead to the positive side of the battery, and use the second one to probe ground spots. That will give you a much clearer readout than a standard multimeter.
The next step will probably be to figure out where you are loosing the voltage. Try taking out an arbitrary relay (headlights relay for example) and see if it has a constant voltage coming to it, then turn on whatever the switch that controls that relay, and see if you will get any power on the coil side of the relay.
If you won't get any constant power, it is probably a bad link between the fuse box and the battery. There are two links coming from the battery - one goes directly to the starter, and the second one comes to the fuse box, you want to check if there is a continuity between the fuse box and the battery.
If you won't get any power on the coil side of the relay, it will mean that there is no connection between the switch and the relay, which is really bad, since it may indicate that you will probably have to replace the entire harness under the hood.
For starters, what does work? Can you start up the car?
Did you check main fuses under the hood? Does the voltage come to the fuse box at all?
Check if you have ground coming from the battery. Do not use a multimeter for that, take a 12V light bulb, connect one lead to the positive side of the battery, and use the second one to probe ground spots. That will give you a much clearer readout than a standard multimeter.
The next step will probably be to figure out where you are loosing the voltage. Try taking out an arbitrary relay (headlights relay for example) and see if it has a constant voltage coming to it, then turn on whatever the switch that controls that relay, and see if you will get any power on the coil side of the relay.
If you won't get any constant power, it is probably a bad link between the fuse box and the battery. There are two links coming from the battery - one goes directly to the starter, and the second one comes to the fuse box, you want to check if there is a continuity between the fuse box and the battery.
If you won't get any power on the coil side of the relay, it will mean that there is no connection between the switch and the relay, which is really bad, since it may indicate that you will probably have to replace the entire harness under the hood.
Hope this helps and best of luck!
Thank you so much! This will help a ton! I just quickly connected the battery to the terminals to check voltage at the fuses, and there was 12v also the alternator wires and starter wires had 12v, but when i open the door nothing no lights, no dash lights even when putting the key in to start, its like the car never had a battery.. if i have a ground that's not connected will 12v still flow through the car? Again thank you so much, this gives me quite a bit of info to troubleshoot! 😁
ignore the alternator (which is to help charge up) and the starter [one load to spin the engine] for now. The battery provides 12v and the electrons travel from the negative (-) terminal of the battery to the (+) positive of the battery through wires, fuses and load. Since the vehicle is made of metal, the engineers make use of this and eliminated one of the wires. So now the + of the battery is connected by wire to sequences of fuses, more wires, more fuses and switches, more wire, the load itself and then the other end of the load is connected to the chassis. There is a ground strap from (-) of the battery to the body.
The big fuses are in the engine compartment fuse box (next to the battery) and then they go to the cabin fuse box (next the driver's left knee).
Some circuits are unswitched ( you dont need the key .. always powered on). Test if the brake light comes on when you apply the brakes.
Check for 12v on all inside fuse terminals.
Beyond that you will need the circuit diagram to trace for the break in the circuit.
If the ECU does not get 12v, many of the functions will not work.
Some how mice love to nest in the glove compartment.
Like others have said power delivery and proper ground.
If you have no horn or hazzards you problem is between the battery(assuming your battery is good) and fuses so here is an easy circuit to test assuming proper ground. Hazzards and horn and brake lights do not need a key or go thru the body ecu.
PS- I'd start by following the negative battery cable and make sure it is attached to ground on car first cuz not likely rat chewed thru the main power wire it is very thick.
Exactly! Most of the interior chimes, lights, etc., goes through the ECU, so if you don't have power coming to it, you won't see any lighting in the cabin.
That is not something to worry about right now though, at this moment, you need to figure out if you have power at all.
Horn also doesn't go through an ECU either, so you can press the horn to see if it works. If not, measure where are you loosing voltage - either it is on the coil side of the relay, or on the constant side. You can find a coil side of the relay using an ohmmeter function - you need to find two contacts that have resistance between them, that will signify a coil.
Thanks so much all of you, Salim you hit the nail on the head, i had to disassemble the entire air box assembly where the cabin air filter is behind the glove box, and what do you know, right where the cabin filter was, piles of chewed up paper and crap! I had put some rat traps in there yesterday and what do you know, i caught 2 of them! 🤬 I have not had a chance to run the test since its been pouring rain for 4 days straight, unfortunately my car is not garage kept 😞 i will most definitely try today, everyone has been so helpful, i truly appreciate the wonderful members on this forum! 🙂 I will let you guys know what i find!
03-15-20, 05:22 PM
Rat Disaster.. Please help!
