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Reverse Polarized with Battery Charger

3K views 44 replies 5 participants last post by  lyrica 
#1 ·
2007 2.4 / 2WD - Didn't jump it backwards, put charger on backwards. Assuming damage would be similar, I did everything to fix it... new battery, tested /replaced every fuse everywhere (even did the dreaded 120amp fusable link) and I don't think it was even blown. It's Reading 14 amps from alternator. Everything works except -No PS or PW (& shift lock - all dash warning lights still on)
and it is not a fuse - all fuses related to PS & PW are good and I couldnt find that there are any relays that pertain to PS or PW in the diagrams? Please help! Am I missing something? Please don't tell me its the PSCM? The computer that you have to take out/remove the entire interior dashboard and intrument cluster to replace. This is a total nightmare that's been going on for 2 years. This is a beautiful RAV .. its like brand new, only 90,000 mi on it! OH... I guess a big question would be - 'How could I find out if it is the PSCM for sure? Because thats the real fear, what if I did replace the PSCM and then after all that .. it wasn't it! PS/PW still don't work.'
 
#3 ·
Thank you for your reply! I checked all fuses with a multi-meter, and found and replaced the usual suspects right off. Thats why everything else works fine, like A/C-radio-lights-...etc. There's actually 4 fuse panels. A regular OBD scanner doesnt tell you anything. I downloaded a real scanning software program on my PC, but ordered the wrong (incompatable wire) to hook it up. So no, no codes yet. I'm just asking for advice in the mean time? And probably might have to have it towed to the dealership eventually for a diagnosis. But no one likes or trusts the Toyota dealership here.
 
#7 ·
Hey espos4 : ) I did study all the diagrams. And there is or looks like from what I could tell, all kinds of 'diodes' leading to and from what would be PS, but they are buried so deep in the cars electrical system there is no way to look at' em and I dont know enough how to test them. I guess a 'diode' is somekind of extra fuse precaution built into the wires? I've also had two different views by guys on here with my first post a year and a half ago about them... one guy said that diodes dont burn out like a fuse and that its virtually impossible and goes against the whole nature of it... then another guy said...'No- they sure as hell do!'
I'm pretty sure the same problem is linked with the PS & PW together. If it was a reverse polar 'jumper cable' incident I would be fine now. But the reverse charging thing I think was way-way worse, because it was a 'slow mild feed of bad energy' that creeped through the fuses without blowing them, thats why the big 120amp fuseable link didnt blow (I replaced anyway) It would have been better if it were one quick big blast of bad energy so the fuses could do their job?
 
#5 ·
For the power windows….
Each window switch has a blue wire. Do you have power at any/all of those with the key on?

power for that blue wire comes from a power relay in the driver side end of dashboard fuse block. There are also 3 fuses for the windows there. 1 for both front windows and individual fuses for each rear window.
 
#10 ·
Your mention testing the fuses, but did you also check for 12v at the fuse terminal of the systems that you have issues with?
You don’t say if you tested fuses with a continuity tester or if you did it by checking for voltage on both sides of the fuse.
The attached picture shows that the fusible link protects the engine room fuse block, but there is a separate line from the battery to the starting/ charging system.

do you have 12v at the alt fuse 120A?
Do you have 12v at the EMPS 60amp terminal? That’s for power steering.
If you don’t have power at these fuses in the picture, you’ll need to solve that first.

I see this has been going on for a long time and it’s hard to get a good read on your electrical skills from a forum.
 
#11 ·
It was an old fashioned charger, with just a voltage meter, takes a couple hours to charge anything- No jump feature.
And I only had it on for a couple minutes before I realized..

I tested every fuse on the entire car (all 4 fuse panel/boxes) with I guess you'd call a continuity tester/multi meter, just that they were good (green light on both sides) I didn't necessarily look at the actual voltage reading off the fuses. I did check the Voltage coming out the 120A alt fuse link /terminal and it reads 14v which its supposed to ... not 12v, altough even 12v would mean its still ok. I've takin apart the fuse box. The 60A fusable link is good! I know because I surgically removed the top lid off it to stick the tester in, also replaced it anyway when I ended up takin the fuse box apart anyway to get to the 120A which never was actually blown to begin with, just I faced up to the nightmare take apart saga everyone was talking about, first off while I was sill just learning about everything. But I dont know how or where to touch on to test the actual voltage on the 60A terminal, like I do know how for the 120A voltage terminal. If you could read my posting again I thought I was explaining my extent of knowledge so far? I really am apprieciating this discussion : ) and thank you for the images.
 
#12 ·
Im down to ..'Do you think I ruined the PSCM (its the other Computer module [not to be confused with the ECM] that runs the power steering and also mentions the power windows) and how can I test that? Or is it even possible to ruin it... I thought thats what fuses are for to begin with?
 
#14 ·
If you remove the 60 amp fuse, you'll see 2 terminals down in the slot of the fusebox where it was mounted. Use your volt meter. Put the negative probe on the battery negative and use the positive probe on each of those terminals (one at a time). one should have 12v.
 
#15 ·
I am thinking about how you would have damaged anything by what you have done. You have a battery that has the capability of supplying 350 to 800 amps if shorted and you applied maybe 10 amps in the reverse current. To me it would seem like the battery would see that as a load and would not let the charge reverse flow current to the car. I need to do a little more thinking about that. Also seems like charger would protect itself and shut down or blow out.
 
#20 ·
Hi Automender! Right... like thats why the big 120A alt fuse and 60A PS fuse never did blow out... the only two fuses that blew were the 20A radio and one of the 10A ECU fuses.
The battery was completely dead and not even taking a charge... the needle on the meter on the old charger didnt even read anything when I connected it correctly, after I realized it was wrong. And I had got the new battery and swear I drove it around the yard and the steering worked and the shifter wasn't locked. I had the little fuses replaced already thats when I discovered it was in 'limp-mode' and then I fixed that! and was like awesome thank God! Then that's when I went to test drive it again... right off all dash lights were still on - I had to manually unlock the shifter- 'holy fk! the PS and PW don't work!'
 
#17 ·
I hear `ya... thats taking the fuse box apart again the huge pain : )
I would do that again, but I have access to the fuse on top ..couldnt I get the actual voltage read from there because I tested it and the fuse is good, I just didnt pay attention to the voltage. I would do it right now, but I borrowed the meter and dont have it.
I know youre think'in..'Dude wtf? get a meter!' lol
 
#19 ·
I hear `ya... thats taking the fuse box apart again the huge pain : )
I would do that again, but I have access to the fuse on top ..couldnt I get the actual voltage read from there because I tested it and the fuse is good, I just didnt pay attention to the voltage. I would do it right now, but I borrowed the meter and dont have it.
I know youre think'in..'Dude wtf? get a meter!' lol
No need to disassemble the fuse box. Just remove the fuse.
 
#18 · (Edited)
In theory you wouldn't blow any fuses that are rated higher than your battery charger amp output. Can you post a pic of the wiring diagram of at least the PS circuit.
Your alternator has a diode bridge which has to be rated higher than it's output so that is why they didn't get damaged. Using this logic you need to find the rating of the diodes in the PS circuit. I am not familiar with that circuit.

Do you have this warning light on?
Font Material property Circle Symbol Art
 
#23 ·
In theory you wouldn't blow any fuses that are rated higher than your battery charger amp output. Can you post a pic of the wiring diagram of at least the PS circuit.
Your alternator has a diode bridge which has to be rated higher than it's output so that is why they didn't get damaged. Using this logic you need to find the rating of the diodes in the PS circuit. I am not familiar with that circuit.

Do you have this warning light on?
View attachment 192055
Heres a link to a complete fuse/relay box diagrams
and yeah PS light is on... its not a steering wheel symbol it is just [P/S] light
 
#21 · (Edited)
So are all your warning lights on? If not is the steering light on? I am looking through the wiring diagram and noticed that the PS ECU is connected directly to the battery through the 60 amp fuse and it is switched on by the Main ECU. You have checked all the fuses but it maybe a control relay? Not sure. Did you try starting the car when it was connected to the battery charger the wrong way
Just guessing but it looks like you could have back feed the EPS ECU directly through that 60 amp fuse. Do you know were that ECU is located? If you blew a 20 amp fuse that would indicate the charger was 20 output and you would expect some signs of damage to the pins or connector to that module.
 
#25 ·
I dont see any relays that specifically say they are pertaining to the PS... And Man That is a scary Question...I really dont think I tried to start it with the charger on backwards...but it was like 2 years ago and there is a chance I might have??
The only 20A fuse I blew was the radio.
Yes the ECU is located behind the glove compartment and easy to get to. I have no idea how to test the pins or connectors though? And thats the Engine module and the engine runs perfectly. Now the EPSCModule is located behind the instument cluster and you have to take apart the entire interior dash board across the whole car to get to it... which if I knew for a fact that was the problem I would, but I would have to know before I did that. It says that computer module runs PW too. But yeah... maybe bad power got back fed through the 60A? but it didnt blow though
 
#27 ·
Yes on the 2007 the EPS warnging light is [P/S] just like that. And yeah, every single warning light is on when the car is running... but everything works fine, Except the EPS & PW.
Yeah Ive looked at and even booked marked that E-Bay page. But I cant find any other info about the EPS/ECU... except a you tube video of what it terrifyingly looks like to replace one.
 
#30 ·
Ok….. slow down.
your next step is to buy yourself a test lightand a DVOM. (Volt meter)
You can have both for less than $50 and are absolutely necessary if you want any chance of tracking down the culprit here.
Testing fuses is only part of the diagnosis. Checking for power and ground will tell you more.
 
#31 ·
Ok….. slow down.
your next step is to buy yourself a test lightand a DVOM. (Volt meter)
You can have both for less than $50 and are absolutely necessary if you want any chance of tracking down the culprit here.
Testing fuses is only part of the diagnosis. Checking for power and ground will tell you more.
Alright, I do need to invest in my own volt meter and get a test light. When I borrowed the volt meter and tested all the fuses, the only other test I knew how and where to do was the Amps coming out of the alt fuse terminal. Would you be able to walk me through a little on where to poke the test light for grounds and stuff? I think you're talkin' about like in the light switches and maybe on the EPS unit itself... things like that... and or maybe theres a way to access a wire to test leading to the EPS-ECU without having to take a lot of things apart.
 
#34 · (Edited)
You can get a cheap but useful multimeter from Harbor Freight for less than $10 but you also need a test probe light that will tell you if there is any current behind the multimeter reading. The electronic meters will indicate a voltage but they are so sensitive they don't load the circuit by design and sometimes fools you. The test light will draw an amp or two while the multimeter only draws needs micro amps to read a voltage.
 
#36 ·
That is definitely good to know... get the Mutimeter at Harber Frieght instead of an auto parts store, way cheaper!
Yeah and the test light is what I thought you guys were talkin' about ..that screw driver looking thing with alligator clips, that you use to ground it with. Man looks like I can get both of 'em for around $10 at Harbor Frieght and there does happen to be one in my little town- Yay
 
#35 · (Edited)
This is the link I used to look at the wiring on your car. It makes sense that an Toyota protected the ECUs simply by having installed a diode on the low current input power leads that will not let negative voltage flow into the ECU. But not sure that they would do it on the major power into the EPS ECU. Look at the wiring diagrams at the end of the link I attached.

.
 
#37 ·
Okay Im gonna study those official Toyota diagram links, I like how they are already separated- specific to each problem and read that reverse polarity protection article... thats crazy you found that! thanks.
And yeah you would think that if they paid special attention to protecting the ECU from negative flow with diodes, that, that would go for the EPS-ECU too? But you're saying not necessarily... maybe not?
 
#41 ·
Okay... I've been studying the PW wiring diagram you sent, and comparing it to the basic fuse/relay box - def / location diagram I sent you. You are right, on the real wiring diagram it does show PW relays! They are just not labled or shown on the other diagrams. I've been comparing the two to try to get a grasp on which is what and where. I am not afraid to buy new relays... if I can find an identical other relay to swap and test I will for the meantime. And yeah I hear ya' ultimately you still need the test meter and light - cause it might be the contacts too, not just the relay itself. The only reason I thought the EPS-ECU had something to do with the PW is that I read something while researching the EPS-ECU where it defined its functions and it said PW was one of them? who knows, anyway-
Wiring Issue! Here we go... the plot thickens`
I can't believe I haven't mentioned this before (A MAJOR COINCEDENCE) ... I've just been so overshadowed by the reverse polar incident.
At the exact same time of this whole thing, There was a horrible smell in the car, and I found a dead baby mouse in/on the cabin air filter. And the garage I keep the Rav in did always have a family of rats livin'in it. Its a nice garage I just ignored it. I've trapped them all out since. The rats might have chewed up some wires! It may have nothin' to do with the reverse polar? And remember I never even blew' the 120A fuse link... which is supposed to be the worse case scenario in a rev-polar incident. (unless theres still something to the slow feed of bad energy from a charger) anyway, And after I got the new battery and replaced the two little fuses that did blow... I did drive the car around the yard! and there was nothing wrong with the steering or windows... thats why they are stuck in down position right now.
So I'm pullin around - stop double check everything- a/c - radio -lights-etc. Discover something else just went wrong.. It's in limp mode? all of a sudden, I learn how to fix that... then pull it straight in the garage, leaving the windows down because I plan on coming right back and driving it around some more. A couple hrs later I go out, get in it, start it up... all warning lights still on? 'that's weird'.. go to put it in gear... it locked? 'thats weird' - stick a screwdriver in it and unlock it, then I back out of the garage--- The Steering is not Working? - oh sh*t!- either are the windows.

That mice chewing up wires has happened to me before (not same garage) I have an old van that I thought the Electronic fuel pump went bad on it, so I drop the tank to replace/fix it... and rats had chewed through all the fuel pump wires above the tank... I taped all the wires back together- the fuel pump was fine.
I'm gettin the test`o meters and light tonight or tomorrow! Thanks for hangin' in there with me!
And I'm gonna keep studing all the diagrams so Im up to speed and start routin` around maybe can find some obvious wire damage ... if I cant thats what testers are for - Yay!
 
#42 ·
I think you are on the right thought process. So you have been driving this car with the windows down and all this stuff wrong for two years? You just need to use the diagrams and look at the wire colors and probe the wires in question. It takes a long time but that's why having electrical issues fix costs so much money. Just keep going down a logical path and don't jump around once you have a plan.
I was going to suggest the swapping relays but I don't have that much experience with Rav4. But I have swapped relays in troubleshooting other cars. The PW must have some intelligence in the motors, do all your windows have the Auto feature or just the driverside?
 
#43 ·
I think you are on the right thought process. So you have been driving this car with the windows down and all this stuff wrong for two years? You just need to use the diagrams and look at the wire colors and probe the wires in question. It takes a long time but that's why having electrical issues fix costs so much money. Just keep going down a logical path and don't jump around once you have a plan.
I was going to suggest the swapping relays but I don't have that much experience with Rav4. But I have swapped relays in troubleshooting other cars. The PW must have some intelligence in the motors, do all your windows have the Auto feature or just the driverside?
No, I haven't been driving it... You can't, its way too hard- theres no steering. sure you could force it across the yard or drive it in a dire emergency, but it's too dangerous and would probably ruin it. Electronic power steering is different than older cars with belt driven pumps. You could still drive the car around, it would just feel like a car that didnt have the power steering feature.

Im pretty sure just the driverside has auto-feature.
Yeah Im gonna get the test meters and study the diagrams, remove whatever panels I can to get a look at/expose all the wiring that I can, identify and use the colors like you said. And when I get things narrowed down to specific questions and procedures I'm gonna message you and espos4 has got my back too. One thing is I don't have a total comprehension of how to find whether something is due to a bad ground or not, and maybe just the right places to check and what something might mean? Right and stick to the area you're on, till you understand it and what its telling you, before just jumpin over to something else.
 
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