Cross wired jumper cables.....and messed my truck up.

Good morning, My name is Rich and this is my first time posting on this forum, so if I break a forum rule then please forgive me. I tried to search the threads, but nothing that met my needs came up. so here I am asking for help. Anyway, this weekend I went to jump start my Tundra (2003 V6, TWD) and accidentally connected the jumper cables backwards and, (so it seems) have really screwed up my truck (I've jump started at least a hundred cars in my life and have never done such an idiotic thing before). Anyway, because the battery was completely dead I didn't get the typical arcing you get when making a wrong connection, so I didn't notice what I had done and then proceeded to crank the engine. It turned over but obviously didn't start. I then checked and realized my mistake. After connecting the the cables correctly the engine started but the dash was now completely dead. While trouble shooting, I discovered that the 100A main fuse was blown along with about three other fuses. Stupidly, I did not make a note of which fuses were blown, anyway I replaced all the blown fuses and replaced the battery. The engine will now start and idle just fine, however when I try to give it gas it will not accelerate until I have depressed the pedal about an inch or so, then it revs to a higher than normal RPM. Also the Check engine light is on, and when I put it in drive the shifter indication light in the dash will not light up for drive, but it does light up for the other gear positions. It will go into the drive position and it will drive, however I didn't try to go over 20mph as it seemed to want to shudder as soon as I start approaching that speed. Lastly, I tried to use my new OBD scanner to check the codes, the scanner powers up but will not link to the ECU and fails with a communication error (this is the first time that I have tried to use the scanner, so I don't know if it is the scanner or a bad connection or what ever). I'm afraid that I have toasted the ECU or some other critical sensor. Can anyone offer suggestions on my next steps? Please try not to suggest that I take it to the repair shop, as that will be my fall back position if I cant figure this out on my own. Any help will be greatly appreciated.

Thanks

 

Welcome to the forum. Sorry to hear about the truck troubles, we all do some dumb stuff some times. The “D” light drive position indicator doesn’t work in a lot of these old Tundras, so I would t worry much about that. You can pull the instrument panel and replace the bulb, good time for an LED conversion. Your OBD issue and your motor issue could be simple problems like a fuse, or sensor that got zapped, or a bigger issue like ECU problems and alternator issues. I would start by checking every fuse and focus on getting the OBD port back up and running. You may simply need more drive cycles for the OBD to “reset” and register the codes. The check engine light code will point you to whatever the next task will be. Maybe a MAF or TPS. Or hopefully not bigger computer issues. Good luck with this.

 

First I would say don't feel to bad, mistakes happen especially when people get in a hurry. I have seen well trained techs make this same mistake.

I don't know the first generation Tundra (2000-2006) as well but my advice would be to diligently check every fuse in both fuse boxes again. The engine fuse box and the interior fuse box under the dash. Some components of your truck are still not being powered properly.

The fact that is still runs and drives tells me most likely your main engine ecu is fine, however some other Ecus are not getting power and operating correctly. Are you sure the key is one when trying to connect the scanner? I think the truck has fuse and power going to the OBD port. If that fuse is bad maybe it is keeping the scanner from properly communicating.

 

First, Welcome from LA (Lower Alabama)! The first two thing I would do are 1. Check EVERY fuse and replace those that are blown. Some that you replaced before could have blown again. Pay attention to those for further troubleshooting. 2. Disconnect the battery for at least 15 minutes to allow for a full reset of the ECU.

Actually, swap the order of those two things. Good luck in your troubleshooting!

 

I would pull every single fuse (assuming you haven't) and check continuity of the fuse (not just a visual inspection). If it runs I would think it'd have power to the OBD port. I'd bet there's just another fuse blown.

 

I read it that he has power to the OBD port, but it’s giving him an error message instead of a code.

 

The OBD only uses 2 ground and 3 communication lines (its not CAN, some older protocol) to the Engine ECU. Either the 7.5A OBD Fuse is bad or a different fuse that powers part of the Engine Control Module. I missed the part where he said the scanner had power. Assuming its not internally powered by a battery, the OBD fuse is most likely good and he has a power issue with the ECM still.

But yes it seems the ECM is not responding the the initialization messages from the scanner so we get no trouble codes. Let see if he finds anymore bad fuses.

 

Sorry, to clarify I would think the OBD2 would have communication if the ECU is functioning. In my extremely limited experience with the OBD2 it has only a few wires that actually do anything and usually they run directly from the ECU, so if the ECU is working and those wires are intact, I'd guess there's a fuse on the communication lines that's not allowing the signal through.

 

I would like to say thanks for all the responses I've received so far. To be sure, I will pull and test every fuse in both fuse boxes again (except for the 100A main which was a nightmare all by itself to replace, I cant believe Toyota has such a bad fuse box design). I agree that one or more could have blown again (which would be troubling) But I can see that it could happen. Also, just for clarity sake, the OBD port does have power, when I plug the scanner in (it does not have an internal battery) it lights up and then tells me to turn on the ignition, when I do that it goes through (what I will call a start up sequence) by checking a series of codes, but then it gives the communication error message. If I cant get the scanner to connect, I'll try to borrow one from the Auto Parts store through their tool lending program just to make sure it isn't a problem with the scanner. In my first post I mentioned that the drive indicator light does not illuminate when I put the shifter into drive. I agree that the electrical shock the system took may have blown the bulb, but I can attest that it was lighting up prior to my inept blunder. I won't be able to check anything until I get home tonight, but I will post the results.

Thanks again for all the suggestions.

 

Make sure you check the interior fuse box as well. Under the dash drivers side. Some users forget or are not aware there is a secondary fuse box inside the cab. This one will have fuses for interior components, gauges, radio ect. Since you have already gone through the engine compartment fuse box, I would start with the interior one. A fuse or two replaced there could fix all your problems.

You could try your scanner on a separate vehicle to make sure it is working.

 

Also, I have had instances where the fuse under the dash had continuity (toned on my fluke) it still ended up being bad. Since that happened I go through the hassle of pulling fuses to make certain they are good.

Good luck!

 

Do a search on "fusible link issues" in the search field in the upper right of the screen. Sounds suspiciously like the issues listed there.

 

Solved....(mostly).

First let me say thank you to everyone that responded yesterday and offered up suggestions. So...as I mentioned in my original post that I had checked and replaced all of the bad fuses, which I did do. After yesterdays discussions, I went back and rechecked every fuse in both fuse boxes and was surprised to find that a 15A fuse labeled ETCS that had blown and was replaced previously had blown "again". I have no clue why it blew a second time, but I replaced it again, reconnected the battery, started the engine and to my amazement the check engine light cleared and everything was back to normal! It runs and drives just fine. I'm super stoked that this solved the issue! Hopefully it will not blow again. On the other-hand, the OBD scanner will still not communicate with the ECU. I did check the scanner on my Mazda and my wife's Lexus and it connected perfectly on both. So I'm guessing I have a wiring problem, or the scanner is not compatible with a vehicle this old. Either way, it does not matter since the truck is now running fine, and I'm just not worried about it. I still have a blown bulb for the drive indicator that will probably never get replaced..LOL, anyway...all is well for this problem...next issue is a bad power steering pump or the steering rack has gone bad or both, but that is for another thread...The joys of owning an old truck. Thanks everyone.

 

That's awesome! A simple fuse that costs next to nothing can cause so much chaos!

 

Give the truck a few more drive cycles and check the OBD plug again. I think it will self sort.