Battery Fuse Box

Hi-
I'm having an issue with my van. First let me start off by explaining that a few months ago, I had my fuel pump replaced on my 1992 Previa. One issue I had with it was that the Check Engine light didn't come on at all. Tim said battery fuse box; my mechanic said fuel pump. I disregarded Tim's thoughts and went with the mechanic's: Bad move. I have been having intermittent issues ever since and everything went out last Thursday. Turns out that the box was bad my mechanic tells me after I should him Timsrv's posting and he tested it. When I went to pick up my van after the repair, my ABS light was on. I spoke to the mechanic and he asked if I could leave so he could look at it the next day. I agreed to it. The next day, I stopped by the shop four different times and they had one guy actually working on it when I arrived each time. They couldn't figure out why my ABS light is on. Does anyone here have any idea why the light is on? Like I said, it wasn't on before the repair so I doubt that there is actually ABS failure. However, I can't eliminate that option either. Any help would be suggested. Thanks in advance.

HERE is a link to your original thread over at www.toyotavanpeople.com. After reading about your mechanic's recommendations and how he's handled things so far, my 1st thought is maybe it's time for a new mechanic.......maybe it was a long time ago. That being said, Previas equipped with ABS have the main power for the ABS circuit wired through that fuse box. If you suddenly developed an ABS problem immediately after they worked on or replaced that box, then I would strongly suspect they created the problem. One thing that's important to note is Previas with ABS use a different box than Previas without ABS. Here are pictures of both:

Fuse box for non ABS Previas:
http://i8.photobucket.com/albums/a23...v/IMG_5384.jpg


Fuse box for ABS Previas:
http://i8.photobucket.com/albums/a23...v/IMG_0211.jpg


A fuse box for a non ABS Previa may or may not have internal conductors for the ABS fuse, so even if the fuse is there, it may not be hooked up to anything internally. Also keep in mind they could have used a fuse box from a non ABS Previa and switched the covers (making it appear they used an ABS fuse box).
Regardless of what they did, the 1st thing that you should do is pop the lid and make sure the fuse is there and it's good.

The fuse for the ABS is the large yellow one next to the small 20A ATC fuse on the right:
http://i8.photobucket.com/albums/a23...v/IMG_0212.jpg


If it's there and it's good, then pull it out and see if the box has metal conductors under it (one for each side of the fuse). If it doesn't then they used the wrong fuse box. If it does, then perhaps there is a problem inside the box. If everything to this point looks okay, then you'll need to remove the box and open it up. The bottom of the box is easily removed by disengaging a couple of simple snap connectors, then you can view the inside.

Here is what you will see:
http://i8.photobucket.com/albums/a23...v/IMG_0215.jpg


Make sure the black ABS power wire is there and is hooked up as shown, then disconnect the white connector and inspect the blade terminal and the female spade connector inside the white connector.

Here's what you should see:
http://i8.photobucket.com/albums/a23...v/IMG_0218.jpg


While you are in there, also check for burn marks and corrosion. Everything inside there should be clean and shiny.
Please check these items and report back. Tim

I told my mechanic what you said and he had no idea that it was a different fuse box. Hate to say it, but after this is corrected, I will be going to another mechanic. I should go back to doing this stuff myself but I usually don't have the time anymore. As usual, you pull me through these situations. I really appreciate you taking the time to helping me. Glad the site is finally up. I've been waiting for your site since you first mentioned it after the demise of Clubprevia. I have a feeling this site is here to stay and I will be a member for years to come. Thanks Tim.

I was wondering if they ever resolved this problem. Any updates???

Yes, the problem was solved with the new fuse box. You were right every step of the way on this one. The mechanic decided that he wasn't even going to charge me anything to replace the box... not even for the part. He told me that had I not received the info from you, I probably would've ended spending a lot more before he would've discovered the fuse box was the problem. I've since talked to two other Toyota only shops that had no idea either. Thanks again Tim. You always seem to know what to look for when other mechanics don't.

That's awesome! Glad I was able to help save you some green :dance1:. Tim

Hey there Tim, my 91 previa starts and runs fine but my check engine light dose not turn on in the run position with the engine off. Could I be having the same deal with the fuse box? I tried jumping the e1 and te1 to see if it flashes but its stays off. Could it just be the light? Or the fuse box.

If it were the fuse box the van wouldn't run. I'm guessing the bulb for the CEL has burned out or has been removed. The next step is to pull the cluster and check the bulb. Here's a link to a thread that will help you do this: http://www.toyotavantech.com/forum/s...auge-Dash-Bulb

I also have the oil light that's not lighting up. Is that to a bulb issue? I read on justanswer a guy had both lights out but his van was not running unlike mine. Is there a way to check the voltage to those light sockets ?

Yeah, but you need to pull the cluster before you can do it. Pull the cluster and check the bulbs 1st. Tim

Ok Tim, I replaced the bulbs, and its still not working. What's my next move?

Unfortunately I don't currently have access to my service manuals so I cannot give you specific information. I can however give general info. The check engine light is triggered by the ECU. The next thing to do is access the ECU and see if it's sending the correct output to the CEL. If it isn't then the ECU is bad. If it is then the wire harness may have a problem (somewhere between the ECU & the CEL). I have a pretty good idea on the oil light system but can't say for sure where to check unless I could view a schematic. Typically there should always be power to the bulb & the ground comes from the oil pressure sender. The contacts inside the sender are always closed, at least until oil pressure is present. At that point the pressure "floats" the contacts & prevents the light from coming on. Sorry about not being specific, but without the books or the schematics any more info would be speculation.

The best advice would be to get an FSM (Factory Service Manual) and use it to identify which wires do what. Then you can test based on that. Tim

It's ok Tim. You got more respect from me then I give to my local Toyota dealer. If not for you my headgasket would have never got done. So much props to you.

Ok Tim how would I check for a signal from the ecm. At the ecm itself or the harness that plugs in at the instruments? I tired finding something in the service manual but I can't find a thing and I am horrible with wiring schematics.lol my weak point.

As far as the oil light problem. Can I ground out the wire that connects to the oil pressure switch to see if it lights up?


Final question. Is there anyway these two light are connected in some way to cause my problems?

Ok Tim this is what I got so far. After work I pulled the instrument cluster again and using a test light I check for a signal. There was none. Also check at the ecu and there was nothing there either. Any ideas?

I'm thinking the problem with the 2 lights is connected, but without a manual/schematic I can't say for sure. Yes, if you ground out the oil sender the light should come on...........but only if the 12v+ is already on the other side of the bulb AND the harness between the sender and the bulb is intact.

When I check at the ECU I typically leave it hooked up and use a Fluke wire piercing tool. It pokes a little pinhole through the insulation and touches the conductor inside........sort of like a test light but much more precision (doesn't leave obvious puncture marks). Tim

PS: I'm very hesitant to give more info/insight without 1st being able to verify with my FSM (I don't want to give bad information). I've likely said too much already & not 100% sure on some of it. Tim

I checked the oil sending unit wire and the is no volts and I checked for voltage at the ecu check engine light wire and there no volts.

Tim, is it possible that the van runs but the ecu can be bad? i took my previa to toyota by my house and they are saying my ecu is bad. those buttheads are trying to soak me for 1500$.

Yes, as a matter of fact, 2nd to bulb issues the ECU is the next most likely place. It's very possible the circuit in the ECU that triggers the light(s) is bad. All it takes is an inexperienced tech with a test light and/or a test battery to fry a trace inside the ECU. Other things like corrosion & moisture can mess it up too.

You did say though that you checked that circuit on the ECU and it had the correct output..................right? If it really is bad, before I'd pay a new price I'd pull one from a wrecking yard for $50 or whatever. I see them on eBay all the time for about that price too. Swapping ECU's on a Previa is easy as it's right under the driver's seat. Just get the part number off of yours then do an eBay search using that number (be sure to click the "include description" box).

YEAH I TRACED IT ALL THE WAY BACK TO THE ECU. AND IT WAS ALL GOOD. THE DEALER SAID THE GROUND CURCIT IN THE ECU MAYBE THE REASON THAT ITS NOT LIGHING UP WITH THE KEY ON.

IM DO WHAT YOU SAID AND LOOK ON EBAY.

Did you ever get to the bottom of this?

as a matter of fact i did. and guess what tim? you were right again.lol bad ecu. i found one at pick and pull that matched my van and everything thing is gold. by the way on another thread i told you i was throwing out my"serviced by Folsom toyota plate frames and had three new plate frames made. at the top it reads " toyotavantech.com" and the bottom reads " In timsrv I trust. All hail tim, master of the toyota previa....lol ok i went a little over board there but if not for you tim my pour van Samantha would still be collecting rust. so ty very much. by the way the third plate frame is for you. just tell me where to mail it.

Quote:

---

Originally Posted by Previa dude

......... had three new plate frames made. at the top it reads " toyotavantech.com" and the bottom reads " In timsrv I trust. All hail tim, master of the toyota previa.....

---

Lol, How'd you fit all that on a license plate frame? :LOL2:

Glad to hear you got it fixed. Toyota ECU problems are rare but can/do occur. I finally experienced my first ECU failure a couple of weeks ago. My 86 van had been parked for almost 13 years and when I finally pulled it out of the black berries the ECU was shot (along with the fuel pump & several other things). Fortunately I had a spare & all is well. Now I'm using it for a daily driver. Tim