Hello! I picked up a 95 4runner 4WD 3VZE 5 speed through an auction that I've been tinkering with and can't seem to get it to fire. Replaced the battery and got it cranking but I cannot get any spark or fuel. I unfortunately rushed into it and threw some cash at it, namely a new igniter and ignition switch ($$$) as that's what some short googling suggested. Both of these didn't work and now I'm stumped. Here's what I've done.

* I've directly fed power to the fuel pump and it works, cracked the banjo fitting on the fuel rail and I get fuel.
* New Battery
* New Igniter
* New Ignition Switch
* All fuses are good. I do not know how to test relays but there's lots of clicking happening when turning the key to the 'On' position

It seems that other than the starter cranking and dash/interior/exterior lights I have no power going anywhere. With the key in the 'On' position the driver kick panel 7.5A IGN fuse gets .06 volts, the +B in the diagnostic box gets .06 volts and I get zero voltage at the AFM, Igniter, Coil or Dizzy. No fuel while cranking, no spark, nada. No check engine light either. Any leads or help would be greatly appreciated, thank you!

 

"loads of multimeter testing" tells us nothing be specific.

I'd probably start with pulling fuses untill I got battery voltage on the vbus(batt, B+), i f pulling fuses doesn't get you there is pull the efi relay and so on...

You can do resistance checks to ground with the battery disconnected, the closer you are to a ground short the less resistance you will wee when probing what should be a battery voltage wire.

 

Sorry about that. 'Loads of multimeter testing' is probably a redundant point I added, I'll edit it out. Primarily I've just tested what I listed, (IGN fuse, B+, AFM, Igniter, coil, distributor.) To my inexperienced self that was 'loads' as that's the most I've probably ever used my multimeter! Haha.

What do you mean by pulling fuses until you get battery voltage and what is a vbus? Remove 1 fuse at a time while constantly checking the B+ terminal for battery voltage? I apologize in advance for my inexperience.

I think I know what you mean by searching for a ground short but I always get confused once a wire goes into the harness or loom and I lose it, especially seeing as the IGN fuse is under the dash and pretty cramped... I suppose knowing where each wires goes to and from is a requirement here or am I missing something obvious? I realize this may be a dumb question but as I said I am quite inexperienced. Checking voltage? No problem! Tracing wires and using Ohms? Ooh boy do I have some learning to do! Thanks very much! I'll do some more googling and watch some vids to learn a bit more about finding shorts tonight and hopefully have some daylight after work tomorrow to test some more.

 

Vbus isn't really a term, sort of, so I'll apologize. In this case vbus is your "batt" and "B+" at the ecu which I kind of aluded to, which you are seeing the zero or point six volts at the ecu and other test points.

So start at the battery terminals, probe ground on battery negative probe positive on the battery positive. Do you have more than twelve volts? Ok move to the junction box (AM1 on your diagram), do you have battery voltage (~12v)? Then work your way across the fuses in the junction (distribution) block. If you see the low voltage 0.6v pull the fuse and check there is 12v on the supply side. If you don't see the same voltage as the first test directly to the battery you have a bad wire or a short, and if you do you know the short is cause somewhere down stream of that fuse. Now once you've found the bad circuit you switch to a resistance to ground test, so you leave one probe on the battery negative cable and put the meter into ohms test and write down the reading from the drain side of the fuse you pulled. With this number in mind you need to trace out on the wiring diagrams what is down stream of the fuse and move to the next connector. So say (making up numbers) your resistance to ground at the fuse is 1 you move to the next connector and see a 0.5. Disconnect the connector and measure each side. If you get 0.5 on what should be the supply side and say 20 on the drain side you know there is a short on the supply side (the closer you are to a short to ground the lower the resistance). But if you still get a 0.5 you know it's down stream (or that's the normal resistance of that circuits load.)

So you work your way through the harness testing each side of a connection untill you find a section of wire or component that has caused the short.


You will know you've found a bad component or section of wire that has a short by a huge change once you remove the component.

Some typical suspects are the efi relay, the oxygen sensor (which usually blows a fuse unless someone has bypassed the fuse or stuck a way to high of amp fuse in it..)

There are plenty of videos and howtos by people that have put way more time into explaining this sort of stuff (finding shorts in automitive wiring) than I have or will.

Lots of ways to go about it. Start maybe with cutting a circuit in half by say unplugging the ECU and testing "batt" and "B+" and if you get the same result as measuring across the battery terminals you know everye upstream of the ECU is fine.

 

EDIT: I totally missed the last thing you posted. I can go check that real quick, is 'batt' a specific point or do you just mean the battery itself? Sorry, that's totally my bad. Also, in the diag box thing I have +B not B+ am I doing something wrong or looking in the wrong location?

Had some time to test today. I get full battery voltage to AM1, Head relay, Starter relay and in the diagnostic box thing I get battery voltage to W, Ts, Tc and that's it. No power to AM2. I don't have have any amp draw so wouldn't that mean I don't have a short somewhere? Multimeter Positive lead on negative battery post, Multimeter negative lead on negative battery cable I have zero amp draw with doors closed, .55 with the door open running interior lights. I ran a wire from fp in the diagnostic box directly to the positive battery post and my fuel pump kicked on like a champ.

I did some searching and found a post where a guy says to check the ECU E1 terminal for continuity using the closest to the ECU body ground available. I'm not entirely sure I did it correctly, but touching the post on the ECU itself I did not get continuity, touching the pin inside the connector coming from the harness I did get continuity. I'm starting to think my ECU may be bad? I suppose I need to know the path power takes in this vehicle to test whether I get power to the ECU but not after, or some such? Should the EFI relay have power only when cranking, or when the key is turned on? I have no power with the key on to the EFI relay or the COR relay. I don't mind buying a new ECU, or any part however I want to make sure I find my actual problem first as I've already spent roughly $230 on parts that weren't my problem rushing into things. Dumb, newbie mistake I know. Should be able to return them, though. It'll be dark here shortly so I won't have the chance to test anything else until the morning.

 

Have you had any luck? I had the same problem, engine cranks with no spark. No check engine light, and I also had fuel pressure. I ended up having a short circuit inside my VAFM. One of the tiny solder joints broke off in the sensor and managed to short out the entire ECU. What I did might be a long shot for you, but it doesn't hurt to try. If you unplug the wiring harness at the VAFM, see if you get a CEL. If so your engine should start and run for about a second before shutting off. If that's the case, then you gotta open up the sensor and find that short circuit, or replace the sensor. On mine, I had a 1 mm wide piece of tin stuck between 2 wires, that I had plucked out with tweezers. I have no idea how you would go about using a multi-meter in this context to find a short circuit.
I am aware my solution may not be helpful; if I send you down a wild goose chase, I do apologize.

 

AM2 supplies power to the efi relay, among other things .

Disconnect AM2 and check for voltage on the battery side of it. If you don't have battery voltage on one side of this your initial fault is somewhere between the FL wire attached to the distribution plate and AM2 (since you have power to AM1) and it shouldn't be hard to find since its with in single digit inches of AM1 which you say has power.

It's only a 30amp Fuse so pretty easy to have blew out. By say shorting out the positive wire at the ignition coil or the fuel injectors both of which are only fused by AM2. You also have the EFI and IGN fuses on that leg of the circuit, did you have to replace either of those? If you or someone else bypassed or replaced those with higher rated fuses the fault could be on those legs of the circuit also or they should have blown also or first.

 

Quick reply before I crash out. Work has been a mess, had 2 rigs go down so just got home after 14 hours. I haven't had a chance to work on the 4runner. Should have a few hours free tomorrow. Thanks so much for all the help! I will update as soon as I can.

 

Great news! One of the wires that screws into the main 80A fuse wasn't making contact, I now have fuel when cranking and 12 volts to the coil. I didn't get spark however, but I need to do a run through and make sure I didn't leave anything unplugged. I was in a rush as it was raining and slowly getting worse, now it's too bad to be out in the driveway with everything exposed so I will have to pick up tomorrow for a full report of where I'm at. @ Co_94_PU you're the man! Will update tomorrow asap!

 

Sorry for such a late response. No apologies necessary! It's something I'll keep in mind and check out tomorrow if I'm still not getting spark with the progress I've made so far. Thanks for the input!!

 

I'll get it out of the way. She runs! Yes, the 7.5A IGN fuse and 15A EFI fuse were indeed blown when I got it. I think I was chasing my tail the entire time and it was the disconnected wire to the big 80A fuse. I only ran it for 15-20 seconds as there is nearly no coolant in it, but no CEL's. Next up is new fluids/filters all around the entire truck, track down a major exhaust leak and so forth. Co_94_PU, I can't thank you enough for all the help! Most of the problems were probably my own fault, but you gotta start learning somewhere.

 

Hey that's really cool that it runs! I'm glad it was as easy as a blown fuse, and not some insane rabbit hole. Electrical problems are the worst.

Have fun with the rest of the project! I think it's safe to say, everything i learned about my 4runner I've learned from this forum. Do you have a copy of the service manual?

 

Electrical problems are definitely the worst, especially if you aren't well versed with wiring. Thankfully Almost all of the wiring looks to be in exceptional condition for an older vehicle.

I did download a folder with the FSM for 1990-1995 4Runners, but I can only open it through a browser even though it's accessed locally on my SSD. A full PDF would be a thousand times more convenient since I can't seem to access it on my phone and have to run inside to my PC to look things up. I'm actually buzzing through the manual right now putting together a full list of all the fluids I'll be needing to buy. Front/rear diffs, transfer case, trans, engine, coolant, etc. (filters too) It's a wealth of information, super useful.

 

I use this on my phone.
https://ether3al.com/runner90-95fsm/
It's even broken down nicely into each section. The organization is a little confusing but it works great on my phone.
There! I accomplished something helpful in this thread!

 

Copy that (HTML based?) FSM to your phone, most PC's have the ability to print to a PDF and all of them can print to PS (PostScript) files..

Electronics are only scarey because someone told you they were, it's no different than the physics you can readily see in other mechanical subsystems. I mean you need things like calipers and micrometers to measure bearings and such, a multimeter is just another tool!

 

How true. It reminds me of when I was tutoring Statistics at the Community College. That was the "final" course for many majors like nursing. So many of my tutees (yes, that's a word) would say "I'm terrible at math. I've always been bad at math, including high school. I hate math!" Often they were of one gender, and had just been "told" that math wasn't for "them."

So suck it up! Our Toyotas are barely electronics; the problems we all face are just electrical. Play around with that $6 multimeter, and soon you'll be yearning to take on a Tesla!

 

You guys rock so hard!!

Co_94_PU, that's a great way to look at it for sure man. I've already learned so much more about how to use my multimeter just in these last couple days. I'll get there. The manual I have is like 460 sub folders full of individual pdf's that are all called up locally via an html file through chrome. For my 2009 GSXR 1000 I have a service manual pdf I can bring up on my phone and type in whatever I want and it'll bring up whatever I search instantly, if I could somehow condense all of these pdf's into 1 meta pdf that is fully searchable that would be fantastic. I don't know how to do that however. Doing some googling now, maybe that'll be a project for a different day.