Gee a lot of great ideas but no brass ring…

Your right front tire – sounds like it’s out of round to me – jack the truck up just so the tire clears the ground, get the biggest hunk of white chock (spelling?) that you can find and a 4x4 hunk of wood. Hold the chock on the end of the 4x4 and while a buddy spins the tire move the 4x4 with the chock up to the tire VERY slowly.
If it’s out of round you will get marks that skip if it is round the marks should be solid – down and dirty quick check….

Back to the electrical problem on my bomb—

Emergency flashers do not work along with the head lights.. Again checked all of the fusible links. I’m going to try to attach a photo/scan of my wiring diagram. At this time I have that under hood fuse holder all taken apart. Needless to say all fuses and fusible links were checked today and are good, in the under hood panel. The wiring diagram is showing something that looks like a fusible link symbol and is labeled ‘FL MAIN 2.0L’ this is the first symbol from the battery. On the wiring diagram this is the only item between the battery and the flashers and head lights etc. But this is as drawn but not as built. In the fuse panel there appears to be a relay that is in between the battery and flashers and head lights etc. I have been unable to remove this relay, any ideas on removal, the relay is fairly well boxed in and hard to get to, looks like a Toyota special tool is needed (SST). All else in that fuse panel must be OK as I’m still getting power to AM1 & AM2. I’m going to continue to check out this fuse panel and try to by-pass the mystery relay (I can find no place in the FSM that calls out this relay)

 

Good luck man. I am actually trouble shooting my rig right now too. Similar problems, but haven't dove in as deep as you.....yet.

 

Yup, that's the same schematic I've got. I've got the whole TSRM for an 88 in searchable PDF format if you'd like a copy.

When this voltage drop occurs, voltage measured at the battery posts drops as well?

My guess is something is acting as a sort of thermal switch. Everything will test fine until placed under a load, causing an open condition rather than some sort of short.

Is it safe to say that turning the headlights on also causes your voltage drop as well? They would work otherwise right? I would do continuity check of the headlight circuit starting at the battery posts all the way to one of the headlight bulbs. Then turn them on (triggering the open condition) and perform the check again, that power has to be stopping somewhere along that circuit.

 

I went out and took a look at my rig. It's an 86, but there is only one relay on my main fuse panel and it controls the headlights. The relay itself appears to be a SPDT, but operates as a SPST, because only the outer 4 pins on the relay have wires in it's socket.

It did come out pretty easy though. It's secured in place with a little locking tab on either side of it. Get something pointy to stick in there to hold them open, and it should just unplug.

 

Ok looks like I will trace and ring out all of my wiring, gee I hope I find the trouble without having to check all the wires, may be better to build a new harness. (just kidding)

The photo that you sent me, is that the relay on the fuse panel under the hood?

Would like a copy of your pdf wiring diagram. proteus1@hughes.net

Tomorrow I will start at the under hood fuse panel and trace and/or ring out as many wires as I can, starting with head lights and warning flashers, needs to be a spot that is draining voltage.

Hey CHALLENGE stay with us, a7mgte has come up with some good ideas. We can all learn something...

WALT

 

Yeah, that's the relay under the hood. I found that picture online though...I could only wish mine was still that clean. The TSRM is 51mb, so it probably won't fit in your email box very well, so I uploaded it HERE for you...and whoever else wants it. This manual is for the 1988 truck / 4Runner.

Because your entire electrical system is failing at once, the problem has to be near the battery. Positive or negative...one of them is failing under load. When you get that headlight relay out, if you jumper it's socket it will remove all of the wiring going to and from the switch in the cab from the equation. If you're lucky the headlights wont come on when you do this. Making it much quicker to check the circuit from the battery to the right front headlight since everything should be within 10" of the battery at that point.

Looking at the schematic (page 1466 in the PDF) it appears that the headlight relay supplies positive power the the headlights, and the switch on the column provides the ground depending on if you want high or low beams. This means that you will also have to provide a ground to the headlight to fully remove the section of the circuit that goes into the cab.

The wires on the relay socket that would need to be jumpered are the red wire with a blue stripe to the red with a green stripe. Then ground the right front headlight through the red wire with a blue stripe and cross your fingers and hope that headlight doesn't come on. Because if it doesn't come on now, you know you're only a few minutes from finding out why. If it does light up...well, then threaten to buy a chevy somewhere the truck can hear you say it. Hopefully that'll scare it into working.

Keep in mind, that if the headlights do come on when you jumper that relay socket it will arc a little and you'll want to use a wire large enough to power the headlight, because it's gonna come on when you fix your problem.

If that headlight doesn't come on, and the circuit still tests good but has no power then the only place left for it to have failed is at the primary ground...So start checking in the other direction until you get back to the headlight again. The good news about the ground circuit is it's a very fast one to check at least. The negative cable should bolt to the engine somewhere. And usually somewhere near the firewall there should be a (commonly braided cable) wire connecting the engine to the chassis.

 

'then threaten to buy a chevy somewhere the truck can hear you say it. Hopefully that'll scare it into working.'

VOODO ? ? does it really work ? ?

Got your Service Manual PDF this morning, thanks very much! !

[IMG]file:///C:/DOCUME%7E1/WALT/LOCALS%7E1/Temp/moz-screenshot.png[/IMG]

 

I dunno....it does seem these trucks have a limited vocabulay though, because they only seem to respond to lots four letter words.

 

Well I must have said the right four letter words - It started and is running.

Big dumb move on my part it was the engine to firewall ground..
Made up a new ground and installed it and it started right up, now I have to put it all back together.

A big thanks to all that helped out..

A special thanks to a7mgte for all of his time and effort


WALT

 

Glad to hear its up and running again. It never fails to amaze me at how often use of the word chevy makes a toyota get off its rear and work like its supposed too.

My name's Dan by the way.

 

Hello Dan

What got me was that about a week ago I took one of my battery jumper cables and connected one end to the engine block and the other to the firewall, and nothing got better. So I figured that my ground was good. In your last post you kept talking about grounds so I just made up an new one and hooked it up and all got better.

Again thanks for all your help ! !

WALT

 

Quick question: I am having similar problems and following your posts here. I just realized that I don't have a "check engine" light coming on in my dash. Should there be a check engine light coming on? This may sound like a dumb question, but I bought the vehicle in the non-running state it is in.

 

Challenge

When the Ignition switch is in the run position all of your gauges should be on line, as to the check engine light I think that only lights when you have a problem. Do some of the same things that I did along with a7mgte, try warning flasher, head lights etc. If the check engine light has been reset it will not light until your next problem.

Did the seller give you any idea why the car does not run or was he in the dark.

WALT

 

I got the 4runner at an auction. I wasn't able to talk to the owner. I am actually in the process of going through your thread and checking everything in the same order. It acts like it wants to start. I consider myself a pretty good mechanic, but this EFI thing is completely new to me. I have the big Toyota manual and I am just about to go to the garage and start testing each circuit one by one.