zombie87pu

I've got an 87 base model 2wd 22R pickup and over the past weeks I've lost basically everything electrical in the cab. It began with a discharging battery (had to charge it if it had been sitting) and flickering CHARGE light, CHARGE/CEL when braking (linked to taillights?) then constantly on CHARGE light, flickering in-cab lighting (dashboard lights, radio), then total failure. Truck still starts and runs normally.

Only the headlights work, and the CHARGE light is constantly on. Turn signals, brake lights, wipers, radio, all gone.

As part of trying to solve these issues I have replaced/checked the following:

Battery (replaced)
Alternator (replaced)
starter (new-ish, works)
Battery wiring/terminals (replaced both + & - )
Fuse box connections
auxiliary start switch (key still needs to be in run, but turning key to starter position stopped working, now it starts fine)
fuses
Fusible link

Other than the start switch and a tachometer I added years ago, wiring should be stock. I've checked and wire-brushed the engine ground and I seem to have a good frame/body ground by checking for continuity with a multi-meter in a few different spots, but obviously something's not getting through to the cab. I assume it is a short or bad ground somewhere but I'm at a loss for where to look.

I've read about a ground on the passenger side footwell but didn't see anything like that when I looked. Anybody got a pic?
I have the '85 FSM from the interweb but it's wiring diagram doesn't seem to match in a lot of places.

wyoming9

iTrader: (1)

Just what kind of readings are you getting with your Multimeter.

Measuring things is the only way you or anyone will figure this mess out.

If your charge light is on what sort of voltage are you reading at the battery with the engine running.

Just how did you wire this extra start switch??

The ground you are looking for is behind the plastic trim on the door post on the left side

zombie87pu

Sorry I didn't include these before, I was going off of memory (hadn't actually messed with it in a few days). I'll try and cover everything:

The battery currently reads:
12.3v engine OFF
11.89v engine ON, headlights ON
11.99v engine ON, headlights OFF
taken when high-idling (cold engine)

So yeah, it reads low. The battery is brand new but run down from not charging (as shown by the low battery readings when running). Alternator is also new and was tested good. Good ground/continuity on the cables (also new). I've doublechecked and cleaned the Alt connections starter connections, & battery connections.

Start switch is wired as follows:

Battery Positive
10amp fuse
momentary switch (in cab)
starter solenoid trigger terminal (to ground via solenoid)

Just in case I'm getting the name wrong, the terminal I'm referring to is the single small spade connector near the front of the starter. The original trigger terminal connector from the harness was left disconnected and tied off. Either it or the starter switch in the column were not making a good connection, and this at least starts the motor reliably.

This is what I see in the driver's side, I sanded the contact faces of both the wire and bolt visible in the upper left:


No change in situation.

Just for fun, here's the passenger side. I also cleaned the contacts of whatever that is above the emissions box.


Still no change.

wyoming9

iTrader: (1)

Your charging system is not working.Why it could be any number of things

If your ignition switch is not working all the circuits through the ignition switch will not work.

It could also be the fusible links.

The fact it runs is amazing !!

Did you get a bad alternator ??

It happens more and more.

If the voltage gets to low it will shut off.

scope103

No, what the "low battery reading when running" tells you is that you are not charging the battery (as wyoming9 says). You should get about 14.1 volts running. (You should get about 12.6v not running, but that's temperature dependent.)

Check the "Engine" fuse http://personal.utulsa.edu/~nathan-b.../2powersou.pdf, and check for battery voltage at the "IG" terminal of the alternator with key-on. Check for 14.1v on the "B" terminal (the big post) of the alternator while running.

If your ignition switch is in bad shape it might not be powering the Engine fuse through IG-1, which means no power to "IG," which means no alternator. (Heck, IG1 powers most everything else, EXCEPT for the ignition. Sound familiar?)

Nobody wants to spend money, but if you got to the point where you were Franken-wiring around your ignition switch just to throw the starter, losing the rest of the electrical system might not be far behind.

Let us know what you find.

Elwiney

i just encounter the exact same problem on my 2wd pickup 85 im looking at a cable that went out from steering column . missing the other end but dont know exactly where it came from

RAD4Runner

Like Scope says ^^^

Charging system test points/pin-outs explained here.

Engine fuse supplies turn signals, rear window & wiper (for 4Runner). Inspect all wiring to circuit it supplies, including the back-up switch / back-up light circuit here.

zombie87pu

Finally had a chance to test further:

Fuse looks good (not blown, has continuity), but with the key in 'run' (IG1) it doesn't look like I"m getting any voltage to the fusebox terminals for the ENGINE fuse.

zero voltage on IG terminal (red wired spade in alt. plug, correct?).

low voltage, 11-12v, basically the same as what I was getting at the battery when running.

What is the best way I could test for this? Should I just look for voltage at the switch?

Haven't found anything wrong tracing to the taillights and back. I also checked the neutral wire mentioned at the link and it isn't shorted. Even tested removing it entirely, no change in the running/charging behavior (other than being able to start it in gear without pressing the clutch ).

Money isn't so much my concern as just finding the problem. The start switch was an emergency solution (we were moving and had to relocate the truck, nothing permanent), and I really only want to get one more winter out of the truck as a backup vehicle, but I don't know what I should be looking for at this point.

Are there any other common failure points I could look for, based on what I'm seeing?

scope103

You've already done it; the ENGINE fuse is powered directly from IG-1 of the switch, so if you have no power there the switch is almost certainly toast. Here's the diagnostics: http://personal.utulsa.edu/~nathan-b.../3ignition.pdf

From the dealer the switch is about $90. http://www.toyotapartsoverstock.com/...445035060.html From a junkyard, you'll need one in 1984-88 range (see fitment in the prior link).

Good luck!

zombie87pu

So, I pulled out the switch and tested it directly, and it seems to be working fine. It connects AM1 to ACC, IG1 and ST1 at each of the appropriate positions (tested at the connector). Same for the AM2 circuits. It was nice of Toyota to label the terminals!

So then I tested voltage on the AM1 and AM2 terminals in the connector the switch plugs into. Each should be receiving battery voltage all the time. AM2 reads battery voltage when grounding. However AM1 only reads an unsteady ~3 volts grounding to the same spot (I chose the bolt mounting the fuse box).

I still get 12V measuring at the 40A Fusible link for the AM1 circuit. So the problem seems to be between the engine bay fuse box and the starter switch. I have no idea where that actually is routed between those points though. Does this just mean the wiring harness is no good?

scope103

Good job; on-site multimeter work beats my guesses any day.

It doesn't mean the "harness" is no good, but it sure suggests that one white wire is bad somewhere. Of course, it's always best to trace it to where it is bad; something else may be corroded/crushed/whatever at that same point.

AM1 connects through a 16-pin connector ("IA3", pin 14) somewhere above the fuse box by your left ankle. It should be white. Beyond that, I can't help much.

You could consider just bypassing the wire from the AM1 fuse to the switch. Somewhere between IA3 and the switch is a splice off to the starter relay.

zombie87pu

Foul weather and work kept me away from tinkering with this for a bit, but I went looking for the connector you described.
Unfortunately I didn't find anything like the 14-pin connector you described under the dash or in the engine bay; the only connector in the cab I found was the one I tested from earlier, to the starter switch itself.

Here's the view of the steering column and path the wiring appears to take:



I followed it to the drivers side A-pillar fuse box. There's no connector, it wires directly into the back of the box:



It then goes into the firewall, and looks like it comes back out on the Drivers-side inner fender:



It looks like the right-hand branch follows a similar path, passing into the firewall at the passenger side A-Pillar and coming out near the engine bay fusebox. I didn't see any additional connectors other than a small box marked "emmissions control". Unless connectors are inside the fenders, I'm pretty much stumped.

scope103

Sorry; I'm tapped out. The connectors change slightly year-year and due to model differences; my schematics might not match your vehicle.

Does it look like your AM1 wire is white (no stripe)? You might be able to trace that back to the under-hood fuse box. Or, you might be able to bypass it.

zombie87pu

I appreciate the help, for sure, I'm much further towards figuring it out than I would have been alone.

It does look like the AM1 circuit is plain-white wire, slightly larger gauge than the others in the bundle. That's what's wired in to the 40 amp fuse in the underside of the engine fuse-box, and what goes into the switch connector.

There's white wires on the alternator side (my last picture) that might be it, but it might also go around the passenger side. I'm going to try and figure out a decent way to bypass it without tearing up the existing wiring too bad. Will keep y'all posted.

morena67

Subscribed... Good luck...!!!

NewToYota

Also subscribed. I'm guessing this will be of little to no help, but was getting ready to write up my own similar situation. I've owned a 96' 4runner for a little over a week now and for a couple of days after replacing a burnt out dome light I noticed delayed lighting, clock reset etc... Ultimately I lost power to door locks, all interior lights, marker/corner lamps, clock, radio and dash lights. Like yours, my truck still ran and drove perfectly and still had working headlamps. The only alterations to electrical system by previous owner that I can find were an aftermarket stereo. It appears to be clean and professional and left all factory wiring untouched. I scoured over the wiring with no found shorts or inconsistencies. I ended up under the hood at the engine fuse panel for a second time and found my 15A dome light fuse was blown. A new fuse in that location appears to have cured all issues as all is well for about a week and no new signs or odd happenings. I know you are well beyond checking the fuses, but I wanted to share my experience as it's contradictory to Toyota specs and was too similar to your experience to not share my find. I have no idea what was changed that caused these systems to be in the same circuit, but if I find I will update. Best of luck.

zombie87pu

Update on the truck: I've rigged up a temporary bypass for the AM1 circuit by running a wire from the down-stream side of the 40amp fuse in the engine bay box (carefully removing the original pin from its post, leaving it intact), to the ignition switch connector pin that circuit was supposed to end up at.

Doing this gets me 12v to the switch, and powers wipers and turn signals, and it looks like I'm getting power to trigger the alternator (getting a voltage increase to about 13.8 when running). Looks like everything past the switch is healthy. Yay!

This is all pretty jury-rigged, but it's a proof of concept at least.

The last obstacle appears to be the circuit or 'rail' labeled "B" in the FSM. I'm not getting any power to the fuses on that circuit, like STOP, TAIL and DOME. Basically anything getting power from B appears to be dead. This would sort of make sense given it breaks away from the battery just after the 80amp Fuse but before the 40amp.

I don't see any simple way to run a bypass for "B" since it doesn't appear to terminate at a single connector, and I'd probably have to start cutting into the harness.

I'm heading to a junk yard today to see if I can find some replacement harness/fuse box parts, since it looks like whatever is wrong is pretty extensive. As always, any advice or ideas are appreciated.

zombie87pu

Update: While working out a clean way to bypass the AM1 line running from the fuse box across the bed to the drivers-side fender connector, I re-tested the contacts for the 40Amp FLF in the box and noticed something weird:

The + side fuse panel connector for the fuse shows about 1-3 volts between it and the + side of the battery. That contact *should* come straight from the 80Amp fuse to this terminal (inches away) and read zero when measuring this way, but the wiring under the fuse-box suggests it goes somewhere else down the loom, then comes back. Why Toyota didn't run 2 inches of wire between the two fuses I don't know, but they didn't.

Wherever it goes, it's closing a couple volts worth of circuit on the wrong side. Ah hah!

So I removed the existing 40Amp FLF, and bypassed the wiring giving it power from the fused side of the 80Amp FL. I did this with a 40 amp blade fuse in an in-line holder, wired between the fused side of the 80Amp FL and the negative terminal for the 40Amp FLF in the fuse-box. It's ugly but it still has the 40A safety.

Result: Everything now works except the blower, weirdly. The battery is charging at ~14 when running, all lights work, and everything in-cab except the blower motor runs. I can hear the blower relay engage, and the fuses are good, but no woosh. *shrug* Might be related to the mystery short. That can be a problem for another day though, because now I have a running truck. *victory dance*