Well, my truck was running fine. Then it sat around for one of those rare days I don't have to drive anywhere. Then this morning I try to start it and nothing happens. No dashlights, no door buzzers, no dome light, no stereo, no starter...not even a click or anything. After a bit of further investigation, however, I find that the headlights still work (but not the side running lights), the hazards work, and the horn works (it usually doesn't!). I checked all the fuses--they seem fine. Just for the heck of it I checked the battery out and cleaned the terminals. I also cleaned the ground wire, as has been suggested (I think). Still nothing. Any ideas?

Also, where can I pick up a/some wiring diagram(s)? I am having an incredibly difficult time sorting through the jungle that is my electrical system.

 

Did the battery discharge at all? If so you may have a parasitic draw. Disconnect the negative cable and place your DVOM in line with the cable. You should see an amperage draw of a few amps, then it will slowly drain down to say 30 mA when all the capacitors and such drain down. 50 mA is acceptable parasitic draw, but that's still a little high. If your meter still shows an amp or possibly more, then remove the fuses one by one until your parasitc draw goes down to the acceptable level. At that point you've found the offending circuit and you will have to investigate the individual circuit to find out what else is going on.

Other than the parasitic problem, if that looks good, I would take a good look at your ignition circuit. Also, do a voltage drop test on the cables themselves to see if you have high resistance in the cables. Just because a cable looks good from the outside doesn't mean you don't have a problem there. Hope this helps.

-Wrench

 

Thanks for the response. Sorry I'm late in getting to this.

The baterry doesn't seem to have discharged (if I'm not mistaken). I checked it with an electrical tester and it read at something like 12.5-12.6 volts or what have you (I'm sort of new to this stuff). The headlights work and are as bright as ever. I did try to use the tester in line with the negative cable and terminal of the battery and pull fuses but everything looked acceptable. Also, I tested down by the ecu and driver side fuse box to see if I had power there. I had power in both places. I also tried the screw driver on the starter trick and the engine turned over fine. As far as doing a voltage drop test on the ignition circuit, how does on go about that? I'm not entirely sure what the ignition circuit is composed of. This electrical stuff is hard for me to wrap my head around!

Anyhow, I am wondering what the deal is--why would the headlights and hazards come on but not the side running lights or anything else? Also, when I test in certain areas with the ignition turned on or off I do get different readings, so it would seem that the ignition switch (or whatever the key-thing is) works. So it seems to me that some simple thing is wrong with some basic power source somewhere, but danged if I can figure out what it is. I gotta get this car running or I'll be forced to drive a geo tracker!

 

then does it crank with the ognition switch? or only when you jumped the terminals on the starter?

 

Only when I jump the terminals. Ignition switch does nothing. I get no heater/or ac power, no radio, nothing. I've heard stuff about the solenoid, but I imagine that's not the problem because it doesn't seem like power is getting there anyway. But I really am new to this thing, so I could be mistaken.

 

sounds liek the ign switch is bad

 

Yeah, I keep wondering about it. I'll see what I can do. Thanks.

 

I can't tell outright if the switch is bad or not. It seems alright though because when I turn the key from acc to on I can hear a relay click down by the fuse block. I tested the connections on the back of the switch (where the wires join up with the unit) as I changed the switch's position and things looked fairly normal. Oh well. I'll keep on looking around.

Oh, there doesn't seem to be any juice in the tumbler/key sensor. I'll have to see if I can follow that anywhere.

 

replace the switch, at least rule it out... if it isnt cranking then its either the ign switch itself or wiring to the starter.. there isnt extra stuff there... those relays dont mean anything.... there are some relays that power when acc are switched on regardless if they are you starter soleniod or not..... as i learned it, the toyota doesnt actually use an external solenoid liek the ford or similar units have

 

It seems you may have been right. I took the ignition switch apart, and after messing around with it I got power in the cab (that is, everything turned on like it should). Since the switch was so taken apart I couldn't figure out how to work the starter, but it seems like all the power is there. The dashlights and side lights still didn't come on though, but that may be a different problem.

Thanks for the help though, I'll get around to replacing that switch soon then.

 

Hey TMcLeod, sounds like you're on the right path... Just a note on doing voltage drops. In my previous post I referred to testing the cables. I mean the cables that are on your battery. To do a volt drop test, set your DVOM (digital volt ohm meter) on voltage, then touch one probe on the + batt cable, and attach the other probe to the end of the cable that ends up on the starter. You should see roughly 1 volt. This means that you are loosing one volt in that cable. Or you can think about it in terms of the resistance of that cable ends up creating a "drop" of one volt. If you see more than one volt, say 5v or 10v, then your cable has super high resistance. Typically this happens because of corrosion on the battery terminal that leads to the internal corrosion of the cable itself (under the sheath!!). If you ever find a cable like this, cut it open and you'll be amazed at the corrosion inside.

In terms of what works and what doesn't work accessory wise, I wouldn't be too worried about that. Ignition switches do weird things. Test the switch itself, and then continuity of the wires in the ignition circuit. Focus on what starts the vehicle and ignore everything else for the moment. My 2 cents.

-Wrench

 

I replaced the ignition switch and still have no luck. When I turn the key I can still hear a relay click by the fuse block but I otherwise get nothing. As I said before, I took apart the last ignition switch, and by touching the contacts together I was able to get lights and gauges in the cab to function, as well as wipers, parking lights, etc. I am just about completely clueless now. Sorry to keep dragging this on, but I'm getting desperate. I'll try to look at other parts of the ignition circuit, but I'm not too sure what to look for.

 

since it's an older rig, does it have a solenoid? I'm not real familiar with the older toyota engines, but it seems that a bad solenoid would cause exactly the problems you're having (you could even bypass it with a wrench just to get you to an autozone or something)

 

It does have a solenoid, according to the books. Not sure how to check its status though--I'll look it up or something. Also, if worst comes to worst I am wondering about the possibility of hotwiring it or doing something to the effect that I could get the car somewhere without paying for a tow. If messing with the ignition switch before got things to work (so it seemed) is it possible to cross some wires or something and see if it won't start? I am probably getting in over my head here, speculating.

 

I got the truck running finally, but by hotwiring! So just one final question--why would a brand new ignition switch not work? I'm sure I installed it properly.

Well hell. It doesn't matter anyways. I'll sort the rest of it out later. Thanks everyone for your help--I appreciate it a lot! I have to say these are probably the best forums I've ever come across. Thanks again.