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Hey folks, I've read and searched my way to some progress here, but solution is still a mystery. Working on Dad's 1990 4Runner, 4wd, auto trans, 3L v6.
At 90k miles, I had swapped the starter. Truck started fine for 2 weeks, normal use. Now having the classic "no click no start" problem. I can hear a single click in the ECU, but no click and no activate at starter solenoid. I pulled the passenger side right kick panel and stuck my face right next to ECU during a no start attempt. one click. I do not believe this type of truck has a starter relay, as it's auto trans. I could be wrong..
Key tumbler had been replaced over a year ago. Also swapped the electrical portion of the ignition switch, no joy. Battery was load-tested good.
I verified that the solenoid, starter motor (and battery) can turn the engine over. I followed this helpful post - basically we bypass the truck's wiring, and go direct from battery to solenoid; https://www.yotatech.com/forums/f199...l#post52367443
Also I measured volts at starter solenoid wire - the female spade terminal that connects to starter solenoid. When key in Start position, I see 12V on that wire.
I cannot shift out of Park unless key is in Run position. And I cannot remove the key unless shifter is in Park and key is turned to normal remove position. I think these tests mean the shift lock override is good. True?
Today after testing solenoid and starter as per #post52367443, it turned over normally, twice. But won't turn over since. Argh. I checked the wire connector, female spade terminal going to solenoid, and squeezed it down a bit, it feels like making good contact with the male connector.
Can I bypass the shift lock override to test? Should I even think of this, since it seemed to behave properly in above tests?
Can I bypass the neutral safety switch to test it? Is that switch under the shift lever in center console / hump?
Any other suggestions of stuff to look at are appreciated, and many thanks in advance.
... Also I measured volts at starter solenoid wire - the female spade terminal that connects to starter solenoid. When key in Start position, I see 12V on that wire....
Originally Posted by alexman
... Can I bypass the shift lock override to test? Should I even think of this, since it seemed to behave properly in above tests?
Can I bypass the neutral safety switch to test it? Is that switch under the shift lever in center console / hump?....
if you have 12v on the solenoid wire with key to STArt, then you have already tested the PN (Park-Neutral) switch, AND the starter relay. The essence of electrical diagnosis is start at one end and work towards the other, not retracing your steps.
But, I suppose, you might have an intermittent problem. Then, when it won't start, put your finger on the starter relay when someone turns the key. If you feel it click, remove the relay and jumper the terminal (as shown in the cited post) to the battery. If the relay doesn't click, remove it and check for voltage on the switching terminal. These tests don't involve lying on the ground or any wrenches.
I had an 88 v6 auto and had an issue that sounds similar to yours, it ended up being the neutral safety switch. have you tried cycling through the gears and starting in neutral?
if you have 12v on the solenoid wire with key to STArt, then you have already tested the PN (Park-Neutral) switch, AND the starter relay. The essence of electrical diagnosis is start at one end and work towards the other, not retracing your steps.
But, I suppose, you might have an intermittent problem. Then, when it won't start, put your finger on the starter relay when someone turns the key. If you feel it click, remove the relay and jumper the terminal (as shown in the cited post) to the battery. If the relay doesn't click, remove it and check for voltage on the switching terminal. These tests don't involve lying on the ground or any wrenches.
@scope103, This truck does not have starter relay in the relay box in engine compartment. Location of the box is the same as the post you referred to, but this version is marked as headlight relay in that position. For fun I pulled that relay, and no headlights. I agree with your suggestion, if I could find the starter relay (if one exists) and put a finger on it during start attempt, I should feel a slight click, and could then diagnose further back through the circuit.
However, I saw info somewhere in the forum that said some versions of this truck do not have a starter relay. I read a few posts on that topic but the method of identifying trucks-without starter relay did not match up with truck I have.
Originally Posted by keycw
I had an 88 v6 auto and had an issue that sounds similar to yours, it ended up being the neutral safety switch. have you tried cycling through the gears and starting in neutral?
@keycw, yes I have tried starting from Park and from Neutral. Foot on brake as if to shift from Park, foot off brake. Shift lock override pressed, and pressed again.
I'm glad it's still failing to start - at least I did not get it completely reassembled, started properly twice, and girlfriend was now driving it for grocery..
I will see if I can measure some volts at neutral safety switch. Any suggestions on what to expect there and how to bypass it for testing are appreciated. That part is $140, I'd like to be a bit more confident in the diag before releasing the cash. Thanks for suggestions!
I had studied that thread prior to my original posting, it was helpful but i'm stuck not finding the relay.. I check the 'List of affected models', some of those pictures show manual trans version - pictures with 'clutch start cancel switch'. I have auto trans. The image of 1990 4R 3VZE seems to be the correct year wiring diag, but I cannot locate what is circled in red with ! and cannot zoom in enough on the diagram to read what is next to it for a clue where to even look.
In any case, I also studied 'fix the starter relay' thread that is provided in #post52368224. Not finding starter relay. Feelin pretty lame but I don't know where else to look. I could post pictures of what I do have: engine compartment relay box, kick panel fuse block, ECU, and/or neutral safety switch, if those things would be useful.
...
Since above writing, I disconnected the nss and measured ohms and volts on the wires inside the connector.
The 2 big blades - one is GND (ohm test and have GOOD continuity between blade and frame of vehicle.) The other blade has 10v when key in Run pos. 10v is suspicious.
A pair of small pins at one end of connector has 12v on one, GND on the other regardless of gear shift position, and the pair at opposite end of connector have no wires present.
The three small pins adjacent to big blades, I find no volts and no GND on these, regardless of key on or off, Park, N or D.. Not sure what it means.
I'm game to cut out bogus wiring and improve starting system performance, if i can be confident about what I'm doing. But so far with info I have seen, I cannot be certain where to cut, and where to reroute.
In any case, thanks for sharing info and having good pics, I've learned a lot from your posts.
You have a current problem. There are two things that bring me to this conclusion. First you reliably (?) get battery voltage when testing the solenoid activation wire with the key in start while it is disconnected from the starter. Second you can reliably start the engine by applying a hot wire to the starter solenoid plug at the starter.
If you back probe the starter solenoid activation wire while it is connected with your volt meter I expect you will see the voltage drop well below battery voltage. This tells you the circuit (wires) aren't capable of supplying the power (volts * amps) to close the solenoid contacts.
You can test this!
Much like is covered in the adding a starter relay thread. Take a hot wire from your fuse block route it through a relay to the solenoid. Place the factory solenoid plug on the relay activation and see if it starts. I'm willing to bet it will.. This is in essence what the other thread is doing in much less detail and in a nonrestrictive reversible way.
CO_94_PU, Thanks for the reply, I think I finally get it now.
I studied the hand drawn diagram by RAD4runner in #post52297396 again. That diag is using a square relay with the commonly labeled terminals. I'm trying to use a 12V 22A relay claimed to be for Toyota 4runner starter, it's round and terminal arrangement is different. Pics below.
Just to be sure that I understand the concept,
high current side is marked by having an open leg
connected leg (#4 in pic) goes to positive batt terminal, with 30A inline fuse
open leg, (#2) it's new 12ga wire, goes to starter solenoid
low current (signal) side is marked by a rectangle box
one leg (#1) takes in the wire formerly connected to starter solenoid
other leg (#2) goes to frame ground or negative batt terminal
Do I have this right? Many, many super-thanks for the handholding!
I quit messing with the old round relay and got one that matched RAD4runner's diagram, I wired it exactly as shown there. I was not expecting relay to be energized when battery connection was completed, but I guess it makes sense. Fixed. Starts fine again. :-)
Many thanks to RAD4runner, CO_94_PU, keycw, scope103 for assistance. Without help from you guys I'd still be swapping parts and scratching my head.
03-20-2019, 05:20 PM
