Co_94_PU

iTrader: (-1)

You need to.be very certain about that "pro" probing technic, which I'm not knocking that's the way but I didn't describe it at all, because the next thing I'm gonna say is..

That relay is ˟˟˟˟. However go ahead and hook it back up by itself with the alligator clips and energize the coil and check for voltage on that pin that's not getting power (that's the voltage out to the starter!).. If it's not getting voltage we can't make it worse by taking its cap off and getting eyes on the mechanism, is it broke, is it corroded, is it ...

..
The other way to do that probing test you did with the pin is to run leads between the harness and the relay, such that you can still see the ends of the plugs via spade connectors and or an assortment of alligator clips. And you can get probe tools onto it that way.
​​​​​

GreyYota87

Yea probably not the best way to probe but it works lol. Redneck style! So pin2 sends power out to the starter. What feeds pin7 power on the N2 plug, because I also have no power there.

I'm still at a lose for why the relay works when direct to battery, but inline with the harness it fails to work. I'll take it apart and see what's going on either way....

I'm worried I'll replace the starter relay and still lack power on Pin 2 on the relay and pin7 on N2 plug.

Co_94_PU

iTrader: (-1)

Starter relay plug (F), for completeness, this is looking at the face of the harness end.. The pigtail on the relay would mirror this (pin one on the right.


At this point if it's not working I don't feel bad telling you to bypass the starter relay and add an external one to do the "relay mod"

But I am however curious what's going on in your Toyota relay!

GreyYota87

I'm going to go pick up a 30amp relay and do a temp setup with some lengths of wires and spade connectors just plugged into the harness and see if that changes anything with the relay. Is their a certain relay other then that ugly ford one I should be using?

If you give me about 10/15 minutes I'll have some pictures loaded up of the inside of the relay. Maybe you will see something that is out of whack!?

And if this new relay isn't the cure for my issue....what else am I missing? I'm still a bit worried about pin7 not having power, and don't understand where that would get it's power source.

Co_94_PU

iTrader: (-1)

Power in from the switch on pins 3&4, ground thru the clutch pedal switch or cancel switch on pin 1 (bypassed), and power out to the starter on pin 2.

I'm at a loss also. I guess there could be some follow up questions.

Does the relay not even click when it's plugged in? (The reason I asked you to do it with the starter wire unplugged is so it wasn't drawing any current, this prevents it from having voltage drop across the "dirty" contacts of the ignition switch or the internal reed switch of the relay.)

with the relay on the test "bench" shown above with the aligator clips. If you apply power to 3 and ground to 1 and measure resistance across 2 & 4 it shows an open circuit (OL)?

Co_94_PU

iTrader: (-1)

Highlighted in red is the link between the relay output (connector F pin 2) and the N2 connector..

After N2 there is a splice that branches off to the cold start and starter.

Pretty sure RAD/Ray has an annotated version of that schematic in the sticky thread which I couldn't do justice to on my phone's image editor.

GreyYota87

Correct, the relay does not click when attached the the vehicle harness, but when on the "test bench" it open and closed. I opened up the relay and everything looks to be in great shape. Once opened I got a better idea on how the relay works. While having someone turn the key into the "start" position I pressed in the plunger on the relay and it started to turn over! Finally something out of this thing! But something is telling this relay not to close the circuit on it's on own...maybe it's just worn out from being 30 years old! I'll be trying a different relay that I'll temporarily wire in to see if it turns over.

Also in pressing in the plunger (not the best term lol) I did finally get power down to my N2 plug and pin7 got power to it. It looked a bit weak and only about 8volts, I'll double check tomorrow on that. With what I've seen and tested, and my very limited experience I think it's a bad relay...what's your input on it?

GreyYota87

I'll test this tomorrow morning and see what I get. I should be getting some resistance between 2 & 4 when powered to pin 3 and ground to pin 1. But how much resistance is to much, and how much is to little?

Co_94_PU

iTrader: (-1)

Great that is really clean and (likely) not the problem..(There is a siide case where maybe, your bypass of the clutch safety doesn't carry enough current to power the coil of the relay which you can test by pressing the clutch to the floor and giving it a better ground.)

You very likely have the classical wiring fault, which is a side effect of the cost cutting step in the engineering process (an engineer eliminated a wire and saved Toyota a few dollars times a few hundred thousand vehicles ka'ching!) all the current used by the starter solenoid is routed through the ignition switch. This causes the reed switch in the ignition switch to arc, pit and generally become gunked up such that it can't provide enough current to close the relay.

You can test this by wiring up the relay with the extension wires I was talking about above but leave off pin 3, pin 3 you want to connect with a length of wire you can touch to the battery or another reliable power source and the should close just like it did on the test bench and the starter is going to turn. (EDIT: the starter only turns if you have the key in Start position, but it's going to click closed )

So on the back of the ignition lock cylinder is the ignition switch, you can attempt to disassemble and refurbish/clean it or order a new one. Just be aware there is a spring in there and some easily lost parts.

GreyYota87

https://www.yotatech.com/forums/f199.../#post51947160

Is this the flaw you are talking about? I've been reading into this and was wondering if this was the issue. I'll give it a shot tomorrow and see if it is the fix for my issue. I did have 12v at both pins 3 & 4 but I'm guessing that when it enters the relay it could be dropping and not allowing it to function properly and close the circuit?

Also, if that is the same flaw you are talking about I just want to clarify that it is pin 4 and not pin 3? You mentioned pin 3 and the other post mentions pin 4.

GreyYota87

Well I couldn't help myself and I got back outside with the truck. I put the stater relay back together and made a few small jumper wires. I hooked up pins 1-3 with short cables and on pin 4 I ran a wire straight to battery and still had no luck with getting the relay to click....Finally after a few minutes I thought about running the starter relay straight to ground and power hooked up via the harness. So pins 2-4 are jumped to the harness and pin 1 on the relay socket is jumped straight to negative on the battery post. BOOM! I cranked the key over to start and the truck turned over.

I'm going to clean up all the wiring and do this temporarily until I know the truck is going to run. I do wonder though what else is grounded through that same ground and if those things are affected by it as well. If that be the case, can I run a new wire and tie it into it's original location to fix this damaged wire? If this same ground is also grounding other things, what is grounding off of it?

GreyYota87

Looking at one of the pictures you posted I can see that the Black/Red wire (ground) is also used by the clutch start cancel. I have the two wires down near the peddle tied into each other since the switch down on the floor and the switch on the dash is no longer in the truck. I'm assuming that since the ground is not working for the starter relay, the ground is most likely not working for the other two things on that wire. Even with the truck in neutral, the truck will only turn over if the relay is ground straight to battery.

If I'm ok with just running straight to battery for the ground I'll do this until I can replace the wiring in the harness where it is damaged!

Co_94_PU

iTrader: (-1)

Refer to the schematics. It's the same schematic just mirrored. Odd pins are the coils, even pins are the switched power.

Having you connect the #3 pin direct to power with jumper wires is intended to prove the clutch bypass is good and the ignition switch is bad. If wiring it up like this doesn't work, the next step is to switch it around and use the switch for power and a new clean ground and prove its the clutch bypass and not the ignition switch.

​​​​the ground (clutch wiring) is suspect because the COR works and the starter relay doesn't while the starter is disconnected.

Bingo! Your clutch safety system bypass is at fault. Reference to the schematic and we see the two clutch safety switches are certainly. I'll have to dig out the full schematic (there is one at the back of your FSM) to see what else connects via that ground point and which ground point it actually is, however it could be as simple as your bypass is at fault and the rest of any devices on that ground point are OK.

Or maybe you just need to scuff up the ring connection at the point it attaches to the body.

(Edited for premature send)

Co_94_PU

iTrader: (-1)

Ground is G, in the left kick panel. It's lots of devices on it.. One that stands out is the EFI main relay, this one "turns on" the ECU and would explain your injectors not fireing.


Get out your wire brushes and clean up ground points. You need to do the left kick panel for certain, probably the fender to battery, and it wouldn't be a bad idea to just do as many as you can find.

Scrub the ring, the body, the bolt and nut threads. It should be clean bright shiny metal to the best of your abilities.

GreyYota87

I've tried starting the truck a few times and it tries to fire up. I till have the wire jumped from ground on the battery. I'm going to be looking into the harness and see what I can find. Strange that the black/red wire grounds out all those other circuits, but I'm not having issues with them. I'll check all the grounds again, but I think I got them. Always worth checking over though! The few attempts I made to start the truck it would fire for about 30 seconds and shut off. I pulled a couple plugs and they are wet, but smells like bad gas so I drained the entire tank...I had added 7 gallons of fresh gas...so now that the tank is empty I'll fill with fresh gas and see if that helps....still need to figure out the other issue with the OX sensor though..

I also noticed I have a check engine light so I pulled the codes. It looks like it's flashing a #21. I looked into what it is, and I'll try my best to test the sensor. If the OX sensor is working fine, does that mean it's in the harness somewhere like the ground wire for the starter relay?

Co_94_PU

iTrader: (-1)

The code 21, no O² signal isn't relevant at this point since it starts up in open loop mode and stays there until operation temperature is reached.

​​​​The 30 seconds thing is a clue.. Does it actually run for a few seconds and shut off, or does it only sort of want to fire?

You should check the fuel pump runs when the VAFM air vane is pushed open by hand.

You should still check the injectors are firing.

And maybe check the ECU is getting power during cranking on the wire from the efi relay.

GreyYota87

I guess it doesn't run, it only sort of wants to run. I'll take the filter off and push the vane by and see if the fuel pump turns on. It seems like it only turns on while holding the key in "start" so that leads me to believe it's not staying when I release the key.

Do you check for the injectors firing by doing it with the stethoscope? I'll check all the power on the wire for the EFI relay as well. Am I correct in saying those are the +B1 and the +B on the ECU plugs?


EDIT

I checked both +B1 and +B and both have 12v.

Co_94_PU

iTrader: (-1)

Good, that is both switched input to the ECU so ground G isn't completely at fault and we can probably blame the ground issue on the clutch safety bypass.

Yes I check injectors with the mechanics stethoscope, these are just a few dollars at your local harbor freight, you can get by with a long screwdriver or wooden dowel. A large part of the signature sound (tick tick) of the 22re is in fact the injectors slamming shut.

The fuel pump should be powered by the switch in the VAFM when it's flowing air, during start up the COR runs it but shuts off shortly after the STA signal stops.

You can always try spraying starting fluid into the throttle body, if you can start and keep the engine running by pulsing the spray it's certainly a fueling issue.

If the pump runs, the injectors get pulses to open (and assuming it's just a fuel issue) you got a problem with the pump sock (in tank filter), the fuel filter, clogged injectors, or maybe even your add on fuel pump. All of these can also combine small flow issues into a big enough issue for it not to run. (The are also edge cases where the fuel lines are crushed, rusted on the inside, or just full of gel.)

scope103

Not that it matters here, but on my '94 3VZE, the fuel pump is only powered through the COR. The COR has two coil windings; one uses the STA signal to close the COR, the other the FC signal from the VAF to keep it closed. So "starts and runs a few seconds" can be caused by a failed FC winding in the COR, but much more likely a problem in the wiring or the VAF.

The good news is that all of this is trivial to check. If jumpering FP to B+ (bypassing the COR) doesn't change things, then the problem is not in the VAF-COR circuit.

Co_94_PU

iTrader: (-1)

Circle takes the square..

Same wiring in the pre 88 vehicles, two coils in the COR, one tied to the ignition one to the VAFM.