87 GTE no power to "EFI Main" relay

[Saavedro88]

Since the Electrical specialty section is closed, I figured this was the best place to put this. My 87 Won't start, I'm not getting fuel. I've done a bunch of testing over the last couple days, but I'm not very good with electronics, but so far what I've come up with is this: When I jumper the fuse panel terminals as though the EFI relay was working properly, it starts fine. But with the relay in the panel (stock one AND new one) I get no fuel. As far as I can tell, I have no power coming into the coil side of the relay. My Hanes manual says that this side gets power straight from the ECU. I'm waiting on my friend who is bringing over a multi-tester and I'm gonna ohm out some wires, but in the mean time, I figured I'd ask, WHY would my ECU NOT be sending power to the relay?

 

[Nick M]

I don't have an 87 EWD, but the 89 online should be about the same, if not exactly the same. The computer energizes the relay, it doesn't supply switched power. The switched power is fused. If you can jump the relay, the ECU is not supplying power, or you don't have a ground. If you can, check to see that the white wire with a black stripe has continuity to ground. Make sure the power is off in the car before you do this.

 

[Saavedro88]

I'll check the online TSRM, but in my Haynes manual the 87 has it's own diagram, and then the rest of the years are all the same. I dunno why.

Right, what I'm saying is, why wouldn't the ECU energize my relay? The actual power to the switch side comes from the EFI fuse. What I was wondering was, what would be some reasons the ECU would see a reason to not supply that power? Is there some sort of protected mode or something it can go into?

I'll check the ground in a second, but what I've done so far is have a test light (that does go to a good ground, it lights up when I touch either side of the EFI fuse) in the wire coming from the ECU, and when I turn the key, it does not light up.

Also, I tested the continuity of the Black w/ Orange stripe wire from the fuse box to the ECU, I had good continuity.

---------- Post added at 06:56 PM ---------- Previous post was at 06:49 PM ----------

Ok. White w/ Black wire has good conitinuity to ground, and the black with orange wire has no short to grounds.

 

[Nick M]

Does the check engine light come on when the key is in the on position? My thought is no power to the ECU. I will have to bust out the 850 manual to see why it wouldn't turn on.

Have you gone into the kick panel yet? You can check these to start.

http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?S=FI&P=50

http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?S=FI&P=51

The second one tells you where to check the M-Rel wire.

edit: The ignition tells the main relay to activate. So the ECU won't turn it on without an ignition signal. So do those voltage checks including ignition with the key on. I think you will find that out of spec.

 

[Saavedro88]

Ok, I will have to check this tomorrow, My friend left with his multi-tester already.

But one thing I just thought about that you should probably know, is that there are a few sensors unhooked right now, two sensors on/near the thermostat housing and what I think might be the oil pressure sensor. I don't know where the oil pressure sensor goes, and the two plug-ins for the cooling sensors are broken. Would those cause this issue?

 

[Nick M]

Those are correction factors for EFI. You are going to make me get the book out again for fail safe. I am certain they do not create a start inhibit mode.

 

[Saavedro88]

Lol, sorry dude. I didn't figure they would, but it couldn't hurt to ask right? I'll check it out tomorrow morning.

 

[Saavedro88]

Those TSRM pin-outs are completely different from what I have. :icon_conf I have significantly less wires going into my ECU and in different places... I'm gonna keep trying but I don't have anything that tells me where voltages or grounds are supplied.

 

[89supracrazy]

I would check the 7.5 amp ignition fuse inside the left kick panel and check to see if you are getting the voltage the ecu. Make sure the fuse is not blown. It is the 7.5 ign fuse that is on the top of one of these links. Also take notice of the 30 amp fl am2 fuse that feeds the ignition switch. Check that one also. Good luck.

One more thing, I have bought a main relay at advance auto before and it would not work. It would plug up and it also look the same but it would not energize. So before ruling anything out check the voltage at the main relay plug.


http://www.cygnusx1.net/Supra/Library/TEWD/MK3/manual.aspx?S=Main&P=036


http://www.cygnusx1.net/Supra/Library/TEWD/MK3/manual.aspx?S=Main&P=032


http://www.cygnusx1.net/Supra/Library/TEWD/MK3/manual.aspx?S=Main&P=33

 

[Dirgle]

First thing I would do is ditch the Haynes manual those things are worse than helpful they are dangerous. Not sure if they have been changed in recent years but the last one I saw tried to cover to many generations of the supra. The information was so general and vague I don't know how it ever got approval to be printed. Continuing to use it will only confuse you.

Next just to verify a few things. If you remove the EFI relay and jumper pin 2 to pin 4 the car starts normal. But if you replace the relay the car turns over but does not start. Is this correct?

Also where did you get this "New" relay?

 

[Nick M]

Those TSRM pin-outs are completely different from what I have.

If you are doing it yourself, you have to have the EWD for your year. Did you check the IGN fuses yet?

 

[Saavedro88]

I would check the 7.5 amp ignition fuse inside the left kick panel and check to see if you are getting the voltage the ecu. Make sure the fuse is not blown.

This was one of the first checks I did.

First thing I would do is ditch the Haynes manual those things are worse than helpful they are dangerous. Not sure if they have been changed in recent years but the last one I saw tried to cover to many generations of the supra. The information was so general and vague I don't know how it ever got approval to be printed. Continuing to use it will only confuse you.

Next just to verify a few things. If you remove the EFI relay and jumper pin 2 to pin 4 the car starts normal. But if you replace the relay the car turns over but does not start. Is this correct?

Also where did you get this "New" relay?

Yeah, I HATE the Haynes manual, it covers every Supra from the beginning of the 1st gen to the last of the 3rd gens. But I can't pull up AllData at my house, so it's all I have to go by...

And yes, what you said about the relay is correct.

I got the new one from Federated Auto Parts. I put it in another Supra and it worked fine.

I actually just came in, because I figured out what was wrong, and you'll NEVER believe it. The 7.5 amp IGN fuse in the kick panel wasn't making the connection across the terminals. :eek3: I checked the fuse with my test light, like 3 days ago, saw I had power across both ends, and dismissed it as the problem. But today, when I tested the power feed from that terminal at the ECU, I had no power. I tore apart just about all of the dash in an effort to find the break in the wire, and I couldn't find anything. So I went to pull the fuse out and it basically fell out in my hand. It was making a good enough connection on the power side to light my test light, but NO connection at the ECU side. :runaway:

So now it runs... Barely. It dies everytime I put my foot on the gas. But that's another issue for another thread. I need to check the codes first.

Thanks everyone for the amazing help! I love this forum OH so very much. :love:

 

[89supracrazy]

One thing at a time until victory. It sounds like the air flow meter maybe is not working. That is the way mine acted when you tried to push the throttle but fix all your codes first and go from there. Do not clean the air flow meter with anything else other than spray air in a can if you decide to clean it.

 

[Saavedro88]

Word.