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92_gt
08-11-2014, 09:48 AM
Ok guys I'll try to keep this short. My 92 celica sat for a year, put her on the road yesterday. She was running like a dream until I was going through the local tunnel. Turned the headlights on and bam, car shuts down. Check engine light briefly came on then that was it.

Cranks no fire. No check engine light comes up when I go key on, so I'm thinking it has something to do with the ecm. Can't even get flash codes. I replaced the engine main relay and still nothing. (just assuming that's the one for the ecm) Checked every fuse I could find in the car and they're all good. Is the Engine Main relay under the hood the only one linked to the ecm? I have a repair manual for the car but it doesn't really help. Really hope the ecm isn't fried... Anyone know where the ecm is in these things? I'm gonna see if I have power going to it or not and go from there. Obviously I've got a short somewhere that I need to find as well.

Any pointers would be great.

Nitro_Alltrac
08-11-2014, 11:04 AM
The ECM is under the center stack, bolted to the floor beneath the radio/cup holder. It's probably easiest to access it from the passenger side. Pull the carpet back up under the dash where it goes up under the front of the center console.

I had something similar happen to mine several years ago. I would randomly hit a bump and lose all power in the car. It ended up being an internal short in the starter. Sounds like you've got power through most of the car though.

CollapsedNut
08-11-2014, 06:41 PM
Logically, if you have a short to ground in the head light circuit it should have blown a fuse so more than likely you've got a short with another wire on the engine side. Try removing the fuse for the headlamps and see if you get spark. There are tests you can do on the igniter and distributor as well to determine if they are good, your Chilton or Haynes book should cover them. Look at the circuit for the igniter and then do voltage drop tests on the wires to check for opens.

92_gt
08-11-2014, 08:49 PM
Are the ignitor and fuel pump controlled by the ecm? Just wondering cause I don't think the ecm's powering up, or its fried. No engine light when key on. I may be wrong. I don't have the covers for the 2 fuse blocks that are in the car, so I don't know which fuse and relay is for what. I do know what's what in the fuse block next to the battery. Tried it with the headlight fuses pulled, nothing. I replaced the engine main relay thinking it was ecm related, are there any other ones I should be checking? EFI main?

VavAlephVav
08-12-2014, 12:42 AM
here's a link for the EFI checkout procedure to test the various ECU circuits. for the 5sfe( idk if that's what you have)
http://bgbonline.celicatech.com/93celica/fi/voltohmmeter.pdf
It would be better if you found this section in the book you've got to be sure it's the right year. Sometimes the pins on the ECU change from year to year but the color wire for each circuit seems to stay the same.

what you need to do is go to the ECU mounted up under the passenger side of the dash and use a volt meter with needle probes to poke(carefully) through the back of the plug.
the chart tells you what the voltage should be with the key ON, and there are a couple of them you'll need to test with a friend cranking the starter.

Let me say that I read it in the fsm several times, and still didn't see it right away, but Most of the Time the Problem lies in a Bad Connecter. unless somebodys smashed up your wires somewhere. If you had a "short" you'd have a blown fuse, If you have an "open" shit just shuts off. There are also some readings where you can test the resistance of the circuit with the battery unhooked, and the ecu unplugged. then test the wires from the ecu plug to show a break in the wire or connector(most likely).

also are you sure the Check Engine Light even works? maybe the bulb is burnt out?
either way if the ecu is bad you should be able to go through that procedure one at a time to prove it.
trying to see wtf is going on with your head crammed up under the passenger side is the hard part.
:amuse:

CollapsedNut
08-12-2014, 01:08 AM
Even with a bad ecu you'll have lights etc when you key on. You're not getting power to anything it sounds. Maybe sure both battery cables are tight and clean, ground to chassis is tight and clean. There is a main fuse under the hood, can't say which but if you inspect them you'll see a blown one, should be an atc fuse around 90 amps.

CollapsedNut
08-12-2014, 01:10 AM
I mean pal fuse, not atc

Murgatroy
08-12-2014, 01:10 AM
Even with a bad ecu you'll have lights etc when you key on. You're not getting power to anything it sounds. Maybe sure both battery cables are tight and clean, ground to chassis is tight and clean. There is a main fuse under the hood, can't say which but if you inspect them you'll see a blown one, should be an atc fuse around 90 amps.

Reading comprehension pwns you.

No CEL. Everything else comes on, how else would the car crank, but not catch?

CollapsedNut
08-12-2014, 01:11 AM
I'm from nc. Sorry.

VavAlephVav
08-12-2014, 05:15 AM
that's why I told him to check the bulb. does it even light up when you turn the ignition?

id say you could get a scantool from wherever but also, if you're handy with the computer at all you can use your laptop and find a torrent called techstream which is the software from Toyota TIS. then you need a $25 obd2 to usb plug, and a $16 obd1 to obd2 adapter.

https://techinfo.toyota.com/techInfoPortal/appmanager/t3/ti?_nfpb=true&_pageLabel=ti_home_page&SMENC=ISO-8859-1&SMLOCALE=US-EN&SMAUTHREASON=0&SMAGENTNAME=%24SM%24mT%252bGLraBu9CwUVnZg4mEDzB2ky sT90hgbwsWgdZzNOc%253d&TARGET=%24SM%24https%3A%2F%2Ftechinfo.toyota.com%2 F

http://thepiratebay.se/torrent/9618277/Toyota_Lexus_Scion_TECHSTREAM_TIS_9.00.025_%281.20 14%29

http://www.ebay.com/itm/MINI-VCI-16-Pin-OBD2-OBDII-Car-Diagnostic-Scanner-Tool-for-TOYOTA-TIS-Techstream-/400734780965?hash=item5d4da77e25&item=400734780965&pt=Motors_Automotive_Tools&vxp=mtr
http://www.ebay.com/itm/Diagnostic-Tool-OBD1-to-OBD2-convert-adapter-cable-for-Toyota-17-pins-convertor-/321080285967?hash=item4ac1e05b0f&item=321080285967&pt=Motors_Automotive_Tools&vxp=mtr

compared to what you get out of the deal that's not a bad price.

92_gt
08-12-2014, 07:02 AM
here's a link for the EFI checkout procedure to test the various ECU circuits. for the 5sfe( idk if that's what you have)
http://bgbonline.celicatech.com/93celica/fi/voltohmmeter.pdf
It would be better if you found this section in the book you've got to be sure it's the right year. Sometimes the pins on the ECU change from year to year but the color wire for each circuit seems to stay the same.

what you need to do is go to the ECU mounted up under the passenger side of the dash and use a volt meter with needle probes to poke(carefully) through the back of the plug.
the chart tells you what the voltage should be with the key ON, and there are a couple of them you'll need to test with a friend cranking the starter.

Let me say that I read it in the fsm several times, and still didn't see it right away, but Most of the Time the Problem lies in a Bad Connecter. unless somebodys smashed up your wires somewhere. If you had a "short" you'd have a blown fuse, If you have an "open" shit just shuts off. There are also some readings where you can test the resistance of the circuit with the battery unhooked, and the ecu unplugged. then test the wires from the ecu plug to show a break in the wire or connector(most likely).

also are you sure the Check Engine Light even works? maybe the bulb is burnt out?
either way if the ecu is bad you should be able to go through that procedure one at a time to prove it.
trying to see wtf is going on with your head crammed up under the passenger side is the hard part.
:amuse:

This is exactly what I'm looking for thank you! I checked out the rest of that site (complete wiring diagrams for 90-93 celicas) and it looks like that's going to be my bible throughout this ordeal.

92_gt
08-12-2014, 07:03 AM
that's why I told him to check the bulb. does it even light up when you turn the ignition?

id say you could get a scantool from wherever but also, if you're handy with the computer at all you can use your laptop and find a torrent called techstream which is the software from Toyota TIS. then you need a $25 obd2 to usb plug, and a $16 obd1 to obd2 adapter.

https://techinfo.toyota.com/techInfoPortal/appmanager/t3/ti?_nfpb=true&_pageLabel=ti_home_page&SMENC=ISO-8859-1&SMLOCALE=US-EN&SMAUTHREASON=0&SMAGENTNAME=%24SM%24mT%252bGLraBu9CwUVnZg4mEDzB2ky sT90hgbwsWgdZzNOc%253d&TARGET=%24SM%24https%3A%2F%2Ftechinfo.toyota.com%2 F

http://thepiratebay.se/torrent/9618277/Toyota_Lexus_Scion_TECHSTREAM_TIS_9.00.025_%281.20 14%29

http://www.ebay.com/itm/MINI-VCI-16-Pin-OBD2-OBDII-Car-Diagnostic-Scanner-Tool-for-TOYOTA-TIS-Techstream-/400734780965?hash=item5d4da77e25&item=400734780965&pt=Motors_Automotive_Tools&vxp=mtr
http://www.ebay.com/itm/Diagnostic-Tool-OBD1-to-OBD2-convert-adapter-cable-for-Toyota-17-pins-convertor-/321080285967?hash=item4ac1e05b0f&item=321080285967&pt=Motors_Automotive_Tools&vxp=mtr

compared to what you get out of the deal that's not a bad price.

I know the bulb COULD be burnt out, however right when the engine initially died the light did come on until I went key off to try and restart it while I was coasting through the tunnel dead...

92_gt
08-12-2014, 09:35 PM
Very little progress made today. After printing out some of the wiring diagrams from that site, I realized that the Engine Main relay doesn't really tie in anywhere with powering the ECU. So I checked the EFI main relay. I have 12 v constant on one terminal, and nothing coming out the other side even with key on. Also verified this by not getting any power at B+ on the test port. Looking at the diagram it says the black and yellow wire coming from the EFI Main Relay should be going to the ECU which also run power to the test port. Not sure if I'm going about this the right way, but I just want to check as many things under the hood before digging out the ECU.

In short, I'm going to replace the EFI Main Relay next and see if that solves anything.

I also noticed that in the repair manual I have for the car, in one of the ECU diagrams it shows the headlights and window defogger being linked to the ECU somehow... I could see this maybe for the defogger cause I know it's on a timer, but the headlights...?

CollapsedNut
08-12-2014, 11:06 PM
I'm not sure about the EFI relay exactly but if it's like any other relay you need to make sure you have power in the position that turns it on, relays have 2 voltage inputs. Google something like "how to check a relay" if you're unsure. You may know this and I wish I weren't so brain dead from work so I could help more, but basically make sure you have your switching voltage or else the relay wont let power go through it. Check the switching circuit.

CollapsedNut
08-12-2014, 11:07 PM
Also if it its just a normal black square relay under the hood just swap it with another one like the fuel pump relay or something and see if it works, all those relays are the same.

VavAlephVav
08-13-2014, 03:27 AM
...well swap it with another Uneeded relay, like the one for the AC.

also ive found that when you take those things out you need to dismount the whole relay box assembly and use small screwdrivers to separate the base everything is plugged into from the case like this guy shows for a camry here
https://www.youtube.com/watch?v=VfLoucJRF38
He's doing the main fusible link for the ALT but if you want to takeout the relays you do the same thing.

KoreanJoey
08-13-2014, 05:40 AM
Both EFI Relay and EFI fuse check out?

92_gt
08-13-2014, 07:15 AM
Both EFI Relay and EFI fuse check out?

EFI fuse checks out, picked up a new EFI relay today. At work now so I'll put it in tomorrow. Hoping for the best...

As for swapping it out with another relay, the EFI relay on this thing is it's own special breed. Its round with a different pin configuration than the only other round relay in the box. Of course.

92_gt
08-15-2014, 09:50 PM
Update. Don't know how I missed it but something's popping the AM2. Guess I gotta trace down the short and go from there. Been looking at a few diagrams, every one seems to be different as to what the AM2 is linked to.

92_gt
08-15-2014, 11:36 PM
While diagnosing I tried disconnecting the distributor and bam, AM2 doesn't blow and the engine light comes back. Did the resistance checks for the pickup coil and the primary and secondary resistances and they all checked out ok, but I guess there's an internal short somewhere in the distributor.

VavAlephVav
08-16-2014, 12:59 AM
what I am finding is the ignition coil can be bad even though the wires ohm out right.(the insulation could leak) and the distributor itself can send bad signals even if the pickup coils test good.
and getting ignition parts from the junkyard is a bad idea... :)