ECM(s) get no power,Everything else does.

[Cruiseomatic]

If you remember I was swaping a 5sfe for a 3,and it went flawless untill now. All accesories get power but when I go to crank,I get no check engine light,no fuel,or spark. Thing does'nt even turn over. (Unless I hard wire it) Now,the battery did get connected backwards and blew the 100A alt fuse but it was replaced and everything works again. I thought the ECM was fried so I got anouther one,does the same thing. I've checked every fuse and relay I could find and everything checks out fine. There is a green relay " Circuit opening relay" that does nothing when I turn the key on,after looking at a schematic on autozone.com,could this be my culprit?

Is there a relay that powers the ECM I might of missed or fuse?

BTW,Theres a green 2 wire connection on top of the engine we cant find where it goes. There is no sensor for it to connect to,and from the looks,it wasnt on the old engine either.

Can anyone help?

Thanks guys.

P.S. Behind the pasenger kick panel,theres 2 connections it looks like a relay goes there but they are male connectors and empty,Could that be why its doing what its doing?

[toyomoho]

What year again? Auto or manual trans, California or Federal emissions.

I will assume a Gen_3 Auto.

Kick panel may have ABS and door lock relay, heater relay.

The circuit opening relay will only turn on if the engine is being cranked and/or it is receiving a signal from the igniter indicating the engine is running.

Did you check the EFI and IGN fuses, EFI relay?

Battery power to the ECU comes from the EFI fuse which would be a White/Blue wire at the ECU.

What works in the car and what doesn't. Headlights, radio, horn, heater blower, etc. This will help narrow down the circuit issue.

You checked all the fuse and fusible links. Even those behind the drivers side dash behind ashtray (there are two separate fuse-relay panels here), behind drivers and passengers kick panel, all the boxes in the engine compartment.

Most times reversing the battery just blows fuses and fusible links.

These are solid green wires with no stripes, both the exactly same color? Is one a light green and one a green?

[Kep]

If the CEL is off during the POST (when you first turn the key) a message from "Tech Tip Corner" may apply. It was several years ago so I don’t know if it applies to the newer Toyotas or not. However, as long as they still have EFI relays I keep mentioning to check the CEL during POST. Here’s the message:

Relay Runaround on Toyota Models
A faulty main circuit opening relay may cause an intermittent no-start condition on several Toyota models. If you are lucky enough to get the vehicle from the customer when it won't start, try this simple check before you waste any time on complicated diagnosis:
· Turn the ignition to the ON position. The CHECK ENGINE light should be ON.
· If the CHECK ENGINE light is not ON, locate the main circuit opening relay, then make sure you have more than nine volts on the output pole of the relay with the ignition in the ON position.
· If the output voltage is below nine volts, but the input voltage to the relay is equal to battery voltage, replace the circuit opening relay. Its internal contacts are probably pitted and arced, which creates a voltage drop inside the relay.

I've spent more than one day on more than one car, trying to find an intermittent relay. Now I check the CHECK ENGINE light before I do any further diagnosis.

Brad Foltz
Miller Auto Group
Hedgeville, West Virginia


I am pretty sure that he is referring to the EFI Main relay. It wouldn’t take long to check. Page 313 of the Toyota Manual’s 5SFE Engine Chapter shows the EFI Main Relay location in the front driverside of the engine compartment. When you pull the cover off of the fuse box look inside the lid for the locations. Note the EFI fuse as well as the EFI Main Relay. Check both (are the contacts and the receivers clean?). I suspect that the relay is bad and that could contribute to your problem.

Page 216 of the Engine Chapter explains how to check the EFI Main Relay if you are comfortable with using a multi meter. I believe that the relays are under $20.


The Body Electrical Chapter shows the Fuse & Relay Block locations on pp BE-11 and BE-12. The Ign fuse is in the driver kick panel box and the EFI fuse and EFI relay are in the engine compartment box . If you need to, look inside the box covers for a diagram.

Also curious if everything is now 5SFE (Fuse Boxes, cabling, ECM, etc.). If you are mixing 3SFE and 5SFE I have no idea if there might not be different wire routing even if the plugs are the same.

It might help if you post a picture of the loose wires so we can see where they are relative to the engine or kick panel.

Kep

[Cruiseomatic]

Checked the relays again and now the ignition switch is not getting power. One wire is and when you turn the switch on,only thing that comes on is the air bag light on the dash. Everything else that does not require the switch works. Before when the switch did work,Everything worked except starting the engine. Replaced the switch,same thing.

Its a '96 4 cylinder with an automatic.

[Cruiseomatic]

Disregard the last post,A fuse fell out and didnt know it untill last night. Theres a solid black fuse or what looks like one in the fuse panel behind the steering wheel. No current is going through it what so ever,Theres also a little black circuit of some kind on top of it. What are those 2? I have a haynes and chiltons manual but theyre not helping me any.

Thanks.

[Cruiseomatic]

Checked the the circuit opening relay behind the glove box is not getting power,Ive checked everywhere. Nothing. Even got a new ignition switch and still doesnt work.