Where do these attach to?

[Van]

These wires are under the intake runners and I have no idea where they attach, or even their purpose.

Thanks. Van

 

[Dirgle]

Its the ground for the ECU and various other systems.

it goes here:

 

[Van]

Great! Thanks.

 

[radiod]

I had the same question when putting my engine back together. I was told they're grounds for the ECU. You'll want to make sure that they're clean and the surface you're bolting them to is clean as well. Any of the bolts that hold the two halves of the intake manifold together will work fine

 

[Dirgle]

This is a good point, and also makes having the chassis to engine grounds in just as good of condition, equally important.

 

[Van]

Brother! Those wires were connected to the battery positive pole of the starter when I tried to start the car last Saturday. It also caused the fuel pump relay to chatter and buzz. I disconnected those wires last week after another forum member suggested I had those wires connected wrongly. So now I'm not getting spark. Plug wires and plugs are new and within specs, the CPS and Igniter are newly rebuilt and in spec. I metered all the coils at 4 ohms (corrected). I note the TSRM has coils spec 2.4 - 3 ohms. So, they may be the cause for no spark. What do you think?
I'm guessing the ECU was damaged by sending voltage through the ground wires. That'll be the next item to sort out... tonight.
The engine turns over but won't start, due to lack of spark. Van

 

[IJ.]

Was just about to post that in the past people have connected them to the B+ post on the starter....

Not really sure what or how much damage is done by doing this but I suspect feeding 12v to the ECU's ground rail can't be a good thing, perhaps JJ can shed some light on this one.
(I'll pm him a link)

 

[jetjock]

As IJ said it's not a good thing. Does the MIL still come on with the key?

 

[Van]

As IJ said it's not a good thing. Does the MIL still come on with the key?

Hi JetJock,
Yes! Does my Mother In Law ever... LOL I assume you're referring to the so called check engine light? If so, I can't recall. I'll need to go out to the shop this evening to see. Thanks, JJ. Van

 

[Van]

As IJ said it's not a good thing. Does the MIL still come on with the key?

JetJock,
The check engine light doesn't come on with the key in ignition, at either on or start. :3d_frown: What could that mean? Van

 

[Dirgle]

Well it could mean that the bulb for the MIL indicator is burned out but based on the mishap with the ground it's likely something else. Check your fuses to be sure but if the MIL indicator doesn't light up it's a pretty good indication that your ECU is toast.

 

[jetjock]

^ What he said. Check the bulb, 15 amp EFI fuse, and Gauge fuse. Verify power at BATT and IGSW (key on). Along with the manifold ground those are the only things needed to turn the main relay on and supply power to +B...which should illuminate the MIL.

The dead MIL may have already been there (when did you last see it on?) and since the ECU doesn't have redundant grounding there's a chance, in theory at least, you may have gotten off lucky. What happened is in no way as bad as, say, connecting the battery cables backwards.

There may be some issues external to the ECU though. For example the speed sensor may no longer work. Check the things mentioned. If they pan out you're going to need another box...

 

[Van]

^ What he said. Check the bulb, 15 amp EFI fuse, and Gauge fuse. Verify power at BATT and IGSW (key on). Along with the manifold ground those are the only things needed to turn the main relay on and supply power to +B...which should illuminate the MIL.

The dead MIL may have already been there (when did you last see it on?) and since the ECU doesn't have redundant grounding there's a chance, in theory at least, you may have gotten off lucky. What happened is in no way as bad as, say, connecting the battery cables backwards.

There may be some issues external to the ECU though. For example the speed sensor may no longer work. Check the things mentioned. If they pan out you're going to need another box...

JetJock and members,

The last time I saw the check engine light on, was when I had the ground wires attached to the starter magnetic switch, along with the battery positive cable. Even then, all it did was glow.
Last night there was no light at all in any position of the ignition switch with the key in, or out. Not light.
In a related vein, last week when I had the ground wires connected wrongly, the main relay was getting so hot I couldn't stand to touch it for more than a second. At that same time, the check engine light was glowing and the fuel pump relay was chattering. Never once did I attempt to start the engine. I did spend several days trying to eliminate the cause through trial and error, by turning off the ignition removing a part, then turning on the ignition, only to hear the fuel pump relay chattering. Then I'd turn off the ignition and disconnect the battery positive and negative cables. I went through this process.
I hope this illuminates what I really did to the Supra...
Thanks. Van