Project Thread Supercharged Supra

[scotturnot]

John, I am using a factory 97 Sc400 harness. Mitch got me the pin outs and changes. I needed to add a few wires to it but the process was fairly easy. In a couple instances I actully used wires in the harness that we no longer used. I will look up some of what Mitch sent me if it will help. Keep in mind, mine has yet to run.

 

[stevechumo]

.. If I purchase an early SC400 harness, it’ll already have the correct V8 layout, but the injectors will e setup for four groups of two in batch fire, plus it’ll be setup for 2 distributors, not 8 COP’s. Really the only things it’ll have going for it, is its layout for a V8 engine, its ECU connectors will fit my AEM, and I think it'll be setup to penetrate the firewall in the same place as in the Supra....

I'm not an expert in wiring, but I'd have idea. I'd use the SC4 harness, wire 8 injectors & distributors separately and connect them directly to the AEM ECU connectors. Basically it's to bypass the stock injectors & distributor wires.

 

[cribbj]

Thanks Scott, after looking at the wiring diagrams, the '97 harness at least offers all 8 injectors wired for sequential firing, not batch fire as the earlier models did. Still only 2 distributors, so I assume you had to find at least 6 more wires for your COP's.

If you've the time I'd really appreciate some pics of that harness right where it comes through the firewall into the engine bay, and where it (presumably) splits to feed both banks of the engine? And as you mentioned, whatever Mitch sent would be helpful. Although I've been fooling around with these 1UZ's for a number of years now, I've never popped the hood of an SC400 to see what the wiring harness looks like, nor do I know anyone closeby who owns one.

Steve thanks for your idea, but since I'll be running 8 COP's, in addition to the 8 individual injectors, I'd need to pull at least 16 new wires to bypass the OEM harness. It could be done, but I'm trying to keep it all within the OEM harness, if possible so it looks OK when it passes through the firewall.

Fortunately, since I'm using COP's with integral ignitors, the heavy current carrying conductors will already be on the engine, and all that's needed for the coils will be fairly small conductors from the ECU to trigger the COP's.

 

[spdrcr771]

Thanks Scott, after looking at the wiring diagrams, the '97 harness at least offers all 8 injectors wired for sequential firing, not batch fire as the earlier models did. Still only 2 distributors, so I assume you had to find at least 6 more wires for your COP's.

If you've the time I'd really appreciate some pics of that harness right where it comes through the firewall into the engine bay, and where it (presumably) splits to feed both banks of the engine? And as you mentioned, whatever Mitch sent would be helpful. Although I've been fooling around with these 1UZ's for a number of years now, I've never popped the hood of an SC400 to see what the wiring harness looks like, nor do I know anyone closeby who owns one.

Steve thanks for your idea, but since I'll be running 8 COP's, in addition to the 8 individual injectors, I'd need to pull at least 16 new wires to bypass the OEM harness. It could be done, but I'm trying to keep it all within the OEM harness, if possible so it looks OK when it passes through the firewall.

Fortunately, since I'm using COP's with integral ignitors, the heavy current carrying conductors will already be on the engine, and all that's needed for the coils will be fairly small conductors from the ECU to trigger the COP's.

I dont know it this will help you or not but, im pulling my 98 vvti 400 engine out tomorrow, i could take pics of the harness while im pulling it & after its sitting on the engine stand or ground. I gotta take pis of the intake manifold anyway for scott. Let me know if there is any certain area or plugs that you want pics of, to see if they might match you AEM

 

[cribbj]

I dont know it this will help you or not but, im pulling my 98 vvti 400 engine out tomorrow, i could take pics of the harness while im pulling it & after its sitting on the engine stand or ground. I gotta take pis of the intake manifold anyway for scott. Let me know if there is any certain area or plugs that you want pics of, to see if they might match you AEM

That would be great, thanks! I'm interested in the following:

1. What do the ECU plugs look like (I think I know already, but could be pleasantly surprised)

2. Where does the harness go through the firewall? Passenger (right side) of the firewall like on previous years?

3. What does the fitting look like where the harness goes through the firewall? Hopefully the same as the Supras - sort of an oval flange?

4. What does the harness look like where it leaves the firewall and comes onto the back of the engine?

Thanks again.

 

[scotturnot]

Thanks Scott, after looking at the wiring diagrams, the '97 harness at least offers all 8 injectors wired for sequential firing, not batch fire as the earlier models did. Still only 2 distributors, so I assume you had to find at least 6 more wires for your COP's.

If you've the time I'd really appreciate some pics of that harness right where it comes through the firewall into the engine bay, and where it (presumably) splits to feed both banks of the engine? And as you mentioned, whatever Mitch sent would be helpful. Although I've been fooling around with these 1UZ's for a number of years now, I've never popped the hood of an SC400 to see what the wiring harness looks like, nor do I know anyone closeby who owns one.

John, I will try and put some stuff together this weekend.

 

[spdrcr771]

This is what pics ive taken so far.

 

[cribbj]

Beautiful, thanks a bunch for the very clear pics. Unfortunately for me, it's as I thought with the ECU connectors - they changed from '97 to '98, and the '98 connectors are completely different, and aren't PnP with the AEM.

Might still be an opportunity for an enterprising soul to make an adapter or jumper harness, though.

 

[cribbj]

I could've sworn I posted this the other day, but maybe I'm losing my mind faster than I thought......

Anyone recognise this plug on my alternator? I'm looking for the number of the matching connector. I've checked the wiring harness book, and asked several people in Toyota parts, but they don't recognise it. Hmmm.

Much appreciated if anyone has a P/N for the mating connector:

 

[stevechumo]

I just removed the alternator and sent it out to David 2 days ago. And I didn't know you're looking for the P/N. But my memory says that the plug on your alternater doesn't look like mine. Mine has a square/rectangle shape. It seems to me your plug doesn't look OEM, and it could be why it doesn't match with your harness.

 

[cribbj]

Thanks Steve, from the little I know about Toyota/Denso alternators, their plugs are usually round or oval (at least on the Supras), but not this kind of oval....

 

[MitchP]

Looks to me that that alternator is dented as that plug should be round. I have had to source connectors for that alternator before but don't remember the application. Think maybe rx7 or Honda. Will pool around and see what I can figure out for you.

Also, the connectors for the later model ecu's are obtainable and I have made patch harnesses for people in the past so if you need one, let me know. I have straight through patch harness with those connectors at my shop right now. It is the same connect that's on my two factory 1GZ ecu's.

 

[Zuffen]

My alternator has the same plug.

I found one at a wreckers (junk yard) attached to an old Toyota alternator in a giant heap of alternators.

I think it was off a Corolla.

 

[cribbj]

Thanks Mitch & Rod, guess I need to troll the junkyards for a connector when I get home.

Mitch that's good news on the ECU connectors. So do you have the "opposite" connectors that will mate to the late model SC harness?

One option might be to start with the late model SC harness, then use a patch harness to plug into the AEM. I like the idea that it's already setup for the 8 COP's and injectors.

Still haven't eliminated the possibility of using a 2JZ harness, however, and it has the advantage of plugging right into the AEM, without needing a patch harness.

Just weighing options. Wherever electricity and signals are concerned the fewer the connections, the better.

 

[stevechumo]

Here's a picture of my alternator that fits directly on stock harness. My car is a 95 SC400. I couldn't find the part number because this is a rebuilt one.

 

[cribbj]

Thanks Steve, yes that connector looks more like it. I might have better luck changing the alternator than finding a connector for it!

 

[cribbj]

OK Front Dampner pulleys: anyone know if there's any big differences between the 1UZ and 2UZ dampner?

'Cause I get better prices on Toyota parts than Lexus, I'm getting ready to buy a new 2UZ dampner in lieu of the 1UZ, and want to be sure Toyota didn't change something important.

 

[Peewee]

John,

As pointed out above, that alternator has been dropped and landed on the plug corner.
That plug should be perfectly round.

Most pre1990 Toyota's (at least the larger ones) will run that plug.

My MX73 Cressida and the MA61 Supra's do.
Pretty sure my 1990 LS400 does as well.

 

[cribbj]

Thanks Peewee; I've got a junk alternator here also, and it has the same internal connections as the weird one, but it has a true round housing. So I guess as everyone says, it probably got dropped.

It's headed for the junk pile, and I'll get a new high output one with the square/oval connector. Those seem to be the standard on the later models with the higher outputs, and I do want a good weatherproof connection on this puppy.

 

[Zuffen]

That alternator hasn't been dropped.

The 3 spade terminals are all in a nice row.

The round plug has 3 terminals 2 are parallel with the 3rd at right angles to the others.