99' GS400 Wiring

[Spinnetti]

Got more or less the full engine, trans, brakes, ESC, Cluster, working Key Steering Column and wiring harness from a wrecked 99' GS 400 (VVT/5 speed) and put in my 91 LS body shell. I got all the mechanical bits sorted, and the full engine/trans harness is intact and in place. I'm trying to get it wired to run now by connecting the wires from the fuse boxes and ecu to the body harness (using only the GS parts). This is a race car, so I got rid of everything I could find for seats, HVAC etc. I have what I think I need plugged in except the fuel pump. When I turn the key the cluster lights up, but no love when I go for start (no relay or crank). Does the fuel pump have to fire before the ecu will let the starter relay fire and the engine crank? I've got some work to do yet to convert the fuel return based system converted to returnless, so don't have it hooked up yet.

Any advice appreciated... I'm not nearly as good with electric as I am mechanical

 

[George_R]

starter relay circuit is broken by inhibitor switch located on transmission (so you can't start in D or R for example). Check it, as well as your fuse/relay box for powering the relay

As for fuel pump, it only works when ECU sees cranking, either from CAS or from starter signal (whatever appears first). It's controlled by another small "computer" but of course it is not needed for a race car

 

[Spinnetti]

starter relay circuit is broken by inhibitor switch located on transmission (so you can't start in D or R for example). Check it, as well as your fuse/relay box for powering the relay

As for fuel pump, it only works when ECU sees cranking, either from CAS or from starter signal (whatever appears first). It's controlled by another small "computer" but of course it is not needed for a race car

Thanks! So sounds like should crank regardless if the inhibitor isn't open. If the switch is on the shifter rather than the trans I probably removed it, but if on the trans, all the trans wiring is intact.

I've tried to do this with just the standard repair manual, but its too much for me.. Any online source for the electrical manual? That way I can find out what each plug does, where it is and chase each wire. This is USA 99 GS400. I've got LS, so maybe most of that will cross over (?)

 

[Spinnetti]

PS - you did a cool project! (risky move with the Audi tho!). So looks like you have basically the same engine project I do - VVTI motor in a different car. Does it need anything for the rear O2's? I thought those could just be left off and it wouldn't affect tuning...

 

[George_R]

The switch is located on the trans
Keep in mind that body loom is heavily involved when it comes to power source, gear position signals and some other things.

The best online source for toyota diagrams is techinfo.toyota.com . 2-day subscription costs you a beer, but then you get every bit of info and it's official. So you don't need to rely on someone's hand drawn things.

LS400 and GS400 are really very close to each other, even to the point GS400 ECU would run LS400 engine without any problem. Sub o2 sensors - you may skip them for now. Later on you would need electronic device that simulates sub o2 sensor signal based on the data from primary sensors. But the engine would be almost ok even without one.

Thanks for your opinion on my project ) Mine is a bit different in that I don't need ABS, TRC etc etc , and I use JDM ECU for some reason.

 

[Spinnetti]

The switch is located on the trans
Keep in mind that body loom is heavily involved when it comes to power source, gear position signals and some other things.

The best online source for toyota diagrams is techinfo.toyota.com . 2-day subscription costs you a beer, but then you get every bit of info and it's official. So you don't need to rely on someone's hand drawn things.

LS400 and GS400 are really very close to each other, even to the point GS400 ECU would run LS400 engine without any problem. Sub o2 sensors - you may skip them for now. Later on you would need electronic device that simulates sub o2 sensor signal based on the data from primary sensors. But the engine would be almost ok even without one.

Thanks for your opinion on my project ) Mine is a bit different in that I don't need ABS, TRC etc etc , and I use JDM ECU for some reason.

Thanks for the tips.. I ordered up a electrical manual earlier off ebay, but I'll check that site out. Since my engine harness is intact, it was really what all the body plugs look like and where they go so I can figure out what to chop. LS is different enough that I didn't have confidence. Cost for manual wasn't bad.. Had I been thinking, I'd have just logged into Toyota's repair system (TIS); I work at HQ after all, but was too impatient, and didn't have my work laptop at home.

 

[Spinnetti]

Just checked the site - funny.. didn't realize it was the same site I have at work. I'll download the bits I need tomorrow. Won't hurt to have a spare manual I suppose.

 

[George_R]

To me, body loom is over complicated, and besides it's way too rare and thus expensive.
So I never use one.

Instead I look at the diagrams and run the wires I need one by one. Then install new "universal application" relays and fuse boxes (Herth & Buss, Hella).

When I'm about to install some engine into next customer's car, I usually make conversion loom at home. The loom would have the 3 ECU plugs, fuses, relays. And a bunch of labeled wires that I will solder to engine loom when working with the car. I found this approach to be easier and more fail safe as the most important part of the loom is made at home in relaxed atmosphere

 

[Spinnetti]

To me, body loom is over complicated, and besides it's way too rare and thus expensive.
So I never use one.

Instead I look at the diagrams and run the wires I need one by one. Then install new "universal application" relays and fuse boxes (Herth & Buss, Hella).

When I'm about to install some engine into next customer's car, I usually make conversion loom at home. The loom would have the 3 ECU plugs, fuses, relays. And a bunch of labeled wires that I will solder to engine loom when working with the car. I found this approach to be easier and more fail safe as the most important part of the loom is made at home in relaxed atmosphere

That's a smart way to do it, but I only do a full swap like this about once a decade (or less) so it just takes me too long as I don't have enough practice. The last one I did was one of the first 20V 4AGE's in a MKI MR2 (in the US), and I didn't love doing it then either. I'd gladly pay somebody to wire the body harness, but nobody around here to do it. I'd like to keep the ESC too for those snowy race days (have had a few) which adds some complication. I didn't have any problem thinning out the LS harness, but with just the big bundle of wires from the GS, its been a lot harder.

 

[George_R]

LSD is much more important for snow/ice racing! Almost as important as locating some shallow lake and keeping all the windows open ;-)

When stripping the original body loom, I would recommend that you start with the power source. Make sure you have 12v at BATT, +BM at ECU. Then make sure you have 12v at IGSW @ ECU, and at power supply pins at injectors and coils, when the ignition is on.

After that you may move on to the 2 important relay controlled by ECU pins FC and MREL, and that would be a good start already

Having sorted the above, you will only have to check your immobilizer system and starter relay

 

[Spinnetti]

LSD is much more important for snow/ice racing! Almost as important as locating some shallow lake and keeping all the windows open ;-)

When stripping the original body loom, I would recommend that you start with the power source. Make sure you have 12v at BATT, +BM at ECU. Then make sure you have 12v at IGSW @ ECU, and at power supply pins at injectors and coils, when the ignition is on.

After that you may move on to the 2 important relay controlled by ECU pins FC and MREL, and that would be a good start already

Having sorted the above, you will only have to check your immobilizer system and starter relay

Sweet, that helps narrow it. I logged onto TIS at work and looked up the wiring today which will help. As to the LSD, I modified the subframe to take the diff carrier from a 99 SC300 Auto, which has 4.26 gears, then put a new in box Supra TT Torsen 2 in it that I got from the Supra forums... with this engine/trans/diff combo its going to be fantastic. The old motor was good, but this will be as good as this combo gets I think (within rules/budget). The 5 speed trans has much better ratios, about like a manual has.

 

[George_R]

I would recommend getting modified valvebody or lower diff ratio say 3.7
Mine is not comfortable with 4.1 diff (though it's nice off the line) because the trans has to shift too often and each shift lasts forever.

 

[Spinnetti]

I would recommend getting modified valvebody or lower diff ratio say 3.7
Mine is not comfortable with 4.1 diff (though it's nice off the line) because the trans has to shift too often and each shift lasts forever.

Quicker shifts might be nice, but at the limit a smooth shift upsets the car balance less than an abrupt shift. The 4.27 gearing has worked great - I'm very happy with it. Its the 340e trans that had way too long gears so we were never in the power band. The 600 series trans fixes that... I've got the mechanical package just where I want it; Just need to get it to run again!

Thanks for all the tips.

 

[exhaustgases]

What kind of race do you do with a 4 door car? Also how well do all those parts fit?
Is it all pretty plug and play so to say, no cutting drilling etc? And a question if its just an off road that is race track only type of deal, why not go to a dedicated engine and transmission controller? It would probably be way less trouble than dealing with the fussiness of the LS ecu's.

 

[Spinnetti]

What kind of race do you do with a 4 door car? Also how well do all those parts fit?
Is it all pretty plug and play so to say, no cutting drilling etc? And a question if its just an off road that is race track only type of deal, why not go to a dedicated engine and transmission controller? It would probably be way less trouble than dealing with the fussiness of the LS ecu's.

This is the "24hrs of Lemons" Its all got to be done for essentially no money.... So, I cut up stock stuff. the 99SC rear diff carrier didn't fit the car, so fabricated and tig welded on new diff mounts, and swapped the rear cover with the one from the early car and Viola. Can't use aftermarket ecu as it violates both the spirit and letter of the rules... will have to slog through the stock stuff. Still don't have it running. Dash lights up, but no start. Next will be to mod the fuel pump (to make it returnless to match the later wiring and multi-speed fuel pump controller). None of this is plug and play. Nothing mounted straight up. Had to mix and match parts from the 91LS and 99GS (e.g. GS front half of the drive shaft, and back half from the LS) plus a fair bit of fab work - but it was all just a junked spare GS and labor. Mechanical package is done, just struggling with the wiring still and its been sitting a while, then a cross country move.... Just want to find somebody to get the basics to work so get motivated again

 

[Spinnetti]

Just a quick update.

I did eventually sort it all out, and we are right up front with the fastest cars on track. Its super stable and easy to drive.

We ran without power steering, but with 2.5hr stints some of the drivers got tired and it was hard to steer quickly when things go sideways so I put in Prius EPS and lengthened the steering shaft for a short reach. Works really great. Only part I never figured out very well is that it runs richer than it should, so I just run an air bleed after the MAF to lean it back out a little. ABS doesn't seem to work either but not sure how to test it (I suspect I wired up one of the rear sensors backwards but not sure if that makes any difference since they are just pulse generators?)

Need to freshen up the trans for this year and will shim the valves & up the line pressure for faster shifting.

 

[Lextreme]

Thanks for the update, Spinnetti. Sounds like you put a lot of work into it. Got pics of anything?

 

[Spinnetti]

I like watching other people's race videos of us blowing by them so fast it looks like they are going backwards. You can watch just the first few seconds of these clips to see us go by

- Passing the "Lustang" (1UZFE powered Mustang)

https://youtu.be/y6bjdualE5g?t=2744
https://youtu.be/YuMKryg0AsU?t=1169