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addisonblc, if you are still on the forums thank you for this writeup!
Having read through the last page I wanted to ask to confirm: for the HKS (or any company's TT) could I use a JZA80 Supra harness or would I ideally want to find a Soarer timer harness? Or does neither matter since the USA SC driver's side fuse area is different from both of those models?
the ebrake wire is a security function. the turbo timer only works when that wire is grounded, so when the parking brake is up and that wire is connected right, its grounded and it allows the turbo timer to keep the car on as long as the handbrake is up/on. when the handbrake goes down the turbo timer will shut off the engine no matter what, or wont keep it running extra after shut down like you want it to.
as soon as someone goes to put down the parking break (To move or steal your car), then the ground is broken and the turbo timer just shuts the car off.
IF you do not connect this wire the turbo timer will not turn on as in your car will shut down like factory. if you don't care about the safety feature then you can just ground this wire anywhere and the turbo time will work, but then someone can just drive off with your car. you could also do it with the foot brake if you have an automatic or just willing to take a gamble a car thief will press the brakes at some point vs letting down the handbrake. I would connect it to the handbrake like normal, or just as a test ground the wire temporarily to make it work but do realize the safety feature is bypassed that way.
Bumping to add some research I've done to make my own DIY replacement for the discontinued HKS TT-5 turbo timer harness for JZZ30 Soarers (and by extension SC's). I know that most will say that there is no need to go to such lengths when the wires can be tapped but I prefer to create plug and play patch harnesses whenever I can so as to not mess with original wiring especially when it's very tightly confined and not easy to get to as in this case.
To start, other than the great info in this thread which has essential visual references to the correct wires that need to be tapped I also researched these other threads which go into some of the OBD1, OBD2 and JDM Soarer wire color differences even though the pin locations do not change (or shouldn't but checking wiring for 1998-00 SC300's or Soarers for consistency may be a good idea):
To my knowledge HKS only ever made one version of their TT-5 harness for ALL 1991-2000 Toyota Soarers.
Here in HKS's own up-to-date turbo timer harness chart you can see that the TT-5 model isn't even listed any longer: https://www.hks-power.co.jp/en/produ...ch/product/544
So here is how to make one.
First, here is what an HKS TT-5 harness looks like. Note that you if you look closely the connectors used are different from any other connectors used on any of their other harnesses.
There are actually 11 pin locations on these female and male connectors. Seven very large spade/terminal slots and four small spade/terminal slots.
I managed to track down the part numbers of the original Toyota connectors that the SC's ignition system uses. They are:
90980-10873 male housing w/female receptacle connectors (lower and most accessible with the release tab on top)
90980-10872 female housing w/male spade connectors (upper and least accessible)
They took a while to get as they are not commonly stocked. These should cost between $18-$30 as a set depending on where you order them from.
Edit/Note: I was able to find at least one vehicle for which these connectors cross-reference and that is to a 1996 Toyota Land Cruiser (FJ80). If you look into this thread below you will see that they are the same connectors that are also used by the 1992-2000 SC300/400 and 1991-2000 Toyota Soarer.
The terminal repair wires for these connectors are as follows:
90980-10873 HOUSING, CONNECTOR F x1
90980-10872 HOUSING, CONNECTOR M x1
82998-12370 TERMINAL, REPAIR W/W x7 (but only six are used for the SC)
82998-12330 TERMINAL, REPAIR W/W x4
82998-12380 TERMINAL, REPAIR W/W x7 (but only six are used for the SC)
82998-12340 TERMINAL, REPAIR W/W x4
I would recommend only buying the terminal repair wires needed to complete this harness after cannibalizing another HKS turbo timer harness for whatever wiring will fit as detailed below:
Next I bought myself an HKS TT-3 harness for MKIII Supras because it looked like it was the most similar to these connectors such that I would have a chance of re-using some its existing wiring/terminals. In fact this worked out very well even though it does not have all the wiring needed to complete a JZZ30 or SC application.
Next, some investigative work was needed to determine what all of those pins on the factory SC connectors in the car are supposed to do.
I started with some deep searching of the SC300/400 wiring TSRM and found that these connectors are labeled "I15" and indeed they are 11 pin types.
Here is the 90980-10873 connector with the terminal ends *facing you*:
Note that Pin 5 of this connector or its matching counterpart is not used for SC300's.
For those who want to see the wiring diagram research, here are some screenshots:
There are a couple of others that may detail a couple of pins but here is a breakdown that I have come up with:
From SC300/400 TSRM I15 connector:
Pin 1 — “ST1” B-W (Black-White? Blue-White?) to 1J-6 “7.5A ST” Fuse
Pin 2 — “IG1” B-Y (Blue-Yellow? Black-Yellow?) to 1J-5 “7.5A ENGINE” Fuse
Pin 3 — “ACC” P-L (Pink-L?) to 1J-8 “7.5A Radio No.2” to Integration Relay I16-11 “ACC”
Pin 4 — “AM1” White wire to 1J-7 “40A IGSW” Fuse
Pin 5 — “X” ***NOT USED***
Pin 6 — “IG2” B-O (Brown-Orange? Blue-Orange? Black-Orange?) to 1J-3 and(?) Alternator?
Pin 7 — “Key Interlock Solenoid IGNITION SW” W-B (White-Black? White-Blue?) (NOT USED BY M/T MODELS)
Pin 8 — “Key Interlock Solenoid IGNITION SW” V (wire color? Violet?) to IG1-12 Shift Lock Control (NOT USED BY M/T MODELS)
Pin 9 — W-B (White-with-black-stripe) “Unlock Warning SW”
Pin 10 — Y (Yellow) “Unlock Warning SW”? to 1I-15 “KEY”
Pin 11 — “AM2” White-Red wire to IE1-16 to Fuse Block F9 Pin 13 (30A Injector Fuse?)
Wiring Guide for the 1992 SC300 wire colors translated into connector pins:
Constant 12V ——— white+white/red wire on SC (I15, Pin 11)————> to red wire on turbo timer
Accessory Power — pink/blue wire on SC (I15, Pin 3) ———————> to blue wire on turbo timer
SC300 Ignition #1 — black/orange wire on SC (I15, Pin 6) —————> to green wire on turbo timer
SC E-Brake ————black wire under arm rest ——————————> splice and connect to HKS Ground
Below is a photo of the wiring from the female 10873 connector in my 1993 SC300 original 5-speed M/T. Note that pins 7 and 8 are not populated since only the automatic cars have “key interlock solenoid” wiring in those areas.
....
Using all of that information it is possible to use the two SC ignition connectors listed above, cannibalize an HKS TT-3 harness and *mostly* plug and play to each correct pin and then order the remaining terminal ends needed to complete the final small wiring connections needed at Pin 9 and Pin 10. Pins 7 and 8 pertain to ignition interlock circuits only used with automatic SC's so if you have an automatic you will need to complete those as well. My original 5-speed M/T body harness had no wires going to/from Pins 7 and 8 since it was never equipped with that circuit.
Also I noticed that the stock SC harness connectors have some VERY thick wires in the larger spade areas. The HKS harness has slightly smaller gauge wire in these areas. I would assume the same would be the case for their other turbo timer harness applications that are made exactly for the model you're using the pre-made harness wiring for but perhaps to be ultra-safe one could also order all of the SC connector terminal ends in the thick gauge and just build the harness that way not by cannibalizing a fully built turbo timer harness from another model but just with HKS's universal turbo timer harness splice-ready wiring.
However a big reason I opted to cannibalize an HKS TT-3 harness for some of its pre-made wiring is that I figured this would actually be much cheaper than buying each and every wire for both connector sides from Toyota rather than only the few that would not be available to pilfer from the TT-3 harness. I turned out to be correct about that. I got my TT-3 harness (to be used for parts only) for $22 shipped from Driftmotion.
Anyway, when nearly completed (I am still missing the small terminal wire connections in this shot), the nearly finished DIY patch harness should look like this:
^^ The advantage over letting the engine idle for two minutes is that I don't have to always religiously sit in the car while it idles for those two minutes (or whatever idle time is desired). The turbo timer does exactly the same thing (whatever time you set it for) but relieves the driver from having to sit there.
Some of the time it's no problem to wait while the engine idles for a bit to allow the oil to circulate through the turbo(s) to allow for cooling. In my case both turbo housings are also water cooled which makes for less of a potential issue. Still there are some times and situations where time is of the essence and it would be better to just allow a specialized device with a timer to do this work for me and shut the engine off automatically once it's done.
Since my SC is not a weekend warrior but a daily driver it just makes things more convenient in my opinion. Allowing the oil pressure to normalize on a cold startup before driving off cannot be rushed but any cooldown considerations can be automated if the car hasn't already been driven moderately for a couple of minutes before parking.
It's completely personal preference and yes, the same exact thing can be done just by driving calmly (ie: not boosting or not boosting much at all) for a couple of minutes or by sitting with the car while it idles for a couple of minutes. Is it really worth it to have a semi-pricey little ignition-off timer do that for you? That's up to you and how disciplined you are or how you even use the turbo car.
I won't use the turbo timer all the time but I do want it there for the times I really want to use it. Maybe if this were a weekend-only or event-only car I wouldn't bother installing one. As someone on SupraForums said, turbo timers are "cheap insurance" and really cannot hurt if the objective is to prolong the life of the turbo(s).
I would reason that the Japanese market came up with several of these ignition timers since the 1980's because over there a lot of common cars that aren't even specialty sports cars have been turbocharged for a very long time. In the USA it's a relatively new thing to have a large number of "normal" everyday cars that are turbocharged. It could be looked at as a gimmick or it could be looked at as a solution to allow for both turbo preservation and driver/owner convenience.
Another thing is that the turbos I have are 90's era designs and the Toyota owner's manual does state that some cool-down under hard driving conditions is recommended. Modern cars with factory turbos made in the last few years may have no such recommendations in their owner's manuals but I'm sure at least the high performance type models which are expected to be driven hard probably do still recommend some idling to let the turbo(s) cool down.
Either way it comes down to one's personal preference. There's no harm in installing one and there's also no need for one if you always, always make sure you let your turbocharger cool down before shutting the engine off.
Some of the time for one reason or another when you have to be somewhere and time is of the essence a turbo timer can be a nice thing to have. Again, if one never uses their turbo car as a daily driver perhaps a turbo timer never needs to be a consideration at all. It's just a simple means of being sure that a cool down period always happens no matter what.
This patch harness replica I made just makes the installation or desired removal a lot cleaner in an SC since HKS no longer makes it for the Z30 Soarer / SC. Any of their turbo timer models will plug into it.
07-22-14, 01:59 AM
