HKS Turbo Timer IV Installation for 1993.5 – 1996 Supra Twin Turbo

Introduction to the Turbo Timer: Whether you have a turbocharged sports car, a turbo diesel truck or even a turbo wagon, the HKS Turbo Timer IV is a must. The HKS Turbo Timer IV is designed to extend turbocharger life in turbocharged vehicles by allowing the engine to idle for a pre-set amount of time after the ignition key has been turned "OFF " and removed from the key cylinder. This permits the engine oil to circulate through the turbocharger bearing housing which draws heat out of the bearings and impeller shaft to bring the temperature down to a safe level before the engine is shut down. If this "idle down" process is not practiced on a regular basis the hot engine oil will stop flowing along with the engine and sit on the turbo bearings causing long term damage. This process of cooking the bearings is known as "Coking". Coking is the number one cause of bearing failure in factory turbocharger failure.

Features of the HKS Turbo Timer IV:

  • 15 Preset times - 0 - 3 mins; 30 sec intervals
    • 3 - 9 mins; 1 min intervals
    • 9.59 and 9.99
  • Audible Alarm - An audible "Beep" can be activated or deactivated to "hear" the count down.
  • Safety Circuit - Connects to vehicles hand brake to disable Turbo Timer when brake is in the down position.
  • Add / Hour Meter - A resetable LED hour display to indicate engine running time. (Useful for timing oil changes and other routine maintenance.)

HKS Turbo Timer IV P/N# (MSRP)- HKS-4101-RA008 (~$100)

HKS Supra Wiring Harness P/N# (MSRP) - HKS-4103-RT004 (~$40)

*NOTE : The wiring harness is made for Model Year 1993-1996 ONLY. Model Year 1997+ is currently unavailable. A wiring diagram schematic is depicted below for those who would like to attempt at a custom job.

Equiptment Needed:

  • HKS Turbo Timer IV
  • HKS Turbo Timer IV Supra Wiring Harness
  • Short extension wire (~14 gauge)
  • 9 female "bullet" connectors (crimp type)
  • 9 male "bullet" connectors (crimp type)
  • 1 wire tap connector
  • Double faced tape
  • Velcro strips
  • Tools: Phillips screwdriver
  • Socket wrench
  • Multimeter or voltmeter
  • Exacto knife or similar sharp/fine knife
  • Electrical tape
  • Pliers
  • Wire cutters

Approximate Time to Complete: 30min-1 hour

Step 1: Installing the wiring harness

This step is pretty straightforward. Locate the 2 row, 10 mulit wire factory iginition harness under the dash almost direcly behind the iginition switch. There should be a black and blue harness nearby as well. Simply unplug the factory harness, and plug in the new HKS harness then the factory harnessThe wiring will T off so the Turbo Timer can be wired into the ignition system. No need to cut, tap wires, or anything. To ease installation you might want to undo the lower assembly of the dash (via two screws, though watch out for the A/C vent below).

Step 2: Installing the Ground wire and testing the Turbo Timer

At this point, plug in the mating "bullet" connector for the HKS Turbo Timer and make sure it is tightly secure. Attach the balck ground wire to bare solid chassis metal. There is an indiscriminate screw located behind the gas pedal which i used. At this point, turn on the car ignition and turn on the Turbo Timer. If it does not work, you do not have a proper ground, or the mating connector is not tightly fastened. To test the Timer's operation, make sure you'ce set the Timer's time to say 30SEC and simply turn the key to the OFF position. The car's electronical accessories should stay on as if you never turned it off and the Timer should start counting down. When the countdown is over, the car will power off automatically.

Step 3: Installing Parking Brake Safety Circuit

The safety circuit checks the hand brake and disables the Turbo Timer when the hand brake is disengaged. It also turbs the Turbo Timer off if the hand brake is turned on when the Timer is in use. Locate the Hand Brake wire by taking off the center console. This can be done easily by taking off the ashtray and yanking it out the fasteners attached (you might have to take off the shifter knob too and watch out for the ashtray light connector). You might also need to take off the sub assemby plastic housing around the parking brake via some screws. There will be a green/grey wire with a harness runing into the hand brake. With a multimeter, check for voltage. When it is engaged, it will read 0 Volts and when disengaged it should have about +12 volts. Connect the HKS grey ground wire to this line via the Electro Wire Tap or splice up the wire and crimp on the wire in a Y fashion. I used an extra wire to crimp on to ensure I had sufficient length to run behind the dash back over to the Turbo Timer unit. Now test the safety feature. When the Timer is counting down, if you disengage the hand brake, it should turn off immediately.

Step 4: Location and Operation

Location is a very sensitive matter, so I will leave that issue alone. I will note that for the life of me, I cannot the get the Turbo Timer to stick to the dash even when using heavy duty industrial strength double stick 3M tape, so instead I opted to extend the unit to the crevice between the driver seat and the center arm console hiding the wiring in the console. I use the default setting of 1 minute on my Turbo timer for nornal daily traffic. In high spirited runs, I increas this to around 2 minutes +. For quick errands, I decrease the time to 30 seconds or disable it entirely. YMMV

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MISC : Operation of Turbo Timer (courtesy of Geoff Seeley)

If you didn't receive any english instructions on the operation of the timer,
here is a brief synopsis of the functions:

The timer has two basic modes of operation, TIMER mode and ADD mode.


ON/OFF - Turn the timer on or off. Unless the timer was manually turned off, the timer will automatically turn ON (but not activate) with the ignition each time the vehicle is driven, and the time previously selected will also be retained in memory.

SELECT TIME - To select the idle time, press the UP or DOWN button to toggle to the desired time. The available selections are as follows:

0.00s - 0.30s - 1.00s - 1.30s - 2.00s - 2.30s - 3.00s -4.00s - 5.00s - 6.00s - 7.00s - 8.00s - 9.00s - 9.59s -9.99s

RESET TIME - To reset the time to 0.00s, press the UP and DOWN buttons simultaneously for at least 1 second.

ALTERNATING DISPLAY - To make the display alternate between the initial time selected and the time remaining in the countdown, press the UP and POWER buttons simultaneously for at least one second. (Be sure to press the UP button first) Press the sequence a second time to stop the alternating display.

RESET TURBO TIMER - To reset all functions and modes (including the cumulative hours recorded in the ADD mode), press the ALARM and POWER buttons simultaneously. (Be sure to press the ALARM button first)

ADD MODE (Engine Hour Meter)

ON/OFF - When the timer is in TIMER mode, press the ALARM and DOWN buttons simultaneously for at least one second. The cumulative number of hours the engine has running should appear on the display. To return to TIMER mode, press the sequence a second time. If the ignition key is turned OFF, the display will revert to the TIMER display automatically. The timer will revert back to ADD mode the next time the car is started. (ie. whichever mode the timer is in, TIMER or ADD, will be remembered and restored)

FLASHING DISPLAY - The timer can be programmed to flash ON and OFF while in ADD mode to indicate that the timer is recording the number of hours of engine operations. To turn the flashing display on or off, press the UP and POWER buttons simultaneously for at least one second. (Be sure to press the UP button first)

RESET TIME - To reset the cumulative hours recorded in the ADD mode, press the UP and DOWN buttons simultaneously for at least one second.

RESET TURBO TIMER - To reset all functions and modes (including the cumulative hours recorded in the ADD mode), press the ALARM and POWER buttons simultaneously. (Be sure to press the ALARM button first)


Comments/suggestions? Email me   (Brian B.)


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