Skyline Diagnostics

ECU diagnostics

The ECU is found in the passenger footwell, behind the plastic kickplate to the left of your feet when sitting. Usually you have to remove the computer from the mounts in the footwell, as the LED(s) you need to see is pointing away from you.

Switch on the ignition, but don't start. The LED on the ECU will be glowing.

Turn the selector screw clockwise all the way (gently!)

 

There are three different types of factory ECU available in Skylines.

One type has two LEDs and five modes

The other type has one LED and two modes

The last type has no LEDs, the output is done with the engine check light in the instrument cluster. Acts as a single LED ECU.

 

 

For two LED EDU's: the LED will flash once, pause, flash twice, pause... all the way up to five. This is the diagnostic mode. Mode 1 = one flash, mode 5 = five flashes. When you reach the right mode, turn the screw back counter-clockwise. Mode 3 is what most people use.

For one LED ECU's: wait a couple of seconds, and turn the screw back counter-clockwise, the ECU is now in mode 2.

Note - the engine check light on the dash will mirror the LED on the computer.

The LED will flash out a code (or series of codes if there is more than one fault) More recent ECU's have two LED's (red = first digit, green = second digit, eg red 2x flash, green 1x flash = code 21) The ECU's on most R32's have one LED, long flash = first digit, short flash = second digit, eg long, long, short = code 21.

Codes:

11 Crankshaft position sensor
12 MAF sensor circuit
13 Coolent temperature circuit
14 Vehicle speed sensor circuit
21 Ignition circuit
31 ECU (ouch!)
34 Knock sensor
43 Throttle position circuit
45 Injector leak
51 Ignition circuit
54 Auto signal to ECU
55 All OK

Turn the ignition off to put the ECU back to normal.

There is also a O2 sensor test in real time available - do the above to get the ECU into mode 2 (single LED ECU) or mode 1 (2 LED ECU's) Start the engine. Warm the engine, and then run under no load at 2000 rpm for the test.

Single LEDs: on = lean, off = rich

Dual LED's: green LED on = lean, green LED off = rich

Go by the trend shown, eg mostly on = lean, mostly off = rich. The LED should be flashing between 5-10 times per 10 seconds under normal conditions.

HICAS Diagnostics

What is HICAS? And do I have it?

Good question. HICAS is Nissan’s version of four wheel steering. It is an acronym for High Capacity Actively Controlled Suspension. Unlike other Japanese car manufacturers 4WS (eg Honda’s system) HICAS never exceeds +/- 1°. It is designed for high speed response rather than parking manoeuvres.

The system is electro-hydraulic - the ECU in the boot directs a hydraulic actuator at the rear axle to steer the rear wheels using the rearmost suspension links. The result is usually no more than 0.4° of movement. HICAS gives a touch of counter steer before settling with the rear wheel pointing the same way as the front. (Maybe this explains why my Skyline feels so loose on high-speed gravel...) This results in sharp turn-in, and enhanced stability at medium to high speeds.

Anyway, have a crawl under the rear of your Skyline and have a look. After following the description in the paragraph above and if it looks like the picture below, you have HICAS. NB: The R33 series has an electronic actuator, it looks slightly different.

Procedure:

  1. Switch ingition off, transmission in neutral or auto in Park.
  2. Start engine
  3. Very quickly (with a couple of seconds), turn the steering wheel left and right about 20 degrees from centre five times, and then pump the brakes five times, then press the brake pedal once more - this will enter diagnostic mode.
  4. Drive forwards or backwards about 5 metres at a speed less than 10k/ph, this will enter full diagnostic mode.
  5. The HICAS light in the instrument cluster will be flashing quickly (for normal) or will flash a code indicating any problems. Long flash = first digit, short flash = second digit. Diagnostics will return to normal after five minutes, or any speed over 10k/ph, or ingnition is turned off.

HICAS 1990-1993 (seems OK for '89 as well)
1 HICAS solenoid right hand
2 HICAS solenoid left hand
3 Cut off valve
4 Power steering solinoid
5 Vehicle speed sensor
6 Steering angle sensor
7 Neutral position sensor
8 (Auto) Parking brake sensor, (Manual) Clutch sensor
9 (Auto) Inhibitor switch, (Manual) Neutral sensor

 

HICAS 1994-1999
11 HICAS control unit
12 HICAS motor power supply not present
13 HICAS motor output not present
21 Vehicle speed sensor not present
22 Steering angle sensor not present
23 Steering angle sensor neutral or not present
24 Rear main sensor input not present
25 Rear sub sensor input not present
31 Parking brake sensor input not present
32

(Auto) Inhibititor switch input not present

(Manual) Neutral switch input not present
32 Engine speed signal not present

Auto Transmission Diagnostics

Enter the auto transmission diagnostics mode

  1. Have the car at normal temperature in Park with the overdrive on
  2. Start the engine ­ the power light will go out after 2 seconds
  3. Turn the ignition off
  4. Move the selector to Drive (you may have to use the push button release)
  5. Overdrive off Wait 2 seconds, and turn the ignition on
  6. Wait 2 seconds and move the selector to 2
  7. Overdrive on
  8. Move the selector to 1
  9. Overdrive Off
  10. Press the accelerator fully and release
  11. Read the auto transmission diagnostics codes.

All codes are flashed with the Power Light on the dashboard (R32) and on the auto mode selection button on the R33's.

The sequence starts with one long flash.

If everything is OK, this will be followed by ten short flashes. Errors are indicated by a long flash in the sequence of short flashes.