» You are NOT logged in!
LOGIN or REGISTER!

If you haven't registered yet, please do so by clicking  here. The benefits of registering include an endless wealth of  technical information, access to our forums, and best of all, this god awful big red eye sore of a notice will disappear!!
» Z32 ECU Diagnostics & Troubleshooting Proceedure
ECU Diagnostics
Article Date: 04-12-04
Author: Twisted Six
Mod Class: Z32 All Models
Mod Type: Diagnostics
Article Origin: Zmods.org
Difficulty Level: 1 (Scale of 1 to 10. 1 being extremely easy, 10 being extremely difficult.)
Estimated Time to Complete: Less than an hour

Tools Required:
10MM Socket with 6" extension
Small Flat Screwdriver

To test for ECU codes, you need to gain access to the ECU itself. It's located under the false floor in the passenger side floorboard. Follow the steps below to gain access to the ECU.

1) Remove the passenger floor mat.

2) Peel the carpet back, it's only attached with Velcro.

3) Remove the wooden false floor, it's held in place with 4x 10mm bolts.

4) On the side of the ECU there's potentiometer. On a Z with an automatic transmission, you have to take the transmission control module loose to gain easy access to the potentiometer.

5) Turn the ignition switch on, but do not start the engine.

6) Turn potentiometer (diagnostic mode selector) fully clockwise. Wait at 2-3 seconds, then turn potentiometer fully counter clock-wise. The ECU is now in Diagnostics MODE II Diagnostics.

7) Read the codes from the flashing LED on the side of the ECU or the check engine light itself. Long flash is first digit, short flash is 2nd digit, the codes are at the bottom of this page.

8) To exit MODE II Diagnostics, turn potentiometer fully clock-wise. Wait at 2-3 seconds, then turn the potentiometer fully counter clock-wise.


To enter Mode II - Heated Oxygen (O2) Sensor Monitor:

1) Start engine with the ECU in MODE II . The ECU is now monitoring the left O2 sensor. Warm the engine to normal operating temperature, then run at 2000 rpm for 2 minutes. Check that the LED blinks (or the check engine light) more than 5 times every 10 seconds at 2000 rpm.

2) To change to right sensor turn the ECU potentiometer clockwise with engine still running, wait 2 seconds, turn it back. Check the lights at 2000 rpm again for a similar switching condition.

3) To exit MODE II - Heated Oxygen Sensor Monitor, turn the potentiometer fully counter clock-wise and stop the engine.

*Light indicates signal from sensor to ECU. ON = RICH while Off = LEAN. Blinking light means system is constantly adjusting between lean and rich which is normal. Any other indication would be abnormal and require further troubleshooting. The switched on/off is 'closed loop', while a constant on or off is 'open loop'


ECU Diagnostics Codes:

11: crank angle sensor circuit
12: Air Flow Meter Circuit
13: Engine Coolant Temp Sensor Circuit
14: Speed Sensor Circuit
21: Ignition Signal Circuit
26: Boost Pressure Sensor (TT Only)
31: ECU
32: EGR Function
33: Exhaust Gas Sensor Circuit (left)
34: Detonation Sensor Circuit
35: Exhaust Gas Temp Sensor Circuit
42: Fuel Temp Sensor Circuit
43: Throttle Position Sensor Circuit
45: Injector Leak
51: Injector Circuit
53: Exhaust Gas Sensor Circuit (right)
54: Signal Circuit from A/T Control to ECU (Automatic Only)
55: No fault found, everything is hunky dory!


Here's what to make of all the codes above:

ECU Code Code Description Probable Cause
Code 11

Camshaft Angle Sensor circuit (CAS)

Either 1 or 120 signal is not entered for the first few seconds of engine cranking.
Either 1 or 120 signal is not input often enough while the engine speed is higher then the specified RPM.
Harness and connector (if harness and connector are OK, CAS might be bad)
Code 12

Mass Air-Flow Sensor circuit (MAS)

The MAS sensor circuit is open or shorted (abnormally high or low voltage is registered). Harness and connector (if harness and connector are OK, MAS might be bad)
Code 13

Engine Coolant Temp. Sensor

The Engine Coolant Temp. Sensor circuit is open or shorted (abnormally high or low voltage is registered). Harness and connector
Engine Coolant Temp. Sensor
Code 14

Speed Sensor circuit

The Speed Sensor circuit is open or shorted. Harness and connector
Speed Sensor switch (reed switch)
Code 21

Ignition signal circuit

The ignition signal in the primary circuit is not entered during engine cranking or running. Harness and connector
Power Transistor Unit
Code 26 (Twin Turbo Only)

Boost Pressure sensor

The boost pressure sensor is open or shorted (abnormally high or low voltage is registered). Harness and connector
Boost pressure leaks
Boost pressure sensor
Code 31

ECU

ECU calculation function is failing Repair or replace ECU
32 EGR function EGR valve does not operate (valve spring does not lift) EGR valve
EGRC-solenoid valve
Code 33

O2 Sensor (left side)

The O2 Sensor is open or shorted (abnormally high or low voltage is registered). Harness and connector
O2 sensor
Fuel pressure
Injectors
Intake air leaks
Code 34

Detonation Sensor circuit

The detonation sensor circuit is open or shorted (abnormally high or low voltage is registered). Harness and connector
Detonation sensor
Code 35

EGR Temp. Sensor

The EGR Temp. Sensor circuit is open or shorted (abnormally high or low voltage is registered). Harness and connector
EGR temp. sensor
Code 42

Fuel Temp Sensor circuit

The Fuel Temp. Sensor circuit is open or shorted (abnormally high or low voltage is registered). Harness and connector
Fuel temp. sensor
Code 43

Throttle Position Sensor circuit

The Throttle Position Sensor circuit is open or shorted (abnormally high or low voltage is registered). Harness and connector
Throttle position sensor
Code 45

Injector leak

Fuel leaks from the injectors Injectors
Code 51

Injector circuit

The injector circuit is open Harness and connector
Injectors
Code 53

O2 Sensor (right side)

The O2 Sensor is open or shorted (abnormally high or low voltage is registered). Harness and connector
O2 sensor
Fuel pressure
Injectors
Intake air leaks
Code 54

Signal circuit from the automatic transmission (A/T models only)

The A/T communication line is open or shorted Harness and connector

Zmods.org screen name: Twisted Six
3ZC screen name: Twisted Six
AIM screen name: TT2by2

» You are NOT logged in!
You made it to the bottom of the page, and still aren't logged in!! If you haven't registered yet, please do so by clicking  here. The benefits of registering include an endless wealth of  technical information, access to our forums, and best of all, this god awful big red eye sore of a notice will disappear!! I'm sure you're tired of looking at this gaudy notice by now!


Zmods.org | Z32 Restoration & Tech 2003 - 2017
Powered by: vBulletin Version 3.0.11
Copyright ©2000 - 2017, Jelsoft Enterprises Ltd.
All times are GMT -4. The time now is 09:15 AM.