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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 |
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